(12) Patent Application Publication (10) Pub. No.: US 2003/0003300 A1 Korgel Et Al

US 20030003300A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2003/0003300 A1 KOrgel et al. (43) Pub. Date: Jan. 2, 2003

(54) LIGHT-EMITTING NANOPARTICLES AND Publication Classification METHOD OF MAKING SAME (51) Int. Cl." ...... B32B 1700; CO9K11/00; (76) Inventors: Brian A. Korgel, Round Rock, TX HO5B 33/14 (US); Keith P. Johnston, Austin, TX (52) U.S. Cl...... 428/402; 428/403; 428/690; (US) 428/917; 427/215; 313/503; 257/88 Correspondence Address: ERC B. MEYERTONS (57) ABSTRACT CONLEY, ROSE & TAYON, PC. P.O. BOX 398 AUSTIN, TX 78767-0398 (US) A method for the production of a robust, chemically stable, crystalline, passivated nanoparticle and composition con (21) Appl. No.: 10/109,578 taining the same, that emit light with high efficiencies and size-tunable and excitation energy tunable color. The meth (22) Filed: Mar. 28, 2002 ods include the thermal degradation of a precursor molecule Related U.S. Application Data in the presence of a capping agent at high temperature and elevated pressure. A particular composition prepared by the (60) Provisional application No. 60/302,594, filed on Jul. methods is a passivated Silicon nanoparticle composition 2, 2001. displaying discrete optical transitions. Patent Application Publication Jan. 2, 2003 Sheet 1 of 31 US 2003/0003300 A1

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LIGHT-EMITTING NANOPARTICLES AND electronic transitions in the absorbance and photolumines METHOD OF MAKING SAME cence excitation (PLE) spectra. 0009. The wet chemical techniques used to synthesize PRIORITY CLAIM Group II-VI and III-V semiconductors have not been readily 0001. This application claims priority to Provisional applied to Group IV materials, largely due to the high Patent Application No. 60/302,594 entitled “Light-Emitting temperatures required to degrade the necessary precursors. Nanocrystals' filed on Jul. 2, 2001. Typically the temperature required to degrade the necessary Group IV precursors exceeds the boiling points of typical STATEMENT REGARDING FEDERALLY Solvents. Furthermore, the Strong covalent bonding of Si SPONSORED RESEARCH requires temperatures higher than the Group II-VI materials to achieve highly crystalline cores. Moderate progreSS has 0002 The United States Government has rights in this been made with alternative solution-phase reduction of Si invention pursuant to National Science Foundation Contract Salts and aerosol methods. These methods, however, have No. 26-1122-2OXX. produced nanocrystals with extremely broad size distribu tions. AeroSol methods have required a thick oxide coating BACKGROUND OF THE INVENTION to stabilize their structure, which has been shown recently to Significantly affect the photoluminescence (PL) energies of 0003) 1. Field of the Invention porous Si. 0004. The present invention relates to the field of nano technology. In particular, to compositions and methods of SUMMARY OF THE INVENTION making Group IV metal nanoparticles and their applications. 0010. In an embodiment Group IV metals form nanoc 0005 2. Description of the Relevant Art rystalline or amorphous particles by the thermal degradation 0006 The term “nanoparticle' generally refers to par of a precursor molecule in the presence of molecules that ticles that have an average diameter between about 1 nm to bind to the particle Surface, referred to as a capping agent at 100 nm. Nanoparticles have an intermediate size between high temperature and elevated pressure. In certain embodi individual atoms and macroscopic bulk Solids. Nanopar ments, the reaction may run under an inert atmosphere. In ticles typically have a size on the order of the Bohr exciton certain embodiments the reaction may be run at ambient radius, or the de Broglie wavelength, of the material, which preSSures. The particles may be robust, chemically stable, allows individual nanoparticles to trap individual or discrete crystalline, or amorphous and organic-monolayer passi numbers of charge carriers, either electrons or holes, or Vated, or chemically coated by a mixture of organic mol excitons, within the particle. The Spatial confinement of ecules. In one embodiment, the particles emit light in the electrons (or holes) by nanoparticles is believed to alter the ultraViolet wavelengths. In another embodiment, the par physical, optical, electronic, catalytic, optoelectronic and ticles emit light in the visible wavelengths. In other emo magnetic properties of the material. The alteration of the bodiments, the particles emit light in the near-infrared and physical properties of a nanoparticle due to confinement of the infrared wavelengths. The particles may emit light with electrons is generally referred to as quantum confinement high efficiencies. Color of the light emitted by the particles effects. may be size-tunable and excitation energy tunable. The light emission may be tuned by particle size, with Smaller par 0007 Nanoparticles may exhibit a number of unique ticles emitting higher energy than larger particles. The electronic, magnetic, catalytic, physical, optoelectronic and Surface chemistry may also be modified to tune the optical optical properties due to quantum confinement effects. For properties of the particles. In one embodiment, the Surfaces example, many nanoparticles exhibit photoluminescence may be well-passivated for light emission at higher energies effects that are Significantly greater than the photolumines than particles with Surfaces that are not well-passivated. The cence effects of macroscopic molecules having the same average diameter of the particles may be between 1 and 10 composition. Additionally, these quantum confinement nm. A particular composition prepared by the methods is a effects may vary as the size of the nanoparticle is varied. For passivated Silicon nanoparticle composition displaying dis example, size-dependent discrete optical and electronic tran crete optical transitions and photoluminescence. sitions exist for clusters of Group II-VI semiconductors (e.g., CdSe) or Group III-V semiconductors (e.g., InAs). 0011. In an embodiment, a solvent may be used to assist in Solvating the precursors and capping agents. The Solvent 0008. This loss of energy level degeneracy, however, has not previously been observed in the optical properties of may be Substance capable of dissolving the precursor and Group IV nanoparticles (e.g., Silicon (Si) nanocrystals). In capping agents. The capping agent may act as the Solvent. Si, for example, the lowest lying energetic transition violates 0012. In certain embodiments, the nanoparticles may conservation of momentum; therefore, light absorption include capping agents. The capping agents may include an requires phonon assistance (a phonon is a quanta of vibra end bound to the Surface of the particle. Capping agents may tional energy), resulting in a very low transition probability. assist in protecting the particle from oxidation and/or water. Consequently, bulk Si photoluminescence is very weak. Capping agents may assist in Solubilizing, or dispersing, the Quantum confinement in Si nanocrystals and porous Si, particles. In one embodiment, polar capping agents might be however, leads to enhanced luminescence efficiencies with used to disperse particles in aqueous media. In another quantum yields that have reached as high as 5% at room embodiment, organic, largely hydrocarbon, capping agents temperature and blue-shifted “band gap' energies. However, might be used to disperse particles in organic Solvents. In in Sharp contrast to their direct band gap Semiconductor another embodiment, a mixture of polar and organic capping counterparts, Si nanocrystals have not displayed discrete agents may be used to disperse the particles in a polar US 2003/0003300 A1 Jan. 2, 2003

organic Solvent. In another embodiment, fluorinated capping 0022. In some embodiments, a nanoparticle may be agents may be used to disperse the particles in carbon formed by a method comprising heating a mixture of one or dioxide, or other fluorocarbon Solvents. Capping agents may more organometallic precursors and a capping agent in a assist in controlling the formation of the particles during the Supercritical fluid. The method may include decomposing reaction, by decreasing aggregation of the particles as the the organometallic precursors, forming the nanoparticles. particles form. 0023. In an embodiment, a nanoparticle may include a 0013 In some embodiments, a flow through processor metal and a capping agent coupled to the metal. The may be used to form the nanoparticles. The processor may nanoparticle may have an average particle diameter of allow for the continuous production of particles on a large between about 1 to about 100 angstroms. The capping agent Scale. may inhibit oxidation of the nanoparticle. 0.014. In certain embodiments, the nanoparticles formed 0024 Certain embodiments may include a method of by the method described herein may be used in a variety of forming nanoparticles including heating a mixture of one or applications. Several examples of possible applications are more metal Salts and a capping agent in Supercritical water. described herein and include: lights, light emitting diodes, The metal Salts may decompose, forming the nanoparticles. flat panel displayS, biological assays, biological Sensors, 0025. In other embodiments, a nanoparticle may be memory devices, and transistors. The methods described formed by the method comprising heating a mixture of one herein may create Group IV particles with novel properties. or more metal Salts and a capping agent in Supercritical 0.015. In an embodiment, a method of forming nanopar water. The metal Salts may decompose, forming the nano ticles may include heating a mixture of a Group IV metal particles. organometallic precursor and a capping agent at a tempera 0026. In an embodiment, a nanoparticle may include a ture where the precursor decomposes forming the nanopar metal oxide and a capping agent coupled to the metal oxide. ticles. The nanoparticle may have an average particle diameter of 0016. In some embodiments, it should be understood that between about 1 to about 100 angstroms. The capping agent heating the mixture in order to decompose the precursors to may inhibit oxidation of the nanoparticle. form nanoparticles may include heating at a temperature at 0027. An embodiment of a method of forming nanopar or below the Supercritical temperature of the capping agent ticles in a continuous manner may include injecting a or a Solvent (in embodiments where the capping agent does mixture of an organometallic precursor and a capping agent not act as the Solvent). into a reactor. The method may include heating the mixture 0.017. In certain embodiments, it should be understood within the reactor to a temperature wherein the precursor that heating the mixture in order to decompose the precur decomposes forming the nanoparticles. In addition the Sors to form nanoparticles may include heating at a tem method may include removing the formed nanoparticles perature above about 300° C. and below the Supercritical from the reactor while Substantially Simultaneously injecting temperature of the capping agent or a Solvent (in embodi additional organometallic precursors and capping agents ments where the capping agent does not act as the Solvent). into the reactor. 0028. In certain embodiments, a nanoparticle may be 0.018. In other embodiments, it should be understood that formed by a method including heating a mixture of one or heating the mixture in order to decompose the precursors to more organometallic precursors and a capping agent in a form nanoparticles may include heating at a temperature fluid at a temperature above about 300° C. and below the below the Supercritical temperature of the capping agent or Supercritical temperature of the fluid. a Solvent (in embodiments where the capping agent does not act as the Solvent). The temperature may be not less than 0029. In other embodiements, a nanoparticle may be about 100° C. below the Supercritical temperature of the formed by a method comprising heating a mixture of one or fluid capping agent or a Solvent (in embodiments where the more organometallic precursors and a capping agent in a capping agent does not act as the Solvent). fluid at a temperature below the Supercritical temperature of the fluid. The temperature of the fluid may be not less than 0019. In an embodiment, a nanoparticle may be formed about 100° C. below the Supercritical temperature of the by a method including heating a mixture of a Group IV fluid. organometallic precursor and a capping agent. Heating the mixture may include heating the mixture at a temperature 0030. An embodiment of a light emitting device may where the precursor decomposes forming the nanoparticle. include a plurality of nanoparticles. The nanoparticles may include a Group IV metal and a capping agent coupled to the 0020 Certain embodiments may include a nanoparticle Group IV metal. The nanoparticles may have an average including a Group IV metal and a capping agent coupled to particle diameter of between about 1 to about 100 ang the Group IV metal. The nanoparticle may have an average Stroms. The light emitting device may include an anode particle diameter of between about 1 to about 100 ang electrically coupled to the plurality of nanoparticles. The Stroms. The capping agent may inhibit oxidation of the light emitting device may include a cathode electrically nanoparticle. coupled to the plurality of nanoparticles. The anode and the 0021. An embodiment may include a method of forming cathode together may be configured to conduct an applied nanoparticles including heating a mixture of one or more current to the nanoparticles. The nanoparticles may produce organometallic precursors and a capping agent in a Super light in response to the applied current. critical fluid. The method may include decomposing the 0031. An embodiment of a light emitting device may organometallic precursors, forming the nanoparticles. include a plurality of nanoparticles. The nanoparticles may US 2003/0003300 A1 Jan. 2, 2003 be formed by a method including heating a mixture of a a temperature wherein the precursor decomposes, and the Group IV organometallic precursor and a capping agent at a nanoparticle is formed. The nanoparticles may include a temperature. Heating the mixture may decompose the pre metal and a capping agent coupled to the metal. At least one cursor forming the nanoparticles. The light emitting device of the nanoparticles may have an average particle diameter may include an anode electrically coupled to the plurality of of between about 1 to about 100 angstroms. The coherent nanoparticles. The light emitting device may include a light emitting device may include an excitation Source cathode electrically coupled to the plurality of nanoparticles. functioning to apply energy to the nanoparticles in an The anode and the cathode together may be configured to absorbable form. The coherent light emitting device may conduct an applied current to the nanoparticles. The nano include an optical cavity functioning to direct light. When particles may produce light in response to the applied the excitation Source applies energy to nanoparticles the Current. nanoparticles may produce light. Light produced by the 0032) Certain embodiments of a display apparatus may nanoparticles may be directed by the optical cavity. include a Support and a plurality of light emitting devices 0037. In an embodiment, a system for at least partially positioned on the Support. The light emitting devices may containing an electrical charge temporarily may include a include a plurality of nanoparticles. The nanoparticles may cathode comprising a plurality of nanoparticles. The nano include a Group IV metal and a capping agent coupled to the particle may be formed by a method including heating a Group IV metal. The nanoparticle may have an average mixture of a Group IV organometallic precursor and a particle diameter of between about 1 to about 100 ang capping agent at a temperature wherein the precursor Stroms. The light emitting devices may include a conductive decomposes, and the nanoparticle is formed. The nanopar material electrically coupled to the plurality of nanopar ticles may include a metal and a capping agent coupled to ticles. The conductive material may function to conduct an the metal. The metal may be a Group IV metal. At least one applied current to the particles. The display apparatus may of the nanoparticles may have an average particle diameter include a controller functioning to control the application of of between about 1 to about 100 angstroms. The nanopar current to each of the lights. ticles may be electroactive. The System may include an 0033. An embodiment of a system for detecting an ana anode. The anode may include an electroactive material. The lyte in a fluid may include a nanoparticle. The nanoparticle System may include a separator positioned between the may include a Group IV metal and a capping agent coupled cathode and the anode functioning to inhibit contact between to the Group IV metal. The metal nanoparticle may have an a portion of the cathode and a portion of the anode. average particle diameter of between about 1 to about 100 0038. In an embodiment, a system for electrically com angstroms. The System may include a receptor which func municating with a biological entity may include a nanopar tions to interact with the analyte. The receptor may be ticle. The nanoparticle may be formed by a method includ coupled to the nanoparticle. ing heating a mixture of a Group IV organometallic 0034. An embodiment of a system for detecting an ana precursor and a capping agent at a temperature wherein the lyte in a fluid may include a nanoparticle. The nanoparticle precursor decomposes, and the nanoparticle is formed. The may be formed by a method comprising heating a mixture of nanoparticle may include a metal and a capping agent a Group IV organometallic precursor and a capping agent. coupled to the metal. The metal may be a Group IV metal. Heating the mixture may include heating the mixture at a At least one of the nanoparticles may have an average temperature where the precursor decomposes forming the particle diameter of between about 1 to about 100 ang nanoparticle. The System may include a receptor which Stroms. At least one of the nanoparticles may produce an functions to interact with the analyte. The receptor may be electric field in response to a Stimulus. The System may coupled to the nanoparticle. include a receptor functioning to interact with the biological entity. The receptor may be coupled to the nanoparticle. 0.035 An embodiment of a memory device which may include a Source functioning to apply an electrical charge. BRIEF DESCRIPTION OF THE DRAWINGS The memory device may include a drain functioning to hold an electric charge. The memory device may include a 0039. The above brief description as well as further channel functioning to Separate the Source and the drain. The objects, features and advantages of the methods and appa memory device may include a floating gate positioned above ratus of the present invention will be more fully appreciated the channel. The floating gate may include a plurality of by reference to the following detailed description of pres nanoparticles. Where at least a plurality of the nanoparticles ently preferred but nonetheless illustrative embodiments in may include a Group IV metal and a capping agent coupled accordance with the present invention when taken in con to the Group IV metal. At least one of the nanoparticles may junction with the accompanying drawings. have an average particle diameter of between about 1 to about 100 angStroms. The memory device may include a 0040 FIG. 1 depicts a schematic flow chart of an control gate positioned Substantially adjacent the floating embodiment of a batch reaction method. gate. The memory device may include and a conductor 0041 FIG. 2 depicts an embodiment of the invention comprising an oxide positioned between the control gate and showing a sterically Stabilized nanoparticle with attached the floating gate. The floating gate may be positioned capping ligands. between the channel and the control gate. 0036). In an embodiment, a coherent light emitting device 0042 FIG. 3 depicts a schematic of an embodiment of a may include a plurality of nanoparticles. The nanoparticle continuous flow production System. may be formed by a method including heating a mixture of 0043 FIG. 4 depicts an embodiment of a floating gate a Group IV organometallic precursor and a capping agent at memory device. US 2003/0003300 A1 Jan. 2, 2003

0044 FIG. 5 depicts an embodiment of a basic design for 0065 FIG. 26 depicts an example of blinking-a compari a light emitting device. Son between the blinking of a single dot (top) and the 004.5 FIG. 6 depicts an embodiment of a basic design for blinking of a cluster (bottom); inset shows a histogram of the a flat panel display. “off” times for the single dot blinking. 0066 FIG. 27 depicts an example of an average room 0.046 FIG. 7 depicts an embodiment of a basic design for a flat panel display including multiple layers of transparent temperature lifetime measurement of the ensemble. light emitting devices. 0067 FIG. 28 depicts an example of an observation of “molecular” (-) and “continuum' (-) like Single nanoc 0047 FIG. 8 depicts a schematic representation of an rystal spectra. Average of 37 molecular type spectra and 31 embodiment of a nanoparticle labeled analyte. continuum type spectra from Single nanoparticles excited at 0.048 FIG. 9 depicts an embodiment of a basic design for 488 nm. Each spectra was shifted So that its maximum was a laser with an optical excitation Source. at Zero before averaging. Histogram insets of Spectral maxima (émax) of continuum type and molecular type 0049 FIG. 10 depicts an embodiment of a basic design Spectra, respectively. for a laser using an electrical excitation Source. 0068 FIG. 29 depicts an example of a comparison of the 0050 FIG. 11 depicts a schematic of an embodiment of measured ensemble spectra (-) to the reconstructed a battery based on the nanoparticles described herein. ensemble spectra. reconstructed from the Single dot Spectra 0051 FIG. 12 depicts an example of energy-dispersive (-) of 68 individual Silicon nanoparticles. X-ray SpectroScopy analysis of an exemplary nanoparticle 0069 FIG. 30 depicts a table of fluorescence lifetime composition. measurements on Si nanoparticle dispersions. The fluores 0.052 FIG. 13 depicts an example of X-ray Photoelectron cence decay curves were fit with three exponential functions. Spectroscopy analysis of an exemplary nanoparticle compo 0070 FIG. 31 depicts a schematic of an experimental Sition. Setup for electrochemistry and electrogenerated chemilumi 0053 FIG. 14 depicts an example of Fourier transformed neScence of nanoparticles. infrared spectroScopy analysis of an exemplary nanoparticle 0071 FIG. 32 depicts several examples of cyclic volta composition. mmograms and differential pulse Voltammograms for Sev 0054 FIG. 15 depicts an example of photoluminescence eral batches of Silicon nanoparticles. (PL) and photoluminescence excitation (PLE) spectral 0072 FIG. 33 depicts several examples of electrogener analysis of exemplary nanoparticle compositions. ated chemiluminescence transients. 0055 FIG. 16 depicts an example of an absorbance 0073 FIG. 34 depicts several examples of electrogener profile of exemplary nanoparticle compositions. ated chemiluminescence spectra. 0056 FIG. 17 depicts a comparison between the extinc 0074 FIG. 35 depicts a schematic of an embodiment of tion coefficients of bulk Silicon as compared to the extinction a mechanism for electrogenerated chemiluminescence and coefficient of an exemplary nanoparticle composition. photoluminescence of Silicon clusters and an example of a 0057 FIG. 18 depicts an example of room temperature photoluminescence spectra at different excitation energy. photoluminescence (PL) and photoluminescence excitation (PLE) spectra of CdS qdots. DETAILED DESCRIPTION 0.058 FIG. 19 depicts an example of room temperature 0075 Nanoparticles may be prepared by using the meth ods described herein. In one embodiment, nanoparticles may absorbance spectrum of an aqueous dispersion of CdS be formed by reacting an organometallic precursor in the quantum dots. presence of a capping agent. The organometallic precursor 0059 FIG. 20 depicts an example of room temperature and capping agent may be heated at a pressure greater than absorbance spectra of CdS qdots and CdS/antibody com 1 atm. in a reaction vessel. The reaction vessel may be made plexes. of type II titanium, or other titanium, StainleSS Steel, or any other material rated for high temperatures and high pres 0060) FIG. 21 depicts examples of single dot PL spectra. Sures. Heating of the organometallic precursor results in the 0061 FIG. 22 depicts examples of X-ray Photoelectron thermal degradation of the organometallic precursor, which spectroscopy (XPS) of uncapped and capped copper nano in turn leads to the formation of nanoparticles. The precursor particles. may degrade through a free radical mechanism, or it may degrade through thermolysis. The dimensions of the nano 0.062 FIG. 23 depicts an example of room-temperature particles may be controlled by reaction conditions and the UV-Visible spectra of organically capped copper nanopar capping agent used. The reaction conditions used to control ticles. the particle size may include, for example, the temperature, 0.063 FIG. 24 depicts an example of an atomic force preSSure, precursor concentration, capping ligand concen microscopy (AFM) histogram showing a Silicon nanopar tration, Solvent, precursor composition and capping agent composition. In one embodiment a free radical initiator may ticle height distribution. be added to the reaction. The nanoparticle may be controlled 0.064 FIG. 25 depicts an example of room temperature Structure with a capping ligand or passivating ligand. It is absorbance, PLE and PL spectra for silicon nanoparticles. believed that the capping agent may aid in controlling the US 2003/0003300 A1 Jan. 2, 2003

dimensions of the formed nanoparticles by inhibiting growth atoms. X may be an atom that includes, but is not limited to, of the nanoparticles. The capping agent may also prevent nitrogen, carbon, oxygen, Sulfur, and phosphorus. Alterna reactive degradation of the nanoparticles when exposed to tively, X may be a functional groups that includes, but is not water and oxygen and other chemical contamination. limited to, a carboxylate, a Sulfonate, an amide, an alkene, an amine, an alcohol, a hydroxyl, a thioether, a phosphate, 0.076 Under the reaction conditions of high temperature an alkyne, an ether, or a quaternary ammonium group. and pressure, the Size of nanoparticles may be controlled by Examples of capping agents include, but are not limited to, altering the pressure, temperature, amount of precursor, alcohols, alkenes, alkynes, thiols, ethers, thioethers, phos amount of capping agent or by altering a combination of phines, amines, amides, carboxylates, Sulfonates, or quater conditions and reagents to produce a narrow distribution of nary ammonium compounds. nanoparticle Size ranges. In Some embodiments, conditions may be controlled for the express purpose of producing a 0080. In some embodiments, the capping agent may be wide distribution of nanoparticle Size ranges. It should be an alcohol. Alcohols that may be used include n-alcohols appreciated that the methods and compositions described having between 1 to 20 carbon atoms. An example of Such can be modified to accommodate the construction of nano an n-alcohol is 1-octanol. In other embodiments, the capping particles from a variety of thermally degradable precursors agent may be an alkene. Alkenes that may be used include by modifying the reaction vessel, addition of a Solvent, alpha-olefins having between 1 to 20 carbon atoms, or altering the capping agent, and/or reagents, or through the olefins with unsaturated chains. An example of Such an Sequential addition of reactants after initial particle nucle alkene is 1-octene. In another embodiment the capping agent ation. may be a thiol. Thiols that may be used include 1-thiols having between 1 to 20 carbon atoms. An example of Such 0077. The organometallic precursor may be a Group IV a thiol is 1-thiooctanol. metal that includes organic groups. AS used herein a “Group IV metal' includes the elements of Silicon, germanium, and 0081. The reaction of the organometallic precursor and tin. Generally, organometallic Group IV precursors are com the capping agents is conducted at temperature above room pounds that may be thermally degraded to form nanopar temperature (e.g., above about 25 C.), and at pressures ticles that are composed primarily of the Group IV metal. In above atmospheric pressure (e.g., above about 1 atm.). The Some embodiments, the nanoparticle contains a mixture of temperature chosen for the reaction is Such that the organo Group IV elements, Such as SiGe , Si,Snor GeSn metallic precursor will be thermally decomposed to produce x. Organometallic Group IV precursors include, but are not the nanoparticles. In Some embodiments, a reducing agent, limited to organosilicon, organogermanium and organotin such as sodium borohydride, or lithium borohydride, or compounds. Some examples of Group IV precursors hydrogen, might be added to aid nanoparticle formation. In include, but are not limited to, alkylgermaniums, alkylsi Some embodiments, the reaction may be conducted in a lanes, alkylstannanes, chlorosilanes, chlorogermaniums, preSSurized reaction vessel at a temperature above the boil chloroStannanes, aromaticsilanes, and aromatic germaniums ing point of the organometallic precursor, the capping agent, and aromaticStannanes. Particular examples of organome or both the organometallic precursor and the capping agent. tallic Silicon precursors include, but are not limited to, Thus, a reaction may be at a temperature above the boiling tetraethyl Silane or diphenylsilane. Particular examples of point of one or more of the reactants and be pressurized Such organometallic germanium precursors include, but are not that the solvent is kept in a liquid or diffusible state. The limited to, tetraethylgermane or diphenylgermane. reaction mixture may be heated and pressurized above the critical point of the mixture, or it may be below the critical 0078. The capping agent may interact with an organo point of the mixture, either as a Superheated liquid, or in the metallic precursor during formation of the nanoparticle to gas-liquid two-phase region of the phase diagram. The assist in controlling the growth of the particle. The capping preSSure under which a reaction is performed may be high agent may bond covalently to the particle Surface, or Stick enough to raise the boiling point of a Solvent but Still be through weak interactions, Such as hydrogen bonding. The below the critical preSSure of a Solvent. The temperature and capping agents may physisorb to the particle Surface. In one preSSure may be Such that the precursor and capping ligands embodiment, capping of the particle Surfaces may occur will be diffusible in the Solvent. through a combination of organic ligands and inorganic Small molecules. Oxygen or Sulfur may also bond to the 0082 In other embodiments, the reaction may be con Surface in Some instances. Additionally, the capping agent ducted in a Super critical fluid. A Supercritical fluid is may assist in Solubilizing the organomettalic precursor. obtained by heating a fluid above the critical temperature Additionally, two or more kinds of capping agents might be and at a preSSure above the critical pressure for the fluid. The added to the reaction mixture. In one embodiment, a mixture critical temperature and critical pressure for a fluid is known of organometallic precursors may be added to the reactor for as the critical point. Above the critical point neither a liquid particle formation. nor gas State exist. Instead a phase known as a Supercritical fluid exists. For example, a gas enters the Supercritical State 0079 Capping agents include compounds having the when the combination of preSSure and temperature of the general formula (R)-X, where X is an atom or functional environment in which the gas is contained is above a critical group capable of binding to the Surface of the nanoparticles. state. The critical temperature of octanol is 385 C. The The term “binding” refers to an interaction that associates critical pressure of octanol is 34.5 bar. When octanol is the capping agent with the nanoparticles. Such interactions subjected to temperatures and pressures above 385 C. and may include ionic, covalent, dipolar, dative, quadrupolar or 34.5 bar, the octanol exists in a Supercritical State. The Van der Walls interactions. Each R group is independently critical temperature and preSSure of other components may hydrogen, an aryl group having between 1 and 20 carbon be readily calculated or experimentally determined. The atoms or an alkyl group having between 1 and 20 carbon particle size may be controlled by varying the pressure of the US 2003/0003300 A1 Jan. 2, 2003

reaction mixture under isothermal conditions above or preSSure of a Solvent. The temperature and pressure may be below the critical point of the mixture. The particle size may Such that the precursor and capping ligands will be diffusible be controlled by varying the temperature of the reaction in the Solvent. mixture under isobaric reaction conditions above or below 0087. In other embodiments the solvent may be at Super the critical point of the mixture. critical conditions. The temperature and pressure may be 0.083. A compound or element above the critical tempera Such that the precursor and capping agents will be diffusible ture and critical pressure is referred to as a Supercritical in the Solvent. Thus, reaction condition may be above and fluid. Supercritical fluids may have high Solvating capabili below the critical point of a solvent. ties that are typically associated with compositions in the 0088. The temperatures at which the reactions are carried liquid State. Supercritical fluids also have a low Viscosity out are Sufficient for the thermal degradation of the precursor that is characteristic of compositions in the gaseous State. molecules. The temperature of the reaction will vary with Additionally, a Supercritical fluid maintains a liquids ability the characteristics of the precursor molecules. In certain to dissolve Substances. embodiments the temperature may be in the approximate 0084. Many organometallic Group IV metal precursors range of 300° C. to 800° C., in some embodiments 400° C. require high temperatures (above about 300° C.) to induce to 700° C. and the temperature can be approximately 450 the decomposition into nanoparticles. The high temperatures C. to 550° C. In an embodiment the reaction may be needed to decompose the organometallic precursors typi approximately 500 C. cally exceed the boiling points of the capping agent, the 0089. The pressure at which the reaction is carried out Solvent, and the precursor itself. The use of elevated pressure should be Sufficient to maintain at least a portion of the or Super critical conditions allows the decomposition of precursor and at least a portion of the capping ligand in a organometallic precursors to form nanoparticles using the diffusible State and/or a Solvent in a dense liquid or gaseous capping agents described above. In one embodiment, the State with a Solvent density above 0.1 g/mL. In certain high temperatures are necessary to drive the reaction embodiments the reaction conditions may be beyond the between the nanoparticle Surface and the capping agents. In critical point of a Solvent and/or capping agent. For example, another embodiment, the capping agent may react Sponta it is envisioned that Supercritical octanol can be used as a neously upon nanoparticle formation. capping agent. In certain embodiments preSSures of approxi 0085. In some embodiments, the reaction may be con mately 2 to 500 bar may be used. In other embodiments the ducted at a temperature and pressure that is above the critical approximate range of pressure may be 25 to 400 bar. In point of the capping agent. The capping agent may, there certain embodiments approximately 50-350 bar is preferred. fore, become a Supercritical fluid. This allows the reaction to 0090 When a solvent is used the organometallic precur be conducted at a temperature that induces decomposition of Sor may be present in the initial reaction Solution at various the organometallic precursor and reaction of the capping concentrations ranging from nanomolar to micromolar to agent with the forming nanoparticle. Additionally, the Super molar concentrations. In certain embodiments a precursor critical fluid may promote rapid reactant diffusion. Rapid may be present in the approximate range of 10 mM to 5 M, diffusion of the reactants may allow diffusion-limited 125 to 625 mM, 250 to 500 mM, 300 to 500 mM, or 400 mM growth which may lead to narrow particle size distributions. to 1 M. Additionally, the mole ratio of capping agent to the Particles may also grow through a coagulative growth organometallic precursor may be in the approximate range process to yield Stable redispersible nanoparticles. of 1,000,000:1 to 1:1,000 when a solvent is used. In other embodiments the ratio may be in the approximate range of 0.086. In another embodiment, the decomposition of the 10,000:1 to 1:10,000. In other embodiments the mole ratio organometallic precursor may be conducted in the presence of reagents may be in an approximate range from 1 to of a capping agent and a Substantially inert Solvent. Gener 1,000,000 parts capping agent to 1 to 10 parts precursor ally, a Solvent will dissolve both precursor molecules and capping agents. Examples of Solvents that may be used molecule, or in the approximate range of 500 to 50,000 parts include, but are not limited to, hydrocarbons, alcohols, capping agent to 1 to 10 parts precursor molecule, or in the ketones, ethers and polar aprotic Solvents (e.g., dimethyl approximate range of 800 to 10,000 parts capping agent to formamide, dimethylsulfoxide, etc). Hydrocarbon solvents 1 to 10 parts precursor molecule. include, but are not limited to aromatic and non-aromatic 0091 Nanoparticles may be produced using a batch pro hydrocarbon carbons. Examples of aromatic hydrocarbon ceSS, a Semibatch proceSS or a continuous flow process. FIG. Solvents include, but are not limited to benzene, toluene, and 1 illustrates an embodiment of an apparatus for producing Xylenes. Examples of non-aromatic hydrocarbon Solvents nanoparticles using a batch process. Reaction vessel 2 may include cyclic hydrocarbons (e.g., cyclohexane, cyclopen be in fluid communication with high-pressure pump 4. tane, etc.) and aliphatic hydrocarbons (e.g., hexane, heptane, Reaction vessel 2 may be a stainless steel cell (High Pressure octane, etc.). In certain embodiments the reaction may be Equip. Co., Buffalo, N.Y.), or an inconnel high pressure cell, performed at conditions, Such as temperature and pressure, or a titanium cell. Alternative high-pressure vessels may be which are below the critical point of solvent, but above the used to carry out the methods of the invention. Alternatives boiling point of the Solvent. Thus, a reaction may be at a include, but are not limited to, iron based alloys and titanium temperature above its ambient boiling point and be preSSur alloys. Reaction vessel 2 may be operatively coupled to ized such that the boiling point is elevated above the thermal Source 6 and thermometer 8. Reagents are pumped temperature of the reaction conditions, thus maintaining the into reaction vessel 2 from a reagent reservoir 10. Reagent solvent in a liquid or diffusible state. The pressure under reservoir 10 may include the Solvent, precursor, and capping which a reaction is performed may be high enough to raise agent. Once the reagents are pumped into reaction vessel 2 the boiling point of a solvent but still be below the critical reaction vessel 2 may be pressurized and heated to the US 2003/0003300 A1 Jan. 2, 2003 appropriate temperature and pressure. After allowing Suffi ticles in the 25-40 nm range. In this example, nanoparticles cient time for the thermal degradation of a precursor mol having an average particle size greater than 40 nm or leSS ecule and the Subsequent formation of nanoparticles the than 25 nm do not aggregate and remain dispersed in the reaction may be cooled and brought to ambient pressures. Solvents. The aggregated particles may be removed by The reaction may occur in a matter of Seconds, or in Some filtration. By varying the solvent used, the size of the embodiments, the reaction occurs in a matter of Several nanoparticles that aggregate may be altered allowing easy hours. The reaction time, or the residence time in the reactor isolation of nanoparticles having a Specific particle size may dictate the particle size, with longer residence times distribution. Aggregated nanoparticles may be collected leading to larger particle sizes. The product is removed from through centrifugation, filtering, or other means of collecting the vessel 2 for further processing. The product may then be a Solid from a slurry. Selective eXtraction may be carried out Sprayed, purified, extracted, and/or size fractionated. using polar/nonpolar miscible Solvent pairs, including, but not limited to, chloroform/ethanol, or hexane/ethanol, or 0092 Products may be isolated and dried to remove the water/ethanol. Solvents and/or volatile reaction products. The dried prod ucts may then be redispersed in an appropriate Solvent, Such 0096. In other embodiments chromatography may be as chloroform or hexane. Alternative Solvents for redisper used to size fractionate nanoparticles of the present inven Sion include but are not limited to hydrocarbons, ethers, tion. Chromatography methods may be used to Separate alcohols, ketones, and compressed fluids Such as ethane, nanoparticles based on size, shape, charge, hydrophobicity, propane or carbon dioxide. In particular embodiments the or other characteristics that distinguish the nanoparticles. In capping agents may be tailored for redispersion in water, Some embodiments liquid chromatography may be used. carbon dioxide, fluorocarbons, and other organic and polar The liquid chromatography may be conducted at ambient Solvents. preSSures or at high preSSures using high pressure liquid chromatography (HPLC). The column may be packed with 0093. After the reaction is at least partially completed, the Size exclusion gel that separates Small unreacted byproducts reaction vessel may include a mixture of nanoparticles and from the larger particles. In other embodiments, the column unreacted organometallic precursors. If no Solvent is used, may consist of, but is not limited to, an ion eXchange resin, the nanoparticles may be dissolved or Suspended in the a reverse chromatography packing, or Silica. Any Suitable capping agent. If a Solvent is used, the nanoparticles may be size-exclusion or reverse-phase chromatographic packing dissolved or suspended in the solvent. The size distribution may be used for the Separation. In one embodiment, Bio of the nanoparticles is typically determined by the reaction BeadsTM, (Bio-Rad, Hercules, Calif.) may be used. conditions and reagents. To narrow the Size distribution of particles various separation techniques may be used. The 0097. In another embodiment, a flow process may be nanoparticles may be separated from the unreacted reagents used for the manufacture of nanoparticles. A flow proceSS by a variety of techniques. offers a way to produce nanoparticles continuously. FIG. 3 depicts a Schematic of an embodiment of a continuous flow 0094. In an embodiment, the nanoparticles may be iso production System. In an embodiment, continuous flow lated from the reaction compartment by flushing with a system 16 may include reactor 18, a first heater 19 coupled Solvent. The Solvent may be an organic Solvent, or a polar to reactor 18, a temperature monitor 20 coupled to reactor Solvent, depending on the nanoparticle Solubility. The reac 18, and injector 22 coupled to reactor 18. Reactor 18 may tor may be flushed once, or Several times, to remove the include inlet 24 and outlet 26. First heater 19 may function nanoparticle. Because nanoparticles have an average diam to control the temperature of the reactor during use. Tem eter of less than about 100 nm, the addition of a solvent perature monitor 20 may function to monitor the reaction causes the particles to become "dispersed” within the Sol temperature during use. Injector 22 may function to inject vent. When dispersed in a Solvent, the nanoparticles may the reagents into the reactor 18 at pressure greater than 1 exist as individual particles that are separated form other atm. nanoparticles by the solvent. Particles may be removed from 0098. In certain embodiments, reactor 18 may be a high the Solvent by treating with a Second Solvent. The Second preSSure reaction vessel. Certain embodiments use a Stain Solvent may induce aggregation of the nanoparticles. Aggre less steel cell (High Pressure Equip. Co., Buffalo, N.Y.), or gation of the nanoparticle may cause particles to associate an inconnel high pressure cell. Alternative high-pressure with each other to form aggregates of particles. These vessels may be used to carry out the methods of the aggregates may be filtered to remove the Solvent and other invention. Alternatives include, but are not limited to, iron impurities in the reaction mixture. based alloys and titanium. First heater 19 may be used to 0.095. During formation of nanoparticles, a nanoparticles control the temperature of reactor 18. In one embodiment, a having a large average particle size distribution may be first heater may be a heating tape. Other types of heaters obtained. In some embodiments, the size distribution of include, but are not limited to heating mantles, oil baths, particles may be narrowed by the choice of Solvents used for metal baths, resistive heaters, and hot air heaters. the isolation process. AS described above, nanoparticles may be dispersed in a solvent. The addition of a second solvent 0099. In an embodiment, reactor 18 may be of a length may induce aggregation of the nanoparticles. In Some Such that precursors decompose to form nanoparticles dur embodiments, the Second Solvent may induce only a portion ing the time the precursors are in reactor 18. The flow rate of the nanoparticle having a narrow particle size distribution of the precursors and capping agents may be adjusted to to be isolated. For example, if the nanoparticles formed after ensure the reaction runs to completion. reaction of the organometallic precursor have a average 0100 Temperature monitor 20 may be coupled to reactor particle size ranging from 1 to about 100 nm, the addition of 18 and include a device for observing the temperature of the a Second Solvent may induce aggregation of only nanopar reaction within reactor 18. The temperature monitor should US 2003/0003300 A1 Jan. 2, 2003 also be capable of withstanding the potentially harsh con nanoparticle Surface. In other embodiments the nanoparticle ditions therein. A non-limiting example of a temperature cores may be bonded covalently through an Si-C linkage. monitor is a platinum resistance thermometer. The nanoparticles may have residual oxygen, or Sulfur on 0101. In an embodiment, continuous flow system 16 may their Surfaces. The nanoparticles typically luminesce with also include mixing chamber 28. Mixing chamber 28 may be size-tunable color, from the blue (approximately 15 A coupled to inlet 24 and may include second heater 29 diameter for Silicon nanoparticles) to green (approximately functioning to preheat precursor, capping agent, and Solvent 25 to 40 A diameter for silicon nanoparticles) into the before injecting the mixture into reactor 18. Injector 22 may yellow, orange and red for particles that can be in up to 80 be coupled to mixing chamber 28 and function to inject the Ain diameter. The nanoparticles may exhibit charge transfer Solvent into mixing chamber 28 at the appropriate pressure. between neighboring particles. Typically, the emission color Mixing chamber 28 may include a second heater which may depends also on the excitation energy, either by photo or function to control the temperature of mixing chamber 28. electrical means. One skilled in the art may envision numerous means of 0106. In one embodiment, nanoparticles may be stimu controlling the temperature of mixing chamber 28 known to lated So as to emit light. Discrete optical transitions also may the art. appear in the absorbance and photoluminescence excitation (PLE) spectra of the nanoparticles, which is generally con 0102 Continuous flow system 16 may include injector Sistent with quantum confinement effects in Semiconductors. 22. In Some embodiments, injector 22 may be coupled to The particle distribution is typically within a standard devia reactor 18, in other embodiments injector 22 may be coupled tion about the mean particle diameter. The appearance of to mixing chamber 28, or in other embodiments injector 22 discrete optical transitions, or peaks, in the absorbance may be coupled to mixing chamber 28 and reactor 18. When and/or luminescence Spectra typically indicates a narrow injector 22 is coupled to mixing chamber 28 and reactor 18 Size distribution, as the optical properties of the nanopar there may exist a System for controlling the flow from ticles themselves are size-dependent. Furthermore, the injector 22 to mixing chamber 28 and reactor 18. Injector 22 appearance of discrete peaks typically indicates the homo may function to transfer a Solvent over a range of pressures geneous chemical nature of nanoparticles, including core necessary to Solvate the nanoparticles precursors and the chemistry, crystallinity, Surface chemistry and chemical cov capping agent. Injector 22 may include tube 30 and pump erage. In certain embodiments particle size distribution may 32. Tube 30 may include a moveable member or piston 34 affect the appearance of discrete transitions in the optical positionable within tube 30 and adapted to inhibit material Spectra. Typically in these Small particles, the energy levels from moving within tube 30 from one side of piston 34 to have separated Significantly compared to bulk silicon, mak another side of piston 34. Pump 32 may function to transfer ing these transitions observable, an effect of quantum con material including a fluid or a gas in an end of tube 30 on one finement. In certain embodiments particle Surface chemistry Side of piston 34. The fluid or gas may exert a force on may affect the appearance of discrete transitions in the positionable piston 34, moving piston 34 and Subsequently optical Spectra and may broaden the PL emission energies. exerting a force on a Solvent located in tube 30 on an opposite Side of piston 34. 0107. In some embodiments, nanoparticles may exhibit previously unobserved discrete electronic absorption and 0103) In some embodiments, continuous flow system 16 luminescence transitions due to quantum confinement may be Sealed from outside contamination and under an effects. Nanoparticles described herein may exhibit discrete inert atmosphere. Use of an inert atmosphere may reduce the electronic absorption and luminescence transitions due to extent of incidental oxidation of the Surface of the crystalline quantum confinement effects that are dependent upon the composition. Size of the nanoparticles. Differences in the discrete optical 0104 FIG. 2 illustrates an example of sterically stabi properties due to differences in the Size of the nanoparticles lized nanoparticles 12. Shown in FIG. 2 are capping agents may translate into differently sized nanoparticles emitting 14 coupled to the nanoparticles. Capping agents 14 may be light at different wavelengths and colors. Several non lim flexible organic molecules, alkanes are a non-limiting iting examples include: Silicon nanoparticles with an aver example, that typically provide repulsive interactions age diameter of about 2 nm emitting a blue light, Silicon between nanoparticles 12 in Solution. The repulsive nature nanoparticles with an average diameter of about 3.5 nm of capping agents 14 typically prevents uncontrolled growth emitting a green light, Silicon nanoparticles with an average and aggregation of nanoparticle 12. Generally, the core of diameter of about 4.5 nm emitting a yellow light, Silicon nanoparticle 12 tends to be well defined and faceted. How nanoparticles with an average diameter of about 6 mm ever, in other embodiments, the particles may be spherical or emitting an orange light; and Silicon nanoparticles with an ellipsoidal. In one embodiment, the nanoparticle core may average diameter of about 7-8 nm emitting a red light. In be amorphous. certain embodiments, the Surface chemistry may shift the emission energies to slightly lower values. For example, 2 0105 Nanoparticles produced using the method nm Silicon nanoparticles may emit green light, or even in the described herein may be structurally, chemically, and opti case of very heavy Surface oxidation, for example, although cally characterized. For example, nanoparticles may be the Surface coating is not limited to oxygen, these particles characterized by transmission electron microscopy (TEM), may emit orange or red light. Studies confirm that Silicon energy-dispersive X-ray spectroscopy (EDS), Fourier trans clusters as small as 15 A may behave as indirect Semicon form infrared spectroscopy (FTIR), UV-visible absorbance, ductors. The method for nanoparticle formation may be and luminescence (both PL and PLE) spectroscopy data. In applied to other materials, Such as nanowires, that typically certain embodiments, nanoparticles may be crystalline cores require temperatures greater than the boiling point of avail coated by hydrocarbon ligands bound through covalent able Solvents under ambient pressure, typically greater than alkoxide bonds or interactions of a thiol group with the 350 C., for crystal formation. Absorbance of the composi US 2003/0003300 A1 Jan. 2, 2003 tions may range from approximately 1000 nm to approxi an electrode (for example, Pt), which then react in Solution mately 350 nm. In particular embodiments, the compositions to give the excited State R* as illustrated in reaction 1 and may be excited electronically. The compositions may dis 2 herein. This property may form the basis for sensor play photoluminescence at 300 nm to 1000 nm. Generally, technologies. photoluminescence decays by less than 50% when exposed 0112 Nanoparticles of other metals may be formed by to the atmosphere for 30 days. In particular embodiments of heating organometallic precursors in the presence of a the invention the size of nanoparticles typically produced are capping agent. For example, Group II-VI and Group III-V in the approximate range of 10 A to 200 A and larger. In nanoparticles may also be prepared by using methods simi other embodiments the size of the nanoparticles typically lar to those described above for Group IV metals. Addition produced are in the approximate range of 15 to 40 A. Size ally, nanoparticles of Group II, Group III, Group V, and distributions that display discrete optical transitions typi Group VI metals may be formed using methods similar to cally are 15 to 25 A and may be luminescent at 350 to 500 those described above for the Group IV metals. In one . embodiment, nanoparticles may be formed by reacting one 0108. In some embodiments, nanoparticles may exhibit or more organometallic precursors in the presence of a Shorter photoluminescence lifetimes than those previously capping agent. The organometallic precursors and capping observed for the same element. For example, porous Silicon agent may be heated at a pressure greater than 1 atm. in a and oxide capped Silicon nanoparticles have previously reaction vessel. Heating of the organometallic precursors exhibited microSecond Scale photoluminescence lifetimes. results in the thermal degradation of the organometallic Examples of Silicon nanoparticles formed by methods precursor, which in turn leads to the formation of nanopar described herein exhibit a photoluminescence lifetime ticles. The precursors may degrade through a free radical (greater than 96% of the total photoluminescence lifetimes) mechanism, or it may degrade through thermolysis. The of less than or equal to 20 ns. An example of an octanethiol capped Silicon nanoparticles exhibits characteristic lifetimes dimensions of the nanoparticles may be controlled by reac with a fast component (~100 picoseconds) and two slow tion conditions and the capping agent used. The reaction components with lifetimes ranging from 2 to 6 ns. The slow conditions used to control the particle size may include, for components photoluminescence lifetimes observed for the example, the temperature, pressure, precursor concentration, octanethiol-capped Silicon nanoparticles example are at least capping ligand concentration, Solvent, precursor composi three orders of magnitude faster than those previously found tion and capping agent composition. In one embodiment a for porous Silicon and Silicon nanoparticles. The measured free radical initiator may be added to the reaction. It is lifetime relates to the radiative and non-radiative electron believed that the capping agent may aid in controlling the hole recombination processes. Faster electron-hole recom dimensions of the formed nanoparticles by inhibiting growth bination processes may be better for certain applications of the nanoparticles. The capping agent may also prevent Such as light emitting devices or light emitting diodes reactive degradation of the nanoparticles when exposed to (LEDs) and optical Switches. Coating the nanoparticles with water and oxygen and other chemical contamination. a different wider band gap Semiconductor, Such as CdS or ZnS, may reduce the non-radiative rates. Coating the nano 0113 A Group II organometallic precursor may be a particles with a Smaller band gap Semiconductor like Ge Group II metal that includes organic groups. AS used herein may increase the photoluminescence lifetime in the par a “Group II metal' includes the elements of Zinc, cadmium, ticles. For certain applications, the photoluminescence life and mercury. Group II organometallic precursors include, time may be increased through the use of different capping but are not limited to organozinc, organocadmium and ligands. organomercury compounds. Some examples of Group II 0109 Nanoparticles described herein may be relatively organometallic precursors include, but are not limited to, Stable when charging the nanoparticles with electrons or alkylzincS, alkylcadmiums, alkylmercurys, arylzincS, aryl electron holes. Stability of the nanoparticles during charging cadmium and arylmercury. Examples of organometallic Zinc with electrons and electron holes may make the nanopar precursors include, but are not limited to, dimethyl Zinc, ticles Suitable for floating gate memory. In another embodi diethyl Zinc, and diphenyl Zinc. Examples of organometallic ment, Stability of the nanoparticles during charging may cadmium precursors include, but are not limited to, dimethyl make these materials Suitable for photocatalytic or battery cadmium, diethyl cadmium, and diphenyl cadmium. applications. Examples of organometallic mercury precursors include, but 0110 Nanoparticles described herein may exhibit quan are not limited to, dimethyl mercury, diethyl mercury, and tized, or discrete,charging. Quantized charging may allow diphenyl mercury. Organometallic Zinc and organometallic for use of the nanoparticles in multi-valued logic applica mercury precursors may be formed by the reaction of tions. The nanoparticles may exhibit reversible multiple metallic mercury or Zinc with an alkyl or aryl halide by charge transferS. Reversible charge transferring of nanopar known methods. Organometallic cadmium precursors may ticles may allow for light emission by charge injection, or be formed by the reaction of cadmium halides with Grignard electrogenerated chemiluminescence. The nanoparticles reagents (e.g., RMgX) by known methods. may emit light under repetitive electrode potential cycling or 0.114) A Group VI organometallic precursor may be a pulsing between nanoparticles oxidation and reduction. In Group VI metal that includes organic groups. AS used herein electrogenerated chemiluminescence experiments, electron a “Group VI metal' includes the elements of selenium transfer annihilation of electrogenerated anion and cation tellurium. Group VI organometallic precursors include, but radicals results in the production of excited States: are not limited to organoSelenides, organotellurides. Some R-R-R*--R (1) examples of Group VI precursors include, but are not limited R*->R+hw (2) to, dialkylselenides, dialkyltellurides, diarylselenides, dia 0111. In this case, RT and R" refer to negatively and ryl tellurides, dialkyldiselenides, dialkylditellurides, diaryld positively charged Silicon nanoparticles electrogenerated at iselenides, diarylditellurides,. Examples of organometallic US 2003/0003300 A1 Jan. 2, 2003

Selenium precursors include, but are not limited to, dimeth the Solvent, the capping agent, or both the Solvent and the ylselenide, diethylselenide, diphenylselenide, dimethyldis capping agent. The Solvent and capping agent are as defined elenide, diethyldiselenide, and diphenyldiselenide. previously. Examples of organometallic tellurium precursors include, 0118 Nanoparticles of any of the Group II, III, IV, V or but are not limited to, dimethyltelluride, diethyltelluride, VI may be formed as described above. In another embodi diphenyltelluride, dimethylditelluride, diethylditelluride, ment, nanoparticles composed of mixtures of Group II, III, and diphenylditelluride. Organometallic Selenium and tellu IV, V, and VI. Mixtures include mixtures within a group and rium precursors may be formed by the reaction of Sodium mixtures between groups. Mixtures within in a group may be Selenide or sodium telluride with alkyl or aryl halides by formed by heating two or more organometallic precursors of known methods. the same group in the presence of a capping agent. For example, Silicon-germanium nanoparticles may be formed 0115 A Group III organometallic precursor may be a by heating a mixture of a Silicon organometallic precursor Group III metal that includes organic groups. AS used herein (e.g., diphenylsilane) and a germanium organometallic pre a “Group III metal' includes the elements of boron, alumi cursor (e.g., diphenylgermane), a capping agent, and, num, gallium, indium, and thallium. Group III organome optionally, a Solvent. In one embodiment, the reaction is tallic precursors include, but are not limited to organogal conducted at Supercritical conditions. The decomposition of lium compounds, organoindium compounds, and the organometallic precursors may lead to formation of organothallium compounds. Some examples of Group III Silicon-germanium nanoparticles. precursors include, but are not limited to, trialkylgallium compounds, trialkylindium compounds, trialkylthallium 0119). In another embodiment, nanoparticles that include compounds, triarylgallium compounds, triarylindium com mixtures of elements from different groups may be formed. pounds, triarylthallium compounds. Examples of organome One common group of Semiconductor materials are the tallic gallium precursors include, but are not limited to, Group II-VI semiconductors. These materials are typically trimethylgallium and triphenylgallium. Examples of orga composed of mixtures of Group II metals and Group VI nometallic thallium precursors include, but are not limited metals. Group II-VI nanoparticles may be formed by heating to, trimethylthallium and triphenylthallium. Examples of a mixture of one or more Group II organometallic precur organometallic indium precursors include, but are not lim Sors, one or more Group VI organometallic precursors, a ited to, trimethylindium and triphenylindium. Organometal capping agent, and, optionally, a Solvent. Decomposition of lic gallium, indium, and thallium precursors may be formed the organometallic precursors may lead to Group II-VI by the reaction of the appropriate metal halide (e.g., GaCl, nanoparticles. In one embodiment, the reaction is conducted InCls, or TICl) with Grignard reagents (e.g., RMgX) or at Supercritical conditions. For example, cadmium-selenide trialkyl- or triaryl aluminum compounds by known methods. nanoparticles may be produced by heating a mixture of a cadmium organometallic precursor (e.g., dimethyl cad 0116 A Group V organometallic precursor may be a mium) and a Selenium organometallic precursor (e.g., diphe Group V metal that includes organic groups. AS used herein nyldiselenide) in the presence of a capping agent. a “Group V metal' includes the elements of phosphorus, arsenic, and antimony. Group V organometallic precursors 0120 Group Ill-V nanoparticles may be formed by heat include, but are not limited to organophosphorus com ing a mixture of one or more Group III organometallic pounds, organoarsenic compounds, and organoantimony precursors, one or more Group V organometallic precursors, compounds. Some examples of Group III precursors a capping agent, and, optionally, a Solvent. Decomposition include, but are not limited to, trialkylphosphorus com of the organometallic precursors may lead to Group Ill-V pounds, trialkylarsenic compounds, trialkylantimiony com nanoparticles. In one embodiment, the reaction is conducted pounds, triarylphosphorus compounds, triarylarsenic com at Supercritical conditions. For example, gallium-arsenide pounds, triarylantimony compounds. Examples of nanoparticles may be produced by heating a mixture of a organometallic phosphorus precursors include, but are not gallium organometallic precursor (e.g., trimethyl gallium) limited to, trimethylphosphine and triphenylphosphine. and an arsenic organometallic precursor (e.g., trimethyl Examples of organometallic arsenic precursors include, but arsenide) in the presence of a capping agent. In another are not limited to, trimethylarSenide and triphenylarSenide. example, Indium-gallium-arsenide nanoparticles may be Examples of organometallic antimony precursors include, formed by heating a mixture of a gallium organometallic but are not limited to, trimethylantimony and triphenylan precursor (e.g., trimethyl gallium). an arsenic organometal timony. Organometallic phosphorus compounds are com lic precursor (e.g., trimethyl arsenide) and an indium orga mercially available Organometallic gallium, indium, and nometallic precursor (e.g., trimethyl indium) in the presence thallium precursors may be formed by the reaction of the of a capping agent. Other materials that may be formed appropriate metal halide (e.g., GaCl, InCls, or TICl) with include, but are not limited to, indium-phosphide, indium Grignard reagents (e.g., RMgX) or trialkyl- or triaryl alu areSenide, and gallium-phosphide. minum compounds by known methods. 0121 Group IV-V nanoparticles may be formed by heat 0117 Nanoparticles may be formed by taking one or ing a mixture of one or more Group IV organometallic more of the Group II, III, IV, V, or VI organometallic precursors, one or more Group V organometallic precursors, precursors and heating them in the presence of a capping a capping agent, and, optionally, a Solvent. Decomposition agent. In one embodiment, the organometallic precursor and of the organometallic precursors may lead to Group IV-V the capping agent may be reacted at Supercritical conditions. nanoparticles. In one embodiment, the reaction is conducted The reaction may be conducted at or above the critical point at Supercritical conditions. For example, phosphorus doped of the capping agent. Alternatively, a Solvent may be used. Silicon nanoparticles may be produced by heating a mixture The reaction may be conducted above the critical point of of a silicon organometallic precursor (e.g., diphenylsilane) US 2003/0003300 A1 Jan. 2, 2003 and a phosphorus organometallic precursor (e.g., triphenyl water the predominant product is a copper nanoparticle. phosphine) in the presence of a capping agent. Additionally, the addition of an oxidant or reducing agent may influence the products produced. Other factors, includ 0.122 Group IV-III nanoparticles may be formed by heat ing but not limited to, precursor concentration, Solution pH, ing a mixture of one or more Group IV organometallic and capping ligand may affect the crystal Structure, Size, precursors, one or more Group III organometallic precur morphology, and degree of agglomeration of the nanopar Sors, a capping agent, and, optionally, a Solvent. Decompo ticles. Metal alloy nanoparticles may be made by hydrolyZ Sition of the organometallic precursors may lead to Group ing mixtures of metal Salts. IV-III nanoparticles. In one embodiment, the reaction is conducted at Supercritical conditions. For example, boron 0.126 Nanoparticles may be modified by further treat doped Silicon nanoparticles may be produced by heating a ment after they have been formed. For example, Silicon or mixture of a silicon organometallic precursor (e.g., diphe germanium nanoparticles may be modified after Synthesis nylsilane) and a boron organometallic precursor (e.g., triph using Standard ion implantation techniqueS or ion diffusion enylborane) in the presence of a capping agent. techniques. For example, Silicon nanoparticles may be doped by ion implantation of phosphorus to form n-type 0123 Group IV nanoparticles that are doped with rare Semiconductor materials. earth elements may also be formed by heating one or more Group IV organometallic precursors, one or more rare earth 0127. Additionally, nanoparticles may be further modi elements, a capping agent, and, optionally, a Solvent. fied by additional growth after Synthesis. For example, after Decomposition of the organometallic precursors may lead to formation of a nanoparticle, a coating layer having the same Group IV nanoparticles that are doped with one or more rare composition or a different composition may be formed on earth elements. In one embodiment, the reaction is con the nanoparticle. The coating composition may be formed by ducted at Supercritical conditions. Rare earth elements placing the nanoparticles in the presence of a coating include lanthanum, cerium, praseodymium, neodymium, precursor. The coating precursor may be an organometallic promethium, Samarium, europium, gadolinium, terbium, precursor. Upon decomposition of the organometallic pre dySprosium, holmium, erbium, thulium, ytterbium, and lute cursor, the material may form a coating on the nanoparticle. tium. For example, ytterbium doped Silicon nanoparticles Growth of the coating may be regulating by the presence of may be produced by heating a mixture of a Silicon organo capping agents, as described above. For example, germa metallic precursor (e.g., diphenylsilane) and an ytterbium nium nanoparticles may be coated with a Silicon coating precursor in the presence of a capping agent. layer. The Silicon coating layer may be grown on the germanium nanoparticle using Standard deposition tech 0.124. Other metal precursors of other metal groups niques. Alternatively, the silicon may be grown on the (including the transitional metals) may be heated to form germanium nanoparticle by placing the nanoparticle in a nanoparticles. Many complexes of metals with Small organic reactor and treating the particle with an organometallic molecules and carbon monoxide may be formed. For Silicon precursor. Upon decomposition of the organometallic examples, many metals may form complexes with one or Silicon precursor, Silicon may form a coating on the germa more cycopentadienes to form metallocenes. Many metal nium particle. The thickness of the coating may be con locenes exhibit Some Solubility in organic Solvents. Metal trolled by the reaction conditions used and the nature of the locenes may be decomposed by heating to high tempera capping agent. tures. When heated to high temperatures in the presence of a capping agent, and, optionally a Solvent nanoparticles may 0128 Applications be formed. In Some embodiments, the reaction is conducted above the Supercritical point of the capping agent and/or Floating Gate Memory Solvent. Examples of metallocenes include, but are not 0129. In some embodiments, nanoparticles may be used limited to, ferrocene, cobaltocene, nickelocene, titanocene in floating gate or flash memory applications. Non-volatile dichloride, Zirconocene dichloride, and uranocene. When memory Such as electrically programmable read-only decomposed these metallocenes may lead to iron, cobalt, memory (EPROM) and electrically-erasable programmable nickel, titanium, Zirconium, or uranium nanoparticles read-only memory (EEPROM) are used for storing data in respectively. The formation of metal nanoparticles may be computer systems. EPROM and EEPROM memory includes aided by the addition of a reducing agent. Reducing agents a plurality of memory cells having electrically isolated include, but are not limited to, hydrogen and hydride com gates, referred to as floating gates. Data is Stored in the pounds. Hydride compounds include, but are not limited to, memory cells in the form of a charge on the floating gates. lithium aluminum hydride, lithium borohydride, and sodium Charge is transported to or removed from the floating gates borohydride. by program and erase operations, respectively. 0.125 Metal salts may also be used as precursors for the formation of metal nanoparticles and/or metal oxide nano 0.130. Another type of non-volatile memory is flash particles. In one embodiment, metal Salts (e.g., metal nitrates memory. Flash memory is a derivative of EPROM and and metal acetates) may be hydrolyzed in Supercritical water EEPROM. Although flash memory shares many character to form nanoparticles of the metal or metal oxide nanopar istics with EPROM and EEPROM, the current generation of ticles. Capping agents may be used to control whether a flash memory differs in that erase operations are done in metal nanoparticle or a metal oxide particle may be formed. blocks. For example, copper nitrate may be decomposed in Super 0131) A typical flash memory includes a memory array critical water to form copper (I) oxide nanoparticles in the composed of a plurality of memory cells arranged in row and absence of a capping agent. When a capping agent (e.g., column fashion. Each of the memory cells includes a float 1-hexanethiol) is added to copper nitrate in Supercritical ing gate field-effect transistor capable of holding a charge. US 2003/0003300 A1 Jan. 2, 2003

The cells are usually grouped into blocks. Each of the cells quantized charging. Quantized charging means that electron within a block may be electrically programmed in a random injection may occur as discrete charging events with discrete basis by charging the floating gate. The charge may be threshold Voltages. Quantized charging may allow for use of removed from the floating gate by a block erase operation. the nanoparticles in multi-valued logic applications. The The charge may be negative or positive. The data in a cell nanoparticles may exhibit reversible multiple charge trans is determined by the presence or absence of the charge in the fers. Traditional memory units only have two different logic floating gate. states usually represented as '0' and 1. Memory devices including nanoparticles described herein may be capable of 0132) Flash memories have the potential of replacing attaining more than two logic States due to the nanoparticles hard Storage disk drives in computer Systems. The advan ability to exhibit quantized charging. The basic design of tages would be replacing a complex and delicate mechanical System with a rugged and easily portable Small Solid-State memory devices is described in further detail in U.S. Pat. non-volatile memory System. There are also the possibilities No. 6,331,463 B1 which is incorporated herein by reference. that flash memories might be used to replace DRAMs. Flash 0.136. In some embodiments, the particles forming the memories have very high potential densities and more speed floating gate 44 will be size-monodisperse with Standard of operation, particularity in the erase operation, than deviations approximately less than 10% about the mean DRAMS. Flash memories might then have the ability to fill diameter. These particle may organize Spatially into a lattice. all memory needs in future computer Systems. In one embodiment, two or more distinct particle sizes will form the floating gate 44. These particles may organize 0.133 FIG. 4 depicts an embodiment of a floating gate Spatially into bidisperse particle arrayS. The particles mak field effect transistor or floating gate memory device 36. ing up the floating gate 44 may be deposited by Spin-coating, Floating gate memory device 36 may include Source 38, Spraying from Solution, Spraying through the rapid expan drain 40, control gate 42, and floating gate 44. Source 38 Sion from Supercritical Solution (RESS), or drop casting. The may be formed from an N+ type of high impurity concen particles in the floating gate 44 may be embedded in a tration. Drain 40 may be formed from an N+ type of high conducting, or an insulating, polymer. In another embodi impurity concentration. Source 38 and drain 40 may be ment, the particles may be embedded in a thin gate oxide. In formed in substrate 46. Substrate 46 may be formed of a one embodiment, the particles making up the floating gate P-type Semiconductor of low impurity concentration. 44 might be evaporated and deposited from an aeroSol. In 0134. In some embodiments, source 38 and drain 40 may embodiments with the floating gate 44 consisting of distinct be separated from one another by a channel 48. Channel 48 classes of sizes, for example, a bimodal size distribution of may function as a conduit for electron flow. In one embodi particles, discrete charging events may occur due to the size ment, the channel will be a Group IV nanowire. Floating dependence of the Coulomb charging of the particles. The gate 44 may be positioned between channel 48 and control term Coulomb charging refers to the repulsion between gate 42. Floating gate 44 may be electrically isolated. Data electrons within the nanoparticle core due to the Small size can be written into floating gate memory device 36 by of the particles. Coulomb charging leads to discrete Voltage injecting electrons through channel 48 or Substrate 46 into dependent charging events, and may be utilized for multi floating gate 44. Reversing the flow of electrons Sends valued logic applications, or other digital applications that electrons out of floating gate 44 erasing the Stored data. use information Stored as memory States higher than binary. Writing data to non-volatile memory may function differ A floating gate 44 may consist of a bimodal size distribution ently beginning by Setting up an electric field acroSS barrier of nanoparticles, either the Group IV particles described layer 50 to attract electrons in channel 48. In another herein, or possibly other nanoparticle materials, including embodiment, energy may be Supplied to the electrons to ferromagnetic particles and ferroelectric particles. overcome the barrier 50. Either method may increase the threshold Voltage of the floating gate memory device 36. Light Emitting Devices Variation of the threshold Voltage caused by the change in 0.137 Other applications using nanoparticles exhibiting Stored electric charges within floating gate 44 can represent discrete optical properties may include light emitting different logic States, non limiting examples are 0 and 1. devices and applications thereof. Specific interest has been To erase Stored data in a non-volatile memory device a high focused on the development of inexpensive and efficient electric field may be set up between Source 38 and control light emitting diodes (LEDs). gate 42. Consequently, electrons trapped in floating gate 44 can now penetrate neighboring barrier layer 50 causing the 0.138 Light emitting devices such as light emitting threshold voltage to drop. This change in the threshold diodes (LEDs) have been constructed in the past using Voltage may represent another logic State. P-doped and N-doped materials. However, such devices are generally only capable of emitting color of a particular 0135) In some embodiments, floating gate 44 may wavelength based on the Semiconductor materials used in include the nanoparticles described herein. The nanopar the diode. Light emitting devices have also been made using ticles may be used as discrete nanoparticles. In another a polymeric material Such as poly-(p-phenylene vinylene) embodiment the nanoparticles may be spin-coated as a thin (PPV) as a hole transport layer between a hole injection film to form floating gate 44. In another embodiment the electrode and an electron injection electrode. However, Such nanoparticles may be drop cast as a thin film to form floating devices are also limited to emission of a Single color, based gate 44. In one embodiment, an oxide, or other dielectric on the type of light emitting polymeric material utilized. material may be grown over the particles. In another Thus, to vary the color, one must use a different polymer, embodiment, an insulating polymer or other organic which prevents, or at least complicates, the display of light molecular material might be laid on top of the particles of various colors. Furthermore, Since Such polymeric mate forming the floating gate 44. The nanoparticles may exhibit rials do not function as electron transport media, the recom US 2003/0003300 A1 Jan. 2, 2003

bination of holes and electrons, which results in Such light herein. light emitting device 52 may include first electrode emission, occurs adjacent the electron injection electrode, 54, second electrode 56, and emissive layer 58. Emissive which tends to lower the efficiency of the device as a light layer 58 may include the nanoparticles exhibiting discrete SOCC. optical properties as described herein. Emissive layer 58 0139 Nanoparticles may be used in the formation of the may include a polymer wherein the nanoparticles may be emissive layer in LEDS. In one embodiment, Silicon nano Suspended. However, nanoparticle based light emitting particles may be used in a light emitting diode System. devices 52 may not require a polymer to emit, in contrast to Silicon at nanometer dimensions has different properties many organic LEDs. PolymerS may inflict losses through than bulk silicon used in Semiconductor chips. Bulk silicon absorption, Scattering, and poor electron-hole interfaces. does not emit light, while, Silicon nanoparticles at the Sub-10 Emissive layer 58 may be positioned adjacent first electrode nm level may exhibit luminescence over the entire visible 54. First electrode 54 may function as a cathode. Emissive Spectrum. The Specific wavelength emitted by the Silicon layer 58 may be positioned adjacent second electrode 56. nanoparticles may be dependent on the size of the particles. Second electrode 56 may function as an anode. For example, 1.5 nm Silicon nanoparticles emit blue light; 8 0143. In an embodiment, second electrode 56 may nm Silicon nanoparticles emit red light. include substrate 60. Substrate 60 may include a transparent 0140. In an embodiment, running a current across an conductive oxide layer. Non-limiting examples of the trans ordered distribution of nanoparticles having particles having parent conductive oxide layer may include indium tin oxide, a average particle diameter between about 1.5 nm to about tin oxide, or a translucent thin layer of Ni or Au or an alloy 8 nm. In one embodiment, variations in Voltage, however, of Ni and Au. The basic design of light emitting devices is may not effect the color of the light emitted by the nano described in further detail in U.S. Pat. No. 5,977.565 which particles. This embodiment may consist of a device with is incorporated herein by reference. size-monodisperse nanoparticles-i.e., particles with a stan 0144. In an embodiment, the nanoparticles may emit light dard deviation about the mean diameter of 50% or less, or by optical Stimulation. In this device, an optical excitation 20% or less, or 5% in Some cases. In another embodiment, Source is used in place of electrical Stimulation. However, in a device may emit Voltage-tunable color. This device may another embodiment, a combination of optical excitation consist of a mixture of particle sizes. One example device and electrical Stimulation may be used to enhance device might consist of a bimodal size distribution. Another performance, Such as overall energy efficiency or perhaps example device might have bimodal nanoparticles that are color tenability. Spatially organized with either the Small particles closer to the anode and the larger particles closer to the cathode, or the Small particles closer to the cathode and the larger particles LaserS closer to the anode. In one embodiment, the color of the 0145 An extension of the application of nanoparticles in emission is Voltage tunable due to charge transfer between light emitting devices is the use of nanoparticle based light the nanoparticles and the polymer. In this device, the par emitting devices for coherent light generation and optical ticles may be embedded in the polymer layer. In one gain applications. The basic problem impeding the efficient embodiment, the nanoparticles may be Sandwiched between operation of optically-pumped Solid-State laserS is that the a hole transporting layer and an electron transporting layer. typical Solid-State laser materials consist of a wide bandgap The charge transporting layerS may be conducting polymers, insulating host material doped with optically active impurity or conducting Small molecules, or molecular crystals. In one atoms. The impurities are typically either rare-earth ions embodiment, a gate electrode Serves to modulate the color of (Nd.Sup.3+, Er.Sup.3+) or the transition metals ions light emission from the particles. A gate electrode may be (Cr.Sup.3+, TiSup.3+). The absorption spectrum of Such ions used to improve the efficiency of light emission in another is characterized by the lines associated with the transitions embodiment. between the shielded (and thus narrow) for d atomic levels. 0.141. In one embodiment, a light may be formed having However, most of the pump Sources for Such lasers, Such as a broad size distribution of silicon nanoparticles. The broad high pressure gas discharge or incandescent lamps, are Size distribution may be advantageous in that the combina characterized by their extremely wide emission Spectrum. tion of wavelengths emitted by the different size particles Therefore, only a Small percentage of the pumped light is may produce a white light. The Silicon nanoparticles may be actually absorbed by the laser material. For a small diameter embedded in a polymer matrix. The polymer matrix is not, laser rod, this is typically less than 10%. As a result, the however, necessary for the Silicon nanoparticles to function flashlamp pumped Solid-State laser usually requires a bulky effectively as the emissive layer. The size distribution of power Supply and a water cooled System. Besides ineffi Silicon nanoparticles may allow the emission of white light. ciency, this renders the laser System useleSS for applications The nanoparticles themselves may emit with Size-indepen where portability is a key requirement. dent quantum yields and lifetimes. Clusters of nanoparticles 0146 In recent years, the laser diode has emerged as a may produce a broad emission band. If energy transfer promising alternative to flashlamp pumping of Solid-State occurs between neighboring nanoparticles, it does not result lasers. The high pumping efficiency compared to flashlamps, in the Selective emission from only the largest particles with stems from the better spectral match between the laser-diode the lowest energy gap between the highest occupied and emission and the rare-earth absorption bands. As a result, the lowest unoccupied molecular orbits (HOMO and LUMO). thermal load on both the laser rod and the pump is reduced. This situation is qualitatively different than known technol The System weight and power consumption are also Sub ogy using CdSe nanoparticles. stantially reduced with increased reliability. However, the 0142 FIG. 5 depicts an embodiment of a basic design for cost of the diode laser arrays makes it expensive. In addition, light emitting device 52 including nanoparticles as described the laser diodes require high current power Supplies that are US 2003/0003300 A1 Jan. 2, 2003

usually heavy rendering the lasers impractical for airborne larger Size than the Second layer, with the result that the third and Space applications. Therefore, Scientists have been try layer will be more absorptive of shorter wavelength radia ing to harness an alternative energy pump Source. tion than the Second layer. Finally fourth nanoparticle layer 80 (positioned between the third layer and substrate 82) may 0147 In response to the need for a more practical and have the largest nanoparticle sizes and thus will have an efficient energy pump Source the light emitting devices absorption edge at the shortest wavelengths (which tend to based on the nanoparticles described herein may be used. In penetrate deeper). In this way, more of the energy of the an embodiment, the nanoparticles may emit light by optical incident radiation from lamp 88 will be absorbed thereby Stimulation. In this device, an optical excitation Source is improving the absorption efficiency of the System. used in place of electrical Stimulation. Optical excitation Sources may include natural Sources Such as Sunlight or from 0152. In other embodiments there may be fewer nano manmade Sources, for example flashlamps. However, in particle layers 80 (for example, 1, 2, or 3) or there may be another embodiment, a combination of optical excitation more than four nanoparticle layers 80. The narrower the and electrical Stimulation may be used to enhance device bandwidth of lamp 88, the fewer nanoparticle layers 80 performance, Such as overall energy efficiency or perhaps necessary. In other embodiments there may be only one color tenability. Other Sources of excitation include an nanoparticle layer 80 including a wide distribution of size electron beam from, for example, an electron gun. ranges to absorb a broader bandwidth of light. Nanoparticle 0.148. In some embodiments, the nanoparticles may layers 80 may be oriented in any direction and not neces include doping agents to increase efficiency. Examples of sarily the direction depicted in FIG. 9. appropriate doping agents include rare earth ions and tran 0153. In other embodiments, an excitation source may be Sition metal ions. used to assist the nanoparticle layer(s) to emit light. The 0149. In certain embodiments, the nanoparticles may be excitation Source may include any type of energy capable of coated or embedded in materials acting as a Support for the inducing the nanoparticles to emit light. Non limiting nanoparticles. The Support material may have a lower refrac examples of an excitation Source are flashlamps, Sunlight, tive indeX than that of the nanoparticles. The Support mate and electricity rial may also be transparent to the exciting radiation. 0154 FIG. 10 depicts an embodiment of a basic design for a laser using an electrical excitation Source. This embodi 0150 FIG. 9 depicts an embodiment of a basic design for ment traps light in an optical cavity as described herein for laser assembly or coherent light emitting device 78. Laser the embodiment depicted in FIG. 9. The difference is that assembly 78 may include nanoparticle layers 80, Substrate the nanoparticles are not excited optically but electrically. In 82, mirrors 84 and 86 and lamp 88. Nanoparticle layers 80 this embodiment a devise similar to light emitting device 52 may be positioned on Substrate 82. Substrate 82 may act as described herein and depicted in FIG.5 may be incorporated a support base for nanoparticle layers 80. Mirrors 84 and 86 to emit the light which is trapped in the optical cavity. Light may form an optical cavity for laser assembly 78. Mirror 84 emitting device 52 may be electrically coupled to a power may be reflective towards radiation on the right Side, effec tively 100%. The left side of mirror 84 may or may not be source (not shown). Multiple light emitting devices 52 may reflective to assist in controlling radiation entering the form an array between mirrors 84 and 86. light emitting optical cavity. Mirror 86 may be slightly transparent (about devices 52 may be oriented in any direction and not neces 1%) to allow laser radiation between mirrors 84 and 86 to sarily the direction depicted in FIG. 10. The basic design of exit as a beam in a controlled manner. Lamp 88 may be coherent light emitting devices (commonly known as lasers) positioned to illuminate nanoparticle layers 80 on substrate and various embodiments are described in further detail in 82. Nanoparticle layers 80 absorb the light from lamp 88 U.S. Pat. No. 5,422,907 which is incorporated herein by exciting the nanoparticles causing the nanoparticles to emit reference. light into the optical cavity where it is trapped. The trapped O155 Various uses for the nanoparticle based lasers light is then outputted as laser beam 90 from mirror 86. described herein may be envisioned by those skilled in the art. An example of a use for the nanoparticle based laser may 0151. In some embodiments, nanoparticle layers 80 may be as an optical Switch in communications arrays or in be tailored to match the emission Source. In an embodiment information processing, for example in computers. Further where the emission Source is a broadband emission Source, general information regarding the Structure and formation of there may be multiple layers of nanoparticles 80 as depicted optical switches may be found in U.S. Pat. No. 6,337,762 B1 in FIG. 9. As shown in FIG. 9 there may be four nanopar which is incorporated herein by reference. ticle layers 80. In this embodiment, where the emission Source is a low pressure gas discharge lamp (with a wide DisplayS bandwidth emission), first nanoparticle layer 80 (first layer distinguished as being closest to lamp 88) may include 0156 An extension of the application of nanoparticles in relatively Smaller sizes of the nanoparticles described light emitting devices is the use of nanoparticle based light herein. The result of using the Smaller nanoparticles being emitting devices in display devices. Display devices, Such as that their bandgap is larger thereby lowering the absorption flat panel displayS, are currently produced using liquid edge and rendering the layer more absorptive of the longer crystal technology. The current liquid crystal technology wavelength radiation. Second nanoparticle layer 80 (adja currently in use in flat panel displays are limited due to cent first nanoparticle layer 80), may include nanoparticles manufacturing expense, high power consumption, and tech of a Somewhat larger Size, with the result that the Second nical limitations Such as a relatively narrow viewing angle. layer will be more absorptive of shorter wavelength radia Organic LEDs (OLED), molecular and polymer based, are tion. Third nanoparticle layer 80 (adjacent Second nanopar also currently under consideration as a replacement for the ticle layer 80), may include nanoparticles of a Somewhat liquid crystal technology. Unfortunately, OLEDs are limited US 2003/0003300 A1 Jan. 2, 2003 by Short lifetimes and a catastrophic Sensitivity to water and Sensing Elements oxygen. OLED lifetimes decrease even more with increas ing brightness (and increasing current), which has relegated 0162 There are many possible applications for the method and/or products thereof described herein. In an them to Small display applications Such as cell phone embodiment, the nanoparticles may be used to provide SCCCS. information about a biological State or event or to detect an 0157 FIG. 6 depicts an embodiment of display 62 analyte in a fluid. Traditional methods for detecting biologi including a plurality of light emitting devices that include cal compounds in Vivo and in vitro rely on the use of nanoparticles as described herein. Display 62 may be a flat radioactive markers. These labels are effective because of panel display. Display 62 may include a Support 64. The use the high degree of Sensitivity for the detection of radioac tivity. However, many basic difficulties exist with the use of of discrete nanoparticles may allow nanoparticle based light radioisotopes. Such problems include the need for Specially emitting devices 52 to be mounted on flexible Support 64. trained perSonnel, general Safety issues when working with Flexible Support 64 may allow for the formation of a flexible radioactivity, inherently short half-lives with many com display which might be more difficult to damage and easier monly used isotopes, and disposal problems due to full to transport. The display may include Sets of different landfills and governmental regulations. As a result, current colored nanoparticle based light emitting devices 52. Nano efforts have shifted to utilizing non-radioactive methods of particle based light emitting devices 52 may function as detecting biological compounds. These methods often con described herein. The colors of the nanoparticle based light sist of the use of fluorescent molecules as tags (e.g. fluo emitting devices 52 may include any combination of colors rescein, ethidium, methyl coumarin, and rhodamine) as a capable of producing alone or in combination the colors method of detection. However, problems still exist when necessary for the envisioned application of display 62. using these fluorescent markers. Problems include pho Commonly used colors may include red, blue, and green. tobleaching, Spectral Separation, low fluorescence intensity, Short half-lives, broad spectral linewidths, and non-gaussian 0158. In another embodiment, display 62 may include asymmetric emission Spectra having long tails. one or more layers of colored transparent layers of nano particle based light emitting devices 52. The colored trans 0163 Fluorescence is the emission of light resulting from parent layers of nanoparticle based light emitting devices 52 the absorption of radiation at one wavelength (excitation) may emit light alone or in combination to achieve colors not followed by nearly immediate reradiation usually at a dif possible when individual colored layers are used. The col ferent wavelength (emission). Fluorescent dyes are fre ored transparent layers of light emitting devices 52 may emit quently used as tags in biological Systems. For example, light from a portion of light emitting devices 52 within a compounds Such as ethidium bromide, propidium iodide, particular layer or from the entire colored layer. Hoechst dyes (e.g., benzoxanthene yellow and bixbenzimide ((2-4-hydroxyphenyl-5-4-methyl-1-piperazinyl-2,5'-bi 0159 FIG. 7 depicts an embodiment of a basic design for 1H-benzimidazol) and (2-4-ethoxyphenyl-5-4-methyl-1- a flat panel display including multiple layers of transparent piperazinyl)-2,5'-bi-1H-benzimidazol)), and DAPI (4,6-dia nanoparticle based light emitting devices. Some embodi midino-2-phenylindole) interact with DNA and fluoresce to ments of display 62 may include electrical connectors that visualize DNA. Other biological components can be visu provide electrical power or Signals to the individual light alized by fluorescence using techniques Such as immunof emitting devices. The application or absence of an electrical luorescence that utilizes antibodies labeled with a fluores Signal may determined whether the light emitting devices 52 cent tag and directed at a particular cellular target. For emit light or remain in an unlighted State. example, monoclonal or polyclonal antibodies tagged with 0160 In an embodiment, a display may include an input fluorescein or rhodamine can be directed to a desired cellular to receive display information. The input may function to target and observed by fluorescence microScopy. An alter control the intensity of the light emitted by the light emitting nate method uses Secondary antibodies that are tagged with diodes. The input may function to control the color of the a fluorescent marker and directed to the primary antibodies light emitted by the display Screen by controlling which of to visualize the target. the light emitting devices are activated at a given time. The 0164. There are chemical and physical limitations to the input may control the color of the light emitted in any use of organic fluorescent dyes. One of these limitations is number of ways. In one embodiment, one or more of Several the variation of excitation wavelengths of different colored different colored light emitting devices may be signaled to dyes. As a result, Simultaneously using two or more fluo emit Simultaneously combining to appear as if a different rescent tags with different excitation wavelengths requires color, other than of the actual light emitting devices them multiple excitation light Sources. This requirement thus adds Selves is being emitted. The input means may function to to the cost and complexity of methods utilizing multiple control what portion of the light emitting devices forming fluorescent dyes. the array emit light. 0.165 Another drawback when using organic dyes is the 0.161 Some embodiments of a display may include a deterioration of fluorescence intensity upon prolonged expo transparent cover 66. Transparent cover 66 may be posi Sure to excitation light. This fading is called photobleaching tioned over at least a portion of the light emitting diodes and is dependent on the intensity of the excitation light and forming the array. Transparent cover 66 may function to the duration of the illumination. In addition, conversion of assist in protecting portions of the display from physical the dye into a nonfluorescent species is usually irreversible. damage. Transparent cover 66 may also serve additional Furthermore, the degradation products of dyes are organic functions Such as reducing glare caused by lighting, natural compounds that may interfere with biological processes or man made, not associated with the display panel itself. being examined. US 2003/0003300 A1 Jan. 2, 2003

0166 Another drawback of organic dyes is the spectral as the Solvent dielectric properties, the shape of the host overlap that exists from one dye to another. This is due in molecule, and how it complements the guest. Upon host part to the relatively wide emission Spectra of organic dyes guest association, attractive interactions occur and the mol and the Overlap of the Spectra near the tailing region. Few ecules Stick together. The most widely used analogy for this low molecular weight dyes have a combination of a large chemical interaction is that of a “lock and key.” The fit of the Stokes shift, which is defined as the separation of the key molecule (the guest) into the lock (the host) is a absorption and emission maxima, and high fluorescence molecular recognition event. output. In addition, low molecular weight dyes may be 0170 Sensing element 68, in one embodiment, is capable impractical for Some applications because they do not pro of both binding the analyte(s) of interest and creating a vide a bright enough fluorescent Signal. The ideal fluorescent detectable Signal. In one embodiment, Sensing element 68 label should fulfill many requirements. Among the desired will create an optical Signal when bound to analyte of qualities are the following: (i) high fluorescent intensity (for interest 76. In one embodiment, a detectable signal may be detection in Small quantities), (ii) a separation of at least 50 caused by the altering of the physical properties of indicator nm between the absorption and fluorescing frequencies, (iii) ligand 70 bound to receptor 72. In one embodiment, two solubility in water, (iv) ability to be readily linked to other different indicators are attached to receptor 72. When ana molecules, (v) Stability towards harsh conditions and high lyte 76 is captured by receptor 72, the physical distance temperatures, (vi) a Symmetric, nearly gaussian emission between the two indicators may be altered Such that a change lineshape for easy deconvolution of multiple colors, and in the Spectroscopic properties of the indicators is produced. (vii) compatibility with automated analysis. At present, none This process, known as Forster energy transfer, is extremely of the conventional fluorescent labels satisfies all these Sensitive to Small changes in the distance between the requirements. Furthermore, the differences in the chemical indicator molecules. In another embodiment the optical properties of Standard organic fluorescent dyes make mul Signal might be created through electron or hole donation tiple, parallel assays quite impractical Since different chemi from the nanoparticle to the analyte, or from the analyte to cal reactions may be involved for each dye used in the the nanoparticle. The analyte may quench the nanoparticle variety of applications of fluorescent labels. fluorescence. The nanoparticle may donate an electron to a 0167 Thus, there is a need for a fluorescent label that redox active Species in Solution, which quenches that nano Satisfies the above-described criteria for use in assay Sys particle fluorescence, or changes color to be detected by temS. absorbance measurements, or may itself fluorescence or 0168 FIG. 8 depicts a schematic representation of an have its fluorescence quenched. embodiment of a nanoparticle labeled analyte. Sensing ele 0171 In one embodiment, a redox enzyme is attached via ment 68 may include indicator 70, receptor 72, and linker covalent or noncovalent binding to the nanoparticle. The 74. Nanoparticles formed by any of the methods described nanoparticle Serves as a photoreceptor. When light with herein may better satisfy the above criteria than more widely Sufficient energy Shines on the particle, an excision may known traditional methods. Sensing element 68 may include form, or an excited electron, or an excited hole might form. the nanoparticles as described herein and in Some embodi The electron or the hole may be transferred to the enzyme to ments possess both the ability to bind analyte 76 of interest provide the energy necessary to drive an enzymatically and to create a signal. Sensing element 68 may include catalyzed redox reaction. The redox enzyme may be an receptor molecules 72 which posses the ability to bind NAD or NADH dependent enzyme, or an FAD or an FADH analyte 76 of interest and to create a modulated Signal. dependent enzyme. The enzyme may be Stereospecific to Alternatively, the Sensing elements may include receptor produce a desired Stereoisomer. molecules and indicators. The receptor molecule may posses 0172 In another embodiment, indicator ligand 70 may be the ability to bind to an analyte of interest. Upon binding preloaded onto the receptor 72. Analyte 76 may then dis analyte 76, receptor 72 may cause indicator 70 to produce a place indicator ligand 70 to produce a change in the Spec Signal. Receptor molecules 72 may be naturally occurring or troscopic properties of Sensing elements 68. In this case, the Synthetic receptors formed by rational design or combina initial background absorbance is relatively large and torial methods. decreases when analyte 76 is present. Indicator ligand 70, in 0169. Sensing element 68, in some embodiments, pos one embodiment, has a variety of spectroscopic properties in sesses both the ability to bind analyte 76 and to create a addition to those imparted by the nanoparticles described Signal. Upon binding analyte of interest 76, receptor mol herein which may be measured. These spectroscopic prop ecule 72 may cause indicator molecule 70 to produce the erties include, but are not limited to, ultraViolet absorption, Signal. Indicator 70 may produce a distinct Signal in addition Visible absorption, infrared absorption, fluorescence, and to the nanoparticles included in Sensing element 68. In magnetic resonance. In one embodiment, the indicator is a alternate embodiments the nanoparticles themselves may be dye having either a strong fluorescence, a strong ultraViolet use as indicator 70. Some examples of natural receptors absorption, a strong visible absorption, or a combination of include, but are not limited to, DNA, RNA, proteins, these physical properties. When indicator 70 is mixed with enzymes, oligopeptides, antigens, and antibodies. Either receptor, receptor 72 and indicator 70 interact with each natural or Synthetic receptorS may be chosen for their ability other Such that the above mentioned spectroscopic proper to bind to the analyte molecules in a specific manner. The ties of indicator 70, as well as other Spectroscopic properties forces which drive association/recognition between mol may be altered. The nature of this interaction may be a ecules include the hydrophobic effect, anion-cation attrac binding interaction, wherein indicator 70 and receptor 72 are tion, electroStatic attractions, covalent binding, Steric inter attracted to each other with a Sufficient force to allow the actions, chiral interactions, and hydrogen bonding. The newly formed receptor-indicator complex to function as a relative Strengths of these forces depend upon factorS Such single unit. The binding of indicator 70 and receptor 72 to US 2003/0003300 A1 Jan. 2, 2003

each other may take the form of a covalent bond, an ionic Linkers bond, a hydrogen bond, a van der Waals interaction, or a 0176). In some embodiments, the receptor and/or indica combination of these bonds. tors may be coupled to the nanoparticles by a linker group. 0173 For example, analytes 76 within a fluid may be A variety of linker groups may be used. The term “linker”, derivatized with a fluorescent tag before introducing the as used herein, refers to a molecule that may be used to link Stream to Sensing elements 76. AS analyte molecules are a receptor to an indicator, a receptor to a nanoparticle or adsorbed by the Sensing element, the fluorescence of the another linker, or an indicator to a nanoparticle or another Sensing element may increase. The presence of a fluorescent linker. A linker is a hetero or homobifunctional molecule that Signal may be used to determine the presence of a specific includes two reactive Sites capable of forming a covalent analyte. Additionally, the Strength of the fluorescence may linkage with a receptor, indicator, other linker or nanopar be used to determine the amount of analyte 68 within the ticle. The capping agent described herein may function as Stream. The basic design of using nanoparticles in biological the linger. Suitable linkers are well known to those of skill assays is described in further detail in U.S. Pat. No. 6,306, in the art and include, but are not limited to, Straight or 610 B1 which is incorporated herein by reference. branched-chain carbon linkers, heterocyclic carbon linkers, or peptide linkers. Particularly preferred linkers are capable Receptors of forming covalent bonds to amino groups, carboxyl groups, or Sulfhydryl groups or hydroxyl groups. Amino 0.174. A variety of natural and synthetic receptors may be binding linkers include reactive groupS. Such as carboxyl used. The Synthetic receptorS may come from a variety of groups, isocyanates, isothiocyanates, esters, haloalkyls, and classes including, but not limited to, polynucleotides (e.g., the like. Carboxyl-binding linkers are capable of forming aptamers), peptides (e.g., enzymes and antibodies), Synthetic include reactive groupS Such as various amines, hydroxyls receptors, polymeric unnatural biopolymers (e.g., polythio and the like. Sulfhydryl-binding linkers include reactive ureas, polyguanidiniums), and imprinted polymers. Natural groupS Such as Sulfhydryl groups, acrylates, isothiocyanates, based Synthetic receptors include receptors which are struc isocyanates and the like. Hydroxyl binding groups include turally similar to naturally occurring molecules. Polynucle reactive groupS. Such as carboxyl groups, isocyanates, otides are relatively small fragments of DNA which may be isothiocyanates, esters, haloalkyls, and the like. In certain derived by sequentially building the DNA sequence. Pep embodiments, an end of the linker is capable of binding to tides may be Synthesized from amino acids. Unnatural a crystalline composition formed from a Group IV metal biopolymers are chemical Structure which are based on element. The use of Some Such linkers is described in U.S. natural biopolymers, but which are built from unnatural linking units. Unnatural biopolymerS Such as polythioureas Pat. No. 6,037,137 which is incorporated herein by refer and polyguanidiniums may be Synthesized from diamines CCC. (i.e., compounds which include at least two amine functional Biological Circuitry groups). These molecules are structurally similar to natu 0177. In some embodiments, the nanoparticles may be rally occurring receptors, (e.g., peptides). Some diamines coupled to a biological entity. The biological entity may be may, in turn, be Synthesized from amino acids. The use of a cell, a nerve cell or a network of neurons. The biological amino acids as the building blocks for these compounds entity may be a skin cell, or a cell from another part of the allow a wide variety of molecular recognition units to be body. The cell may be a single cell microorganism, or a devised. For example, the twenty natural amino acids have mammalian cell. Connecting the nanoparticles to neurons, or Side chains that possess hydrophobic residues, cationic and other biological entities, may function in the same way as anionic residues, as well as hydrogen bonding groups. These described herein using receptors and/or linkers. However, Side chains may provide a good chemical match to bind a nanoparticles described herein may be capable of interacting large number of targets, from Small molecules to large electrically with cells. Nanoparticles may interact electri oligosaccharides. cally with cells to provide Stimulation. Upon light absorp 0.175. In one embodiment, a polymer particle might be tion, nanoparticles may generate local electric fields, or loaded with Superparamagnetic particles, or ferromagnetic drive redox reactions at the cell Surface, or create local pH particles, or paramagnetic particles, that respond to applied gradients, which may affect the cell metabolism or the cell magnetic fields. The Group IV nanoparticles might be physiology. The local Stimulation may induce the production attached to the magnetic polymer beads through Standard of certain chemical products within the cell. The integration chemistry. In one embodiment, the polymer particle Serves of biological Systems and microelectronics offers a com as a transporter of the Group IV nanoparticles to desired pletely new Strategy for next-generation heterojunction locations. In one embodiment, these materials might be used applications, Such as neuronal memory devices and pros for therapeutic purposes. A magnetic field may be applied to thetics that control cells directly. By using the appropriate direct the nanoparticle location within the body. In one receptor the nanoparticle may be coupled to a Specific type embodiment, the Group IV nanoparticles will serve as of cell or neuron or positioned at Specific Site on a cell. By photoreceptorS for therapeutic purposes. Light might be using linkers with very Short length Scales nanoparticles may shined on the patient and absorbed by the particles to drive be coupled to the cell within nanometers of the cell Surface. redox reactions within the body to destroy cancer cells. In These linkers may be strands of RNA, DNA, short amino another embodiment, heat might be generated locally by the acid Sequences, polypeptides, fatty acids, proteins, antibod nanoparticles upon light absorption to destroy the neighbor ies, or other Small molecules. Positioning nanoparticles ing cells. The light Source for these applications may be an within close proximity to the cell reduces the deleterious ultrafast femtosecond laser, or a cw laser. Two photon effects of cell membrane counter-ion charge Screening. The absorption may lead to the therapeutic benefits of this particles may be coated with molecules that induce the treatment. cellular uptake of the nanoparticles. In one embodiment, the US 2003/0003300 A1 Jan. 2, 2003 nanoparticles might be functionalized with a protein Such as 0.184 High loadings of nanoparticles can be achieved in transferring to enable cellular uptake. In another embodi the binder. Nanoparticles may make up greater than about 80 ment, the nanoparticles may be coated with molecular percent by weight of the cathode, and in Some embodiments receptors that direct the placement of the nanoparticles greater than about 90 percent by weight. The binder may be within the cell. Either within the cell, or adsorbed to the any of various Suitable polymerS Such as polyvinylidene Surface of the cell, optically activated nanoparticles experi fluoride, polyethylene oxide, polyethylene, polypropylene, ence electron-hole Separation the nanoparticles may produce polytetrafluoroethylene, polyacrylates and mixtures and electric fields, or the potential to drive local redox reactions, copolymers thereof. which may affect the viability of the cell, the metabolism, or metabolic products. Electric fields produced by nanopar 0185. Anode 94 of battery 92 may be constructed from a ticles may induce changes in the local cell potential, effec variety of materials that are suitable for use with lithium ion tively forming an example of biological circuitry. electrolytes. In the case of lithium batteries 92, anode 94 can include lithium metal or lithium alloy metal either in the Li Batteries form of a foil, grid or metal particles in a binder. 0.178 Lithium based batteries generally use electrolytes 0186 Lithium ion batteries use particles having a com containing lithium ions. The anodes for these batteries may position that may intercalate lithium. The particles may be include lithium metal (lithium batteries), or compositions held with a binder in the anode. Suitable intercalation that intercalate lithium (lithium ion batteries). The compo compounds include, for example, graphite, Synthetic graph Sitions that intercalate lithium, for use in the cathodes, ite, coke, mesocarbons, doped carbons, fullerenes, niobium generally are chalcogenides Such as metal oxides that can pentoxide and tin oxide, incorporate the lithium ions into their lattice. 0187 Lithium batteries may also include collectors 100 0179 FIG. 11 depicts a schematic of an embodiment of that facilitate flow of electricity from the battery. Collectors a battery based on the nanoparticles described herein. A 100 are electrically conductive and may be made of metal typical lithium battery 92 includes an anode 94, a cathode 96 Such as nickel, iron, Stainless Steel, aluminum and copper and separator 98 between anode 94 and cathode 96. A single and may be metal foil or preferably a metal grid. Collector battery may include multiple cathodes and/or anodes. Elec 100 may be on the surface of their associated electrode or trolyte can be Supplied in a variety of ways as described embedded within their associated electrode. further below. 0188 Separator 98 is an electrically insulating material 0180 Lithium has been used in reduction/oxidation reac that provides for passage of at least Some types of ions. Ionic tions in batteries because they are the lightest metal and transmission through the separator provides for electrical because they are the most electropositive metal. Metal neutrality in the different sections of the cell. Separator 98 oxides are known to incorporate lithium ions into their generally prevents electroactive compounds in cathode 96 lattice Structure through intercalation or Similar mechanisms from contacting electroactive compounds in anode 94. Such as topochemical absorption. Thus, many metal oxides 0189 Avariety of materials may be used for separator 98. may be effective as an electroactive material for a cathode in For example, separator 98 may be formed from glass fibers either a lithium or lithium ion battery. that form a porous matrix. Alternatively, SeparatorS 98 may 0181 Lithium intercalated metal oxides are formed in the be formed from polymerS Such as those Suitable for use as battery during discharge. The lithium leaves the lattice upon binders. Polymer Separators may be porous to provide for recharging, i.e., when a Voltage is applied to the cell Such ionic conduction. Alternatively, polymer Separators may be that electric current flows into the cathode due to the Solid electrolytes formed from polymerS Such as polyethyl application of an external current to the battery. Intercalation ene oxide. Solid electrolytes incorporate electrolyte into the generally is reversible, making metal oxide based lithium polymer matrix to provide for ionic conduction without the batteries Suitable for the production of Secondary batteries. need for liquid Solvent. 0182. In one embodiment, cathode 96 may include elec 0190. Electrolytes for lithium batteries or lithium ion troactive nanoparticles held together with a binder. Any of batteries may include any of a variety of lithium Salts. In the nanoparticle described herein may be used in cathode 96 Some embodiments, lithium Salts have inert anions and are for lithium battery 92. For example, metal oxide nanopar nontoxic. Suitable lithium salts include, but are not limited ticles produced using the methods described herein may be to, lithium hexafluorophosphate, lithium hexafluoroarsenate, held together with a binder to produce cathode 96. Nano lithium bis(trifluoromethyl sulfonyl imide), lithium trifluo particles for use in cathode 96 generally may have any romethane Sulfonate, lithium tris(trifluoromethyl sulfonyl) shape, e.g., roughly Spherical nanoparticles or elongated methide, lithium tetrafluoroborate, lithium perchlorate, nanoparticles. Cathode 96 may include a mixture of different lithium tetrachloroaluminate, lithium chloride and lithium types of nanoparticles (e.g., Vanadium oxide and titanium perfluorobutane. oxide nanoparticles). 0191) If a liquid solvent is used to dissolve the electro 0183 Cathode 96 optionally may include electrically lyte, the Solvent may be inert and may not dissolve the conductive particles in addition to the electroactive nano electroactive materials. Generally appropriate Solvents particles. These Supplementary, electrically conductive par include, but are not limited to, propylene carbonate, dim ticles generally are also held by the binder. Suitable elec ethyl carbonate, diethyl carbonate, 2-methyl tetrahydrofu trically conductive particles include conductive carbon ran, dioxolane, tetrahydrofuran, 1, 2-dimethoxyethane, eth particles Such as carbon black, metal particles Such as Silver ylene carbonate, gamma.-butyrolactone, dimethyl particles and the like. These particles may also be nanopar Sulfoxide, acetonitrile, formamide, dimethylformamide and ticles, produced by any of the methods described herein. nitromethane. US 2003/0003300 A1 Jan. 2, 2003

0.192 The shape of the battery components may be 0198 A typical preparation begins inside a glovebox. adjusted to be suitable for the desired final product, for Diphenylsilane solution (250-500 mM in octanol) is loaded example, a coin battery, a rectangular construction or a into an inconnell high-pressure cell (0.2 mL) and Sealed cylindrical battery. The battery generally includes a casing under a nitrogen atmosphere. After removing the cell from with appropriate portions in electrical contact with current the glovebox, it is attached via a three-way valve to a collectors and/or electrodes of the battery. If a liquid elec stainless steel high-pressure tube (~40 cm) equipped with a trolyte is used, the casing inhibits the leakage of the elec Stainless Steel piston. Deionized water is pumped into the trolyte. The casing may help to maintain the battery ele back of the piston with an HPLC pump (Thermoquest) to ments in close proximity to each other to reduce resistance inject oxygen-free octanol through an inlet heat eXchanger within the battery. A plurality of battery cells may be placed and into the reaction cell to the desired pressure, between in a single case with the cells connected either in Series or 140 and 345 bar. The cell is covered with heating tape (2 ft) in parallel. Further general information regarding the Struc and heated to 500° C. (+0.2°C.) within 15-20 min with use ture and formation of lithium batteries may be found in U.S. of a platinum resistance thermometer and a temperature Pat. No. 6,130,007 which is incorporated herein by refer controller. The reaction proceeds at these conditions for 2 h. CCC. Chloroform is used to extract the Si nanoparticles from the cell upon cooling and depressurization. The nanoparticle EXAMPLES dispersion is Subsequently dried and the organic-Stabilized Si nanoparticles are redispersed in hexane or chloroform. 0193 The following examples are included to demon The small 15 A diameter particles also redisperse in ethanol. Strate certain embodiments. It should be appreciated by The larger Si nanoparticles, with slightly broader Size dis those of skill in the art that the techniques disclosed in the tributions, are produced by increasing the Si:octanol mole examples which follow represent techniques discovered ratio with hexane as a Solvent; a typical Si:octanol mole ratio which function well in the practice of the disclosure herein. is 1000:1. The reaction yield in percent conversion of Si However, those of skill in the art should, in light of the precursor to Si incorporated in the nanoparticles varies from present disclosure, appreciate that many changes can be O.5% to 5%. made in the Specific embodiments which are disclosed and still obtain a like or similar result without departing from the 0199. In another experiment Si nanoparticles were syn Spirit and Scope of the invention. thesized via thermal degradation of a Silicon precursor in Supercritical hexane. 1.5 mL of a Stock Siprecursor Solution 0194 The following non-limiting examples demonstrate (250 mM diphenylsilane and 25 mM octanethiol in hexane) that by using a Si Surface-passivating Solvent heated and was loaded into a 10 mL cylindrical titanium reactor in a pressurized, the necessary temperatures can be reached to nitrogen glove box. All chemicals used for the Synthesis degrade the Si precursor while maintaining Solvation of the were degassed to remove oxygen and Stored in a nitrogen capping ligand to arrest particle growth. A temperature of rich environment. The titanium reactor was Sealed, removed 500 C. promotes Si crystallization. In certain embodiments from the glove box, wrapped with high temperature heating a Supercritical (Sc) Solvent can be used to provide a Solvent tape and heated to 500 C. The reaction proceeded at 500 with a high diffusion coefficient, on the order of 10 to 10" C. and 83 bar for 30 minutes. The reactor was then allowed cms', for rapid reactant diffusion. Supercritical solvents to cool to room temperature over the course of approxi may be used in preparation of narrow particle size distribu mately 2.5 hours. The product was extracted with chloro tions, in which the particle growth is diffusion-limited. form and precipitated in exceSS ethanol to remove reaction Using the methods of the invention highly stable Si nano byproducts. The nanoparticles could be redispersed in a particles ranging from approximately 10 to 200 A in diam variey of organic Solvents for further manipulation for later eter can be produced. analysis. 0195 Material and Methods 0200. A JEOL 2010 transmission electron microscope with 17 A point-to-point resolution operating with a 200 kV 0196) Diphenylsilane and anhydrous 1-octanol and hex accelerating Voltage with a GATAN digital photography ane, packaged under nitrogen, were obtained from Aldrich System was used for transmission electron microScopy. In Chemical Co. (St. Louis, Mo.) and stored in a nitrogen Situ elemental analysis was performed on the nanoparticles glovebox. with an Oxford energy dispersive spectrometer. Electron 0.197 Organic-passivated Sinanoparticles were prepared diffraction images were obtained with the JEOL 2010 oper by thermally degrading diphenylsilane in mixtures of ating at 200 kV. Absorbance spectra were recorded with a octanol and hexane (octanol:T=385 C.P=34.5 bar, hex Varian Cary 500 UV-Vis-NIR spectrophotometer with Si ane: T.=235 C., P=30 bar) well above the critical point at nanoparticles dispersed in ethanol or hexane. The extinction 500 C. and 345 bar in an inconnell high-pressure cell. The coefficients, e, were determined for the nanoparticles from presence of Si particles was observed by the formation of a the relationship between the measured absorbance (A=ecl), yellow Solution; no color change was observed in the the path length (l=10 cm), and the Si concentration deter absence of diphenylsilane. When diphenylsilane was mined from dry weights. The quantity ec is the absorption degraded in the presence of Sc-ethanol rather than Sc coefficient, C. Luminescence measurements were performed octanol, the Solution quickly turned from orange to brown with a SpeX Fluorolog-3 spectrophotometer. The PL and and then clear as polydisperse micron-sized Si particles PLE Spectra were corrected with quinine Sulfate as a stan formed and settled on the walls of the reaction vessel. This dard. Quantum yields were calculated by comparison with result Suggests that, unlike ethanol, the bound octanol chains 9,10-diphenylanthracene. FTIR measurements were provide Sufficient Steric Stabilization to prevent aggregation. obtained with a Perkin-Elmer Spectrum 2000 FTIR spec The Sc-octanol quenches the reaction and passivates the Si trometer. FTIR spectra were acquired from dried films of nanoparticle Surface. Silicon nanoparticles deposited on Zinc Selenide windowS. US 2003/0003300 A1 Jan. 2, 2003 20

Example 1 0206 FIG. 12 illustrates an example of energy-disper Sive X-ray spectroscopy (EDS) analysis of an exemplary Transmission Electron Microscopy nanoparticle composition. The EDS data of the exemplary nanoparticle. The copper (Cu) peak results from the copper 0201 ATEM image of an organic-monolayer stabilized TEM grid used as a Support. Other peaks shown are the 40 A diameter Si nanoparticle exhibits a crystalline core carbon (C), oxygen (O) and Silicon (Si) peak with a well-defined faceted Surface. The lattice spacing was 3.1 A, characteristic of the distance separating the (111) Example 4 planes in diamond-like Si. Si nanoparticle may propagate through a radical mechanism as shown: X-ray Photoelectron Spectroscopy (Ph).SiH,->(Ph).SiH.= (Equation 1) 0207 X-ray photoelectron spectroscopy (XPS), however, provides an elemental analysis of the particles which gives an indication of how the nanoparticles are capped with the 0202) The benzene rings may help stabilize the diphe organic ligands. XPS data for 15 A diameter Si nanopar nylsilane radical intermediates by delocalizing the electron ticles, which reveals that the Sample contains a Si:C ratio of charge. These free radicals can react to form Si-Si bonds. O.70:1. The octanol molecules Subsequently displace the phenyl groupS and cap the Si particle Surface. There are other (0208) By using a shell approximation, d=a. (3.Nf4t), possible mechanisms that include the formation and degra where at is the lattice constant (5.43 A), the number of Si dation of other intermediate products, Such as triphenyl and atoms, Ni, in a nanoparticle can be calculated. Particles with tetraphenyl Silane. Furthermore, this reaction may not pro 15 A diameter (d) have approximately 88 atoms. The Si:C ceed through a free radical mechanism. ratio determined from XPS can be used to calculate approxi mately the area occupied on the nanoparticle Surface by each Example 2 capping ligand. With the Si:C ratio equal to 0.7, the 15 A cluster with 88 core Si atoms has 125 C atoms surrounding it. Each ligand has 8 carbons. Therefore, each particle is Extraction of Silicon Nanoparticles Surrounded by approximately 16 capping ligands. Dividing 0203 Size-monodisperse 15 A diameter Si nanoparticles the particle surface area by 156 indicates that each ligand were obtained by reacting diphenylsilane in pure octanol occupies an average of 44 A. This value is about twice that with Subsequent redispersion in ethanol. A fraction of the expected for a close-packed monolayer of ligands Surround Sample is made up of larger Si nanoparticles that form ing the nanoparticles. Therefore, XPS indicates that the during the reaction that do not resuspend in ethanol due to ligands coat the nanoparticles with approximately 50% their hydrophobicity, whereas the extreme surface curvature Surface coverage. An estimate of the Surface coverage of the of the 15 A diameter nanoparticles provides ethanol with largest 20 A diameter nanoparticles in the Sample size “access to the polar Si-O-C capping layer termination to distribution gives an area per molecule of 33 A, for enable the size-Selective dispersion of 15 A diameter Si approximately 70% surface coverage. FIG. 13 A and FIG. nanoparticles. The 15 A diameter nanoparticles are barely 13 B illustrate examples of X-ray Photoelectron spectros perceptible in TEM images obtained with Samples dispersed copy (XPS) analysis of an exemplary nanoparticle compo on a carbon-coated TEM grid. Low-resolution images of sition. In particular, XPS of an exemplary 15 A diameter aggregates of these 15 A diameter nanoparticles show that Silicon nanoparticles deposited on a graphite Substrate. (A) the Samples contain little Size variation. For comparison, Si2p region in the spectrum (modified area is 592.2 counts) TEM images of larger Si nanoparticles with diameters and (B) Carbon 1s region (single line) and its deconvoluted ranging from 25 to 35 A produced by performing the peaks from the graphite Substrate (dashed line) and the Synthesis in Sc-hexane with increased Si:Octanol mole ratioS capping ligand (dotted and dashed line). The modified area clearly reveal highly crystalline cores and faceted Surfaces. of the C 1S curve due to the capping ligand is 850.5 counts. Crystalline lattice planes are observed in nanoparticles as The silicon-to-carbon ratio (SiC) for this particular example small as 25 A. Electron diffraction from these nanoparticles is 0.70:1. also confirmed that the nanoparticles consist of crystalline Si cores with diamond lattice Structure. Example 5 0204. A variety of other techniques were used to charac Fourier Transformed Infra-Red Spectroscopy terize the Si nanoparticles, including, Fourier transform infrared spectroscopy (FTIR), UV-vis absorbance, and PL 0209 FTIR spectra show that the nanoparticles are most and PLE Spectroscopy. likely terminated with a combination of hydrogen and hydrocarbon chains, bound through an alkoxide (Si-O-C) Example 3 linkage. Four characteristic methylene and terminal methyl stretching modes v,co-2928 cm, v,(c)-2855 cm', In Situ Energy-Dispersive X-ray SpectroScopy v(CHip)=2954.5 cm, v, (CHFR)=2871 cm, reveal that a hydrocarbon Steric layer has indeed adsorbed to the 0205. In situ energy-dispersive X-ray spectroscopy particle surface. The notable absence of the hydroxyl stretch (EDS) measurements of the nanoparticles imaged by TEM (vo =3300 cm) and the presence of the strong doublet revealed Si in high abundance with the presence of oxygen corresponding to the Si-O-CH2- Stretching modes, and carbon as well. A quantitative analysis of the elemental vs. o ch2 =1100-1070 cm', Suggests covalent alkox ratioS was not possible Since the Supporting Substrate was ide bonding to the Si nanoparticle Surface. Siloxane carbon containing a measurable amount of residual oxygen. Si-O-Si stretches typically occur at slightly lower wave US 2003/0003300 A1 Jan. 2, 2003 number (1085 and 1020 cm); however, the presence of 0212. The Si nanoparticle PL was remarkably stable in residual oxide on the nanoparticle Surfaces cannot be com the presence of atmospheric oxygen, especially when con pletely excluded based on these data alone. The absence of sidering the Sensitivity of the optical properties of porous-Si the very Strong characteristic aryl-Si Stretching mode, at to Surface chemistry, Such as Oxidation. The Sc-technique vs. p-1125-1090 cm', confirms precursor degradation. provides Si nanoparticles with sufficiently robust surface The lack of the strong vs. st-1080–1040 cm stretch passivation to prevent Strong interactions between the Si ing mode eliminates the possibility that the Nanoparticles cores and the Surrounding Solvent to enable efficient lumi consist of a Si-C core, or that the alkane layer is directly nescence from Si. Comparison between the PL and PLE adsorbed to the Sisurface. Strong Si TO (transverse optical) spectra reveals a Stokes shift of approximately 100 meV phonon bands occur between 450 and 520 cm, indicating with respect to the lowest energy peak in the PLE spectra. that the particles are composed of Si only. Strong peaks The relatively broad PL peak has a characteristic lifetime of between 750 and 850 cm'can possibly be assigned to a 2 ns, indicating that various nonradiative processes are variety of Si-H stretching modes. There is also a possible important in the nanoparticles. It is worth noting that the carbonyl stretch at v 1700 cm'that could result from low-energy PL peak observed by Brus et al. for ~20 A octanol adsorption through a Si-C=O linkage if alcohol diameter oxide-coated Si nanoparticles at 1.6 eV was not oxidation to the aldehyde occurs. On the basis of XPS and observed in any of these samples. FTIR data, the nanoparticle surface is coated mostly by the 0213 FIG. 15 illustrates an example of photolumines hydrocarbon ligands. However, the remaining 30% to 50% cence (PL) and photoluminescence excitation (PLE) spectral of the Surface is coated with a combination of hydrogen, analysis of exemplary nanoparticle compositions. Room Si-C=O, and possibly a small portion of oxide. temperature PL are depicted as Solid lines with the excitation 0210 FIG. 14 illustrates an example of Fourier trans energy marked by a Solid arrow and PLE are depicted as formed infrared spectroscopy (FTIR) analysis of an exem dashed lines with the detection energy marked by dashed plary nanoparticle composition. The spectrum reveals that arrows. The Spectra of exemplary 15 A nanoparticles are the Sterically Stabilizing hydrocarbon chains are covalently compared with Spectra of Slightly larger particles with a linked to the Si Surface through alkoxide linkages. These broader size distribution. covalent linkages give rise to highly stable optical properties 0214 FIG. 16 illustrates an example of an absorbance in the presence of ambient oxygen and water. profile of exemplary nanoparticle compositions. The absor Example 6 bance spectra were insensitive to Solvent polarity, indicating Optical Properties that the absorbance is due to an excision State and not a charge-transfer transition between bound ligands. Mote the 0211 The Si nanoparticles photoluminesce with overall blue shift in the absorbance edge, and the appearance of quantum yields as high as 23% at room temperature. Several discrete optical transitions in the spectra of exemplary 15 A closely spaced discrete features appear in the PLE Spectra of nanoparticles compared to the larger, more polydisperse the 15 A diameter nanoparticles, which are mirrored by a nanoparticles. few meV in the absorbance Spectra. The nanoparticles exhibit size-dependent PL and PLE spectra, with the smaller 0215 FIG. 17 illustrates a comparison between the nanoparticles (approximately 15 A diameter) emitting in the extinction coefficients of bulk Silicon as compared to the near-UV and the larger nanoparticles (approximately 25 to extinction coefficient of an exemplary nanoparticle compo 40 A diameter) emitting green light. For all sizes, the Sition. The absorption edge corresponds to the indirect T to absorption coefficient a was found to increase quadratically X transition and the two peaks in the bulk Si Spectra with incident energy, C-hv-Elf, near the absorption edge, correspond to the T to T and L to L critical points at 3.4 and which is characteristic of a predominantly indirect transi 4.3 eV, respectively. Note the apparent blue shift of the T to tion. Comparison of the extinction coefficients for bulk Si X and L to L transitions in the nanoparticles due to quantum with those measured for the 15 A diameter nanoparticles. confinement and the apparent red shift of the T to T The indirect T->X transition remains the lowest energy transition, as predicted by Ramakrishna and Friesner, 1992. transition, increasing from 1.2 eV (bulk Si) to 1.9 eV due to 0216 FIG. 21 illustrates four single dot PL spectra of quantum confinement. It should be noted that it appears that four different nanoparticles at room temperature, showing the direct T->T transition has red shifted to 3.2 eV from 3.4 the narrow line widths. The peak widths are very sharp eV and the L->L transition energy has blue-shifted from 4.4 compared to previously studied nanocrystalline Silicon. eV to 4.7 eV, in quantitative agreement with empirical Inset: Mean spectral trajectory of a Single particle showing pseudopotential calculations by Ramakrishna and Friesner, although these assignments cannot be made conclusively. that spectral diffusion is not observable within the experi Further comparison of the extinction coefficients measured mental accuracy of the instrumentation. for the nanoparticles with values for bulk Si reveals an 0217. The origin of the photoluminescence in Si nano overall lifting of the critical point degeneracies (direct particles is quite complex and remains actively debated. The transitions at k=0 and away from k=0), as predicted by both PL spectrum is clearly size dependent, with the larger empirical pseudopotential and tight-binding calculations, particles emitting lower energy light than the Smaller par and an oscillator Strength enhancement. These results con ticles, consistent with the general perception of quantum trast the Spectra for slightly larger, more polydisperse Si confinement effects in Si. The PL from Si nanoparticles, nanoparticles, ranging in size from 25 to 40 Ain diameter, however, has been shown to be highly Sensitive to Surface which exhibit monotonically increasing featureleSS absor chemistry, especially the presence of oxide on the nanopar bance spectra. A Slight excision peak, however, does seem to ticle surface. Indeed, the PL spectrum of the 15 A diameter appear in the PLE Spectra for the larger nanoparticles at 2.6 nanoparticles is complicated by the presence of two promi eV (470 nm). nent peaks in the 15 A nanoparticle spectrum: one at 2.95 eV US 2003/0003300 A1 Jan. 2, 2003 22

(419 nm) and one at 2.65 eV (467 nm). Furthermore, the PL 0220 AS has been found for many single molecule sys was found to depend on the excitation wavelength, with 3.4 tems, and other nanoparticles such as CdSe and InP, the Si eV (363 nm) excitation yielding the highest quantum yield nanoparticles exhibit fluorescence intermittency, or “blink and the sharpest PL. Increasing the excitation energy from ing', with a Stochastic Switching on and off of the PL signal. 3.4 eV to 4.4 eV (281 nm) led to a decrease in the intensity Although the mechanism for blinking in nanoparticles is not of the highest energy feature with respect to the low-energy known, the “on” State can be viewed as an optically coupled “Satellite' peak, and a decrease in the Overall quantum yield. ground and excited State, whereas the “off State is anopti Although the peaks cannot be assigned conclusively at this cally “dark” state. The emission from a cluster of particles time, it can be proposed that the higher energy peak is exhibited intensity blinking against a gradually decaying intrinsic to quantum confinement in Si nanoparticles and the background signal as shown in FIG. 26. One obvious test lower energy peak results from the presence of oxygen on therefore involved the inspection of the time-resolved spec the particle Surface. Calculation of the PL energy due to tra for a gradually decaying background Signal. In cases with intrinsic quantum confinement in Si can in Some cases differ few particles, a decaying background did not appear; how from the PL energy due to surface states, specifically Si=O. ever, the blinking behavior exhibited multiple intensity For nanoparticles greater than 3 nm in diameter, the intrinsic Steps. In the Single particle case, the blinking Spectra clearly and Surface State emission energies are the same, with exhibited monotonic time-dependent PL intensities. AS a emission at 2 eV (620 nm). However, 15 A diameter Secondary indicator, the PL peak energy fluctuation was nanoparticles were predicted to give rise to intrinsic PL at examined. When multiple particles produced the emission, 2.8 eV, and Surface state PL resulting from the presence of the Spectra fluctuated in energy as different sized particles oxygen at 2.3 eV (537 nm). The PL spectra of the Si blinked on and off. Therefore, the blinking behavior and nanoparticles are consistent with this interpretation. It peak fluctuation were used to rigorously determine if the should be noted, however, that peak Splitting due to Separate measured spectra were truly a result of individual nanopar direct and phonon-assisted absorption and emission events ticles (See FIG. 27 through FIG. 29). has been observed for porous Si and may provide an 0221) The spectral line widths of the single Si dot PL alternative explanation. were as narrow as 150 meV. Although three times broader Example 7 than the room temperature line widths measured for Single CdSe nanoparticles, these linewidths represent the narrowest Single Dot Spectroscopy Methods measured to date for Si nanostructures. The four peaks 0218. Single dot spectroscopy measurements were con shown in FIG. 21 represent typical narrow spectra measured ducted using a confocal optical microScope in an epi from Octanethiol capped Si nanoparticles. Spectra deter illumination configuration. Samples consist of Si nanopar mined to originate from individual nanoparticles did not ticles dispersed on a glass coverslip by Spin coating very show measurable spectacle diffusion (FIG. 21 inset), Sug dilute nanoparticle Suspension in chloroform. The excitation gesting that these organic-capped Si nanoparticles are stable laser beam from an Ar+ laser was focused by an oil against degradation in air. With excitation at 488 nm, the immersion objective (1.2 NA) to a diffraction-limited spot emission peak maxima shift through the visible, from ~525 on the Sample coverSlip. A computer-controlled piezo Stage nm up to ~700 nm. Due to experimental constraints, exci Scans the Sample. The Sample photoluminescence was col tation wavelengths shorter than 488 nm were not accessible, lected through the same objective, filtered with a holo however, the ensemble spectra clearly show that blue emis graphic notch filter to remove residual excitation light, and Sion results from particles on the Small end of the size detected by an avalanche photodiode (APD). Alternatively, distribution. Silicon can be made to emit visible light across the emission spectra are obtained by directing the light all frequencies in the visible spectrum by tuning the particle output to a polychromator equipped with an intensified size. This is rather remarkable, given that the bulk band gap charged-coupled device (ICCD) to record the intensity as a of Si is in the near-IR at 1.1 eV. function of wavelength. 0222. In order to gain a better understanding of the nature 0219. In order to obtain PL spectra from individual Si of the light emitting State in these organic-monolayer pas nanoparticles with a range of sizes in a single experiment, Sivated nanoparticles, PL lifetimes were measured and the octanethiol-coated Si nanoparticles were Synthesized with a radiative rate was determined. 17 Microsecond scale PL broad size distribution, having an average diameter of lifetime, observed previously in por-Si and oxide capped Si 4.65+1.36 nm as determined by TEM (based on 361 dots) nanoparticles, was not detected in our Sample. Instead, it is and 4.35+2.02 mm determined by AFM height profiles of estimated that 98.2% of the total PL exhibit a lifetime of the sample (FIG. 24). The PL spectra obtained from the less than or equal to 20 ns. FIG. 27 shows the time-resolved nanoparticles dispersed in chloroform were correspondingly decay of the PL of the Si nanoparticles dispersed in chlo broad. For example, the PL peak shown in FIG. 25 shifts as roform. It was necessary to implement three exponentials to a function of excitation wavelength largely due to the broad fit the data: I(t)=Ae"+Ae"+Ase", where I(t) is the Size distribution of the Sample. At longer excitation wave measured PL intensity as a function of time, t, after the lengths, only the larger nanoparticles with lower HOMO excitation pulse. Table I (See FIG. 30) lists the fitted LUMO energies are excited and the emission peak Shifts to constants, A1, A2, A, t, t2, ts, as a function of detection longer wavelengths. The absorbance Spectra and the photo wavelength. The octanethiol-capped Si nanoparticles exam luminescence excitation (PLE) spectra are featureless, due ined here exhibit characteristic lifetimes with a fast compo in part to the indirect nature of the Siband gap, but primarily nent (~100 ps), and two slow components with lifetimes due to the broad size distribution of the nanoparticles. At the ranging from 2 to 6 ns-at least three orders of magnitude Single particle level, however, the PL spectra is narrow, faster than those previously found for por-Si and Si nano exhibiting peaks with FWHM of 1596+/-502 cm'(-200 particles. Although the lifetimes of por-Si are characteristi meV) (See FIG. 21). cally orders of magnitude Shorter than those of bulk Si-giv US 2003/0003300 A1 Jan. 2, 2003 ing rise to relatively efficient PL-they are nonetheless aqueous Solution using mercaptoacetic acid as the colloidal characteristic of an indirect bandgap transition. Stabilizer. All chemicals were used as obtained from Sigma Chemical Co. (St. Louis, Mo.). Nanoparticles were prepared 0223 FIG. 28 depicts an example of an observation of from a stirred solution of 0.036 g CdCl2 (1 mM) in 40 mL “molecular” (-) and “continuum' (-) like Single nanoc of pure water. The pH was lowered to 2 with mercaptoacetic rystal spectra. Average of 37 molecular type spectra and 31 acid, and then raised to 7 with concentrated NaOH. Then, 40 continuum type spectra from Single nanoparticles excited at mL of 5 mM Na-S 9H2O (0.023 g) was added to the 488 nm. Each spectra was shifted So that its maximum was mixture. The solution turned yellow shortly after sulfide at Zero before averaging. Histogram insets of Spectral addition due to CdS nanoparticle formation. For peptide maxima (2) of continuum type and molecular type spec coated dots, peptide (0.041 mg/mL final Solution) was added tra, respectively. to the solution until dissolved in the initial step (with the 0224 FIG. 29 depicts an example of a comparison of the CdCl2). Additional peptide densities were not tested, but will measured ensemble spectra (-) to the reconstructed be the focus of future Studies aimed at improving binding ensemble spectra. reconstructed from the Single dot Spectra between the cell and the qdots. (-) of 68 individual Silicon nanoparticles. As a last check 0228 CdS Morbidity Studies: SK-N-SH neuroblastoma to ensure that the Single nanocrystal spectra presented in this cells (American Type Culture Collection #HTB-11) were Study indeed represent the ensemble, the PL spectrum was incubated with CdS dots at concentrations of 3x10', reconstructed from the histogram of PL peak intensity and 1.5x10', and 0.75x10' M in Dulbecco's minimum position of individual nanoparticles. The ensemble spectra essential medium (DMEM) cell culture medium (Sigma). appear very Similar to the reconstructed Spectra, as shown in These concentrations reflect multiples of the relative number FIG. 29. of qdots added to the cells in the attachment procedure, up Example 8 to ten times in excess. After adjustment to biocompatible Salt concentrations (9 g/L), cell death did not occur with CdS dot Fluorescence Decay and Fluorescence Quantum addition. Cells were studied for five days for proliferation Yield Measurements and attachment. No differences from controls were observed. 0225. Fluorescence decays were obtained by time-corre lated single photon counting (TCSPC) with 488-nm with 0229 Conjugation of Quantum Dots to IgG Antibody: vertically polarized excitation pulses (At.-200 fs, repetition Goat IgG antibody (Jackson Immunochemistry) was rate 3.8 MHz) from a mode-locked Ti:sapphire laser system covalently linked to CdS qdots at the carboxyl terminus of (Coherent Mira 900, Coherent Pulse Picker Model 9200, the dot capping ligands. Antibody was added to MES Inrad SHG/THG model 5-050). Emission was collected at (2-(N-morpholino) ethanesulfonic acid, Sigma) 50 mM 90 with respect to the incident excitation axis through a buffer at a concentration of 0.3 mg/mL. Then, an equal Glan-Taylor polarizer Set at the magic angle of 54.7. Long volume of 1.2 uM (80 mL batch diluted to 480 mL) qdots was added to the Solution. After a 15 min incubation period, pass filters and/or narrow band interference filters were used EDAC (1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide to block Scattered laser light. Detection electronics included hydrochloride, Sigma) was added at 4 mg/mL. Next, the pH a microchannel plate detector (Hamamatsu R3809U-50), was adjusted to pH6.5+0.2. Following 2 h in an orbital constant fraction discriminators (Tennelec TC454), time-to Shaker, the reaction was quenched using glycine at 7.5 amplitude converter (Tennelec TC864), and multichannel mg/mL. Conjugated qdots were isolated via repeated cen analyzer (Ortec TRUMP MCB). The emission wavelength trifugation (3000 g) and stored in phosphate buffered saline was Selected using 10 nm-width bandpass filters. The emis (PBS) at pH7.4. Control experiments exposing qdots to Sion decay curves were evaluated by an iterative nonlinear antibody without EDAC revealed noticeable physisorption least Squares fitting procedure. The decay data was fit to a of IgG on qdots, as evidenced by pellet formation during Sum of exponential decays convoluted with the instrument centrifugation. However, absorbance measurements of these response (-50 ps FWHM). The quality of the fit was nanoparticles revealed Substantially leSS IgG binding than in evaluated by the reduced X. the presence of EDAC. Raising the pH above 6.5, the 0226. The fluorescence quantum yield of Sinanoparticles physisorbed antibody dissociated from the nanoparticles. dispersed in chloroform was measured relative to Therefore, prior to all nerve cell labeling experiments, the Rhodamine 6G in ethanol (QY=95%) using 488 nm exci nanoparticles were transferred to 1 mL of PBS (pH 7.4). As tation on a fluorometer (SPEX) in a right-angle geometry. a result of the crosslinking chemistry in the dotitantibody The absorbance of both Si Suspension and R6G solution at conjugation Step, Some agglomeration of particles occurred; 488 nm were adjusted to ~0.06. The fluorescence spectra however, the aggregates were Small enough to remain Sus were corrected for detector response. pended in Solution. Example 9 0230 Attachment of Quantum Dot-Complexes to Cells: Qdot-complexes were attached to cells using Standard Formation of Sensing Elements/Analyte Complexes immunocytology techniques M. C. Willingham, in Methods in Molecular Biology, Vol. 115, Immunocytochemical Meth 0227 Synthesis of CdS Quantum Dots (and Peptide ods and Protocols (Ed: L. C. Javois), Humana Press, Totowa, Coated CdS Dots): Dots were synthesized using previously N.J. 1999, Ch. 16.). Briefly, cells were placed on 22x22 mm published methods H. M. Chen, X. F. Huang, L. Xu, J. Xu, no. 1 thickness coverslips using imaging chambers (Sigma) K. J. Chen, D. Feng, Superlattices Microstruct. 2000, 27, 1.). to retain fluid. Cells were cultured in DMEM media (Sigma) Briefly, carboxyl-stabilized CdS nanoparticles were synthe at 37 C. and 5% CO in sterile conditions. After the cells sized by arrested precipitation at room temperature in an attained -70% confluency, cells were washed with 10 mM US 2003/0003300 A1 Jan. 2, 2003 24

PBS (pH 7.4) five times. Then, the cells were blocked with ticles, unreacted precursor was removed by extraction with 5% bovine serum albumin (BSA) in PBS (BSA+PBS) for 30 water. The nanoparticles were filtered (Fisher, qualitative min at 4 C. Following blocking, cells were washed five P5) to remove large agglomerates of uncapped nanoparticles times in PBS. For antibody attachment, primary antibody and dried using a rotary evaporator (Buchi). The nanopar was added at 10 lg/mL in BSA+PBS and incubated for 30 ticles redisperse in either deionized water (uncapped par min at 4 C. Cells were then washed five times with PBS. ticles) or chloroform (organic capped particles). Then, antibody-qdot conjugate was added to cells to fill the 0235 Phase Behavior of Supercritical Water and 1-Hex imaging chamber (~0.25 mL/chamber). Cells were incu anethiol: The water and 1-hexanethiol phase equilibria were bated for 30 min at 4 C. then washed with PBS five times. Studied in a titanium grade 2 optical cell equipped with For peptide attachment, the imaging chamber was filled with Sapphire windows. Under the reaction conditions of 400 C. peptide-tddot conjugate Solution (~0.25 mL/chamber) taken and ~413 bar (50 uL of 1-hexanethiol in 150 uL of water), from the 80 mL batch described above. Cells were incubated water and 1-hexanethiol are miscible. This miscibility is for 30 min at 4 C., then washed five times with PBS. consistent with the phase diagram for n-alkanes in water Following Staining, cells (n-pentane and n-heptane). 0231 FIG. 18 depicts an example of room temperature 0236 Characterization Method: Gas chromatography photoluminescence (PL) () =400 nm) and photolumines (GC) measurements of hexanethiol were recorded with a cence excitation (PLE) ()=600 nm) spectra of CdS qdots Hewlett-Packard 5890A gas chromatograph. Fourier trans dispersed at pH 7.4 in PBS. form infrared (FTIR) spectroscopy measurements were per 0232 FIG. 19 depicts an example of room temperature formed using a Perkin-Elmer Spectrum 2000 spectrometer absorbance spectrum of an aqueous dispersion of CdS qdots. with the nanoparticles dispensed on PTFE cards. Lowreso The exciton peak at absorbance Spectrum of an aqueous lution transmission electron microscopy (TEM) images dispersion of CdS qdots. The exciton peak at 380 nm (3.6 were obtained on a JEOL 200CX transmission electron eV) corresponds to an average particle size of ~30 ang microScope operating with a 120-kV accelerating Voltage, StromS. while high-resolution transmission electron microScopy (HRTEM) images and selected area electron diffraction 0233 FIG. 20 depicts an example of room temperature (SAED) patterns were obtained with a Gatan digital pho absorbance spectra of CdS qdots and CdS/antibody com tography system on a JEOL 2010 transmission electron plexes. IgG absorbs at 280 nm (Squares). After binding IgG, microScope with 1.7-A point-to-point resolution operated the qdot absorbance spectrum (dashed) also exhibits this with a 200-kV accelerating Voltage. All Samples were pre feature, which is absent in bare qdots (solid). Inset: CdS pared on Electron Microscope Sciences 200-mesh carbon qdots bound to IgG (dashed) exhibit the same exciton peak coated aluminum grids by dispersing Suspended nanopar as bare qdots (solid) at 380 nm. The absorbance of antibody ticles onto the grid and evaporating the Solvent. The qdot complexes is slightly reduced due to less than 100% measured lattice Separations were indexed against Standards reaction yields. All materials were dispersed in PBS buffer for copper, CuO, and CuO. UV-visible absorbance spec (pH 7.4). troscopy was performed using a Varian Cary 300 UV-visible Spectrophotometer with the capped nanoparticles dispersed Example 10 in chloroform. X-ray photoelectron spectroscopy (XPS) was performed on a Physical Electronics XPS 5700, with a Synthesis of Organic Monolayer-Stabilized Copper monochromatic Al X-ray Source (KC. excitation at 1486.6 Nanoparticles in Supercritical Water eV). For XPS, the samples were deposited on a silicon wafer (cleaned with a 50:50 mixture of methanol/HCl), vacuum 0234 Nanoparticle Synthesis: Copper(II) nitrate hemi dried at 25 C. to remove all residual solvent, and stored pentahydrate (Aldrich), copper(II) acetate monohydrate under nitrogen. (Across), and 1-hexanethiol (95%, Aldrich) were used as received without further purification. The experimental 0237 FIG. 22 depicts examples of X-ray Photoelectron apparatus consisted of a pumping System and a 78-in.-i.d., spectroscopy (XPS) of uncapped particles produced via (a) 4-in-long 316 stainless steel reaction cell (10 mL). For Cu(NO) and (b) Cu(CHCOO) and XPS scan of organi reactions without thiols, the cell was initially loaded at cally capped nanoparticles produced with (c) Cu(NO) and ambient conditions with 1.0 mL of pure water. For reactions (d) Cu(CHCOO). All scans are offset for clarity. Cu 2p with thiols, 900 till of pure water with 100 u of 1-hex core level binding energy for copper(II) at 934 eV and anethiol was used (initial water:thiol mole ratio ~70:1). The copper(0) at 932 eV. cell was sealed and heated to 400° C. and ~173 bar using 0238 FIG. 23 depicts an example of room-temperature heating tape (Barnstead/Thermolyne) and an Omega tem UV-Visible spectra of organically capped copper nanopar perature controller. The cell temperature was measured with a K-type thermocouple (Omega). A 0.02 M copper precursor ticles Synthesized via Cu(NO) and 1-hexanethiol. Solution was injected into the cell via /16-in.-i.d. StainleSS Example 11 steel tubing by an HPLC pump (Beckman model 100A) at 4 mL/min until the operating pressure reached 413 bar. The Electrogenerated Chemiluminescence from Solution reacts immediately upon entering the reactor, as Nanoparticles observed visually in a separate experiment with an optical cell. The products precipitate upon cooling the reaction. The 0239 FIG. 31 depicts a schematic experimental setup for nanoparticles were removed from the cell with either deion electrochemistry (Such as cyclic Voltammetry, differential ized water (uncapped particles) or chloroform (organic pulse voltammetry) and electrogenerated chemilumines capped particles). In the case of the thiol capped nanopar cence (ECL) of Sinanoparticles. A cylindrical Pyrex vial 1.2 US 2003/0003300 A1 Jan. 2, 2003

cm in diameter was used as electrochemical cell, where a 1 ability to Store charge in Solution, which can Subsequently or 2 mm Pt disk, Pt coil and silver wire served as working lead to light emission upon electron and/or hole transfer. (WE), counter (CE) and reference (RE) electrodes respec This quality provides electrochemically Sensitive optoelec tively. The ECL signal was recorded on the charge coupled tronic properties that may find future use in new Sensor device (CCD) camera. ECL could also be measured by a technologies. photomultiplier tube (PMT) and recorded as cyclic voltam metric ECL or ECL transients. The diagram below illustrates 0245) Further modifications and alternative embodiments the ECL process in the vicinity of the working electrode of various aspects of the invention will be apparent to those through annihilation of electrochemically produced anion skilled in the art in View of this description. Accordingly, this and cation radicals by Stepping to the reduction and oxida description is to be construed as illustrative only and is for tion potentials alternatively. the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood 0240 FIG. 32 depicts cyclic voltammograms and differ that the forms of the invention shown and described herein ential pulse Voltammograms for Several batches of Si nano are to be taken as the presently preferred embodiments. particles in 0.1M tetrahexylammonium perchlorate (THAP), Elements and materials may be substituted for those illus N,N'-dimethylformamide (DMF) solution. The nanopar trated and described herein, parts and processes may be ticles size and dispersion were (a) 2.77+0.37, (b) 2.96+0.91 reversed, and certain features of the invention may be (c) 1.74+0.67 nm. Cyclic voltammetric ECL-voltage curves utilized independently, all as would be apparent to one are plotted in (b) and (c). Dotted curves in (a) represent the skilled in the art after having the benefit of this description response of the blank Supporting electrolyte Solution. of the invention. Changes may be made in the elements 0241 FIG.33 depicts ECL transients for (a) annihilation described herein without departing from the Spirit and Scope of cation and anion radicals in 0.1 M THAP acetonitrile of the invention as described in the following claims. (MeCN) solution, (b) oxalate coreactant system with 2.5 mM tetrabutyl ammonium oxalate added to the solution of What is claimed: (a), and (c) persulfate coreactant system in 0.1 M THAP 1. A method of forming nanoparticles comprising heating DMF solution with 6 mM tetrabutylammonium persulfate a mixture of a Group IV metal organometallic precursor and added. The size of the nanoparticles is around 2-4 nm in a capping agent at a temperature wherein the precursor diameter. decomposes, and the nanoparticles are formed. 2. The method of claim 1, wherein heating the mixture 0242 FIG.34 depicts ECL spectra for (a) annihilation of comprises heating the mixture at a pressure greater than 1 cation and anion radicals by Stepping the potential between atmosphere. 2.7 and -2.1 V at 10 Hz with integration time 30 min in the 3. The method of claim 1, wherein the organometallic same Solution as FIG.33(a), (b) oxalate coreactant System, precursor is an organosilane compound. stepping the potential between 0.1 and 3V at 10 Hz; inte 4. The method of claim 1, wherein the organometallic gration time 40 min in the same solution as FIG.33(b), and precursor is an organogermanium compound. (c) perSulfate coreactant System, stepping the potential 5. The method of claim 1, wherein the organometallic between -0.5 and -2.5V at 10 Hz; integration time 10 min precursor is an alkylsilane. in the same solution as FIG.33(c). The dotted curve in (c) 6. The method of claim 1, wherein the organometallic is the ECL spectrum for the blank Solution. precursor is an arylsilane. 0243 FIG. 35 depicts (a) Schematic mechanisms for 7. The method of claim 1, wherein the organometallic ECL and photoluminescence (PL) of Siclusters. (b) PLspec precursor is tetraethylsilane or diphenylsilane. tra at different excitation energy recorded with the same 8. The method of claim 1, wherein the capping agent is solution as for FIG.33(a). The excitation wavelength from represented by the general formula: top to bottom was between 360 and 520 nm at 20 nm intervals. 0244 Sterically stabilized silicon nanoparticles are wherein X is an atom or functional group capable of chemically stable under electrochemical electron and hole binding to the Surface of the composition; and injection. Differential pulse Voltammetry reveals a large wherein R is hydrogen, an aryl group having between electrochemical gap Separating the onset of electron and 1 and 10 carbon atoms, or an alkyl group having hole injection, related to the sizedependent HOMO-LUMO between 1 and 10 carbon atoms; gap, and discrete charging events with increased electron injection due to Coulomb blockade effects. The negatively n is an integer of at least 1. and positively charged nanoparticles produced visible light 9. The method of claim 1, wherein the capping agent is an upon electron transfer between nanoparticles, or nanopar alcohol. ticles and redox active coreactants, in Solution. This is the 10. The method of claim 1, wherein the capping agent is first example of electrogenerated chemiluminescence from an amine. Semiconductor nanoparticles. The energetic difference 11. The method of claim 1, wherein the capping agent is between ECL and PL is believed to result from the greater a thiol. sensitivity of the electron and hole wave functions with 12. The method of claim 1, wherein the capping agent is Surface States during electrochemical charge transfer com an alkene. pared to optical excitation. These results reveal that nano 13. The method of claim 1, wherein the capping agent is particles of the elemental Semiconductor, Silicon, are more octanol. chemically robust than the compound Semiconductor nano 14. The method of claim 1, wherein the mixture further particles Studied to date. The Silicon nanoparticles have the comprises a Solvent. US 2003/0003300 A1 Jan. 2, 2003 26

15. The method of claim 1, wherein the mixture further 32. The nanoparticle of claim 29, wherein the Group IV comprises a Solvent, and wherein the Solvent is a hydrocar organometallic precursor is an organogermanium com bon. pound. 16. The method of claim 1, wherein the mixture further 33. The nanoparticle of claim 29, wherein the Group IV comprises a Solvent, and wherein the Solvent is an aromatic organometallic precursor is an alkylsilane. hydrocarbon. 34. The nanoparticle of claim 29, wherein the Group IV 17. The method of claim 1, wherein the mixture further organometallic precursor is an arylsilane. comprises a Solvent, and wherein the Solvent is an non 35. The nanoparticle of claim 29, wherein the Group IV aromatic hydrocarbon. organometallic precursor is tetraethylsilane or diphenylsi 18. The method of claim 1, wherein the mixture further lane. comprises a Solvent, and wherein the Solvent is cyclohexane 36. The nanoparticle of claim 29, wherein the capping or hexane. agent is represented by the general formula: 19. The method of claim 1, wherein the mixture further comprises a Solvent, and further comprising removing (R), X entrained oxygen from the Solvent prior to heating the wherein X is an atom or functional group capable of mixture. binding to the Surface of the composition; and 20. The method of claim 1, wherein heating the mixture comprises heating the organometallic precursor and the wherein R is hydrogen, an aryl group having between capping agent at a temperature equal to or greater than the 1 and 10 carbon atoms, or an alkyl group having Supercritical temperature of the capping agent. between 1 and 10 carbon atoms; 21. The method of claim 1, wherein heating the mixture n is an integer of at least 1. comprises heating the organometallic precursor and the 37. The nanoparticle of claim 29, wherein the capping capping agent at a temperature and pressure Such that the agent is an alcohol. capping agent is in a Supercritical State. 38. The nanoparticle of claim 29, wherein the capping 22. The method of claim 1, wherein the mixture further agent is an amine. comprises a Solvent, and wherein heating the mixture com 39. The nanoparticle of claim 29, wherein the capping prises heating the organometallic precursor, the capping agent is a thiol. agent, and the Solvent at a temperature equal to or greater 40. The nanoparticle of claim 29, wherein the capping than the Supercritical temperature of the Solvent. agent is an alkene. 23. The method of claim 1, wherein the mixture further 41. The nanoparticle of claim 29, wherein the capping comprises a Solvent, and wherein heating the mixture com agent is octanol. prises heating the organometallic precursor, the capping 42. The nanoparticle of claim 29, wherein the mixture agent, and the Solvent at a temperature and pressure Such further comprises a Solvent. that the Solvent is in a Supercritical State. 43. The nanoparticle of claim 29, wherein the mixture 24. The method of claim 1, further comprising removing further comprises a Solvent, and wherein the Solvent is a the formed nanoparticles from the unreacted organometallic hydrocarbon. precursor and capping agent after heating the mixture. 44. The nanoparticle of claim 29, wherein the mixture 25. The method of claim 1, further comprising extracting further comprises a Solvent, and wherein the Solvent is an the formed nanoparticles from the unreacted organometallic aromatic hydrocarbon. precursor and capping agent with a Solvent. 45. The nanoparticle of claim 29, wherein the mixture 26. The method of claim 1, further comprising: further comprises a Solvent, and wherein the Solvent is an extracting the formed nanoparticles from the unreacted non-aromatic hydrocarbon. organometallic precursor and capping agent with a first 46. The nanoparticle of claim 29, wherein the mixture further comprises a Solvent, and wherein the Solvent is Solvent; cyclohexane or hexane. adding a Second Solvent to the first Solvent to induce 47. The nanoparticle of claim 29, wherein the mixture aggregation of the nanoparticles. further comprises a solvent, and wherein the method further 27. The method of claim 1, wherein the nanoparticles comprises removing entrained oxygen from the Solvent prior have an average particle diameter of less than about 100 to heating the mixture. angStroms. 48. The nanoparticle of claim 29, wherein heating the 28. The method of claim 1, wherein the nanoparticles mixture comprises heating the organometallic precursor and have an average particle diameter distribution of between the capping agent at a temperature equal to or greater than about 1 and 100 angstroms, and further comprising Subject the Supercritical temperature of the capping agent. ing the nanoparticles to a chromatographic proceSS Such that 49. The nanoparticle of claim 29, wherein heating the particles of different sizes are Separated from each other. mixture comprises heating the organometallic precursor and 29. A nanoparticle formed by the method comprising the capping agent at a temperature and preSSure Such that the heating a mixture of a Group IV organometallic precursor capping agent is in a Supercritical State. and a capping agent at a temperature wherein the precursor 50. The nanoparticle of claim 29, wherein the mixture decomposes forming the nanoparticles. further comprises a Solvent, and wherein heating the mixture 30. The nanoparticle of claim 29, wherein heating the comprises heating the organometallic precursor, the capping mixture comprises heating the mixture at a pressure greater agent, and the Solvent at a temperature equal to or greater than 1 atmosphere. than the Supercritical temperature of the Solvent. 31. The nanoparticle of claim 29, wherein the Group IV 51. The nanoparticle of claim 29, wherein the mixture organometallic precursor is an organosilane compound. further comprises a Solvent, and wherein heating the mixture US 2003/0003300 A1 Jan. 2, 2003 27 comprises heating the organometallic precursor, the capping a capping agent in a Supercritical fluid, wherein the orga agent, and the Solvent at a temperature and pressure Such nometallic precursors decompose forming the nanoparticles. that the Solvent is in a Supercritical State. 68. The method of claim 67, wherein the organometallic 52. The nanoparticle of claim 29, wherein the method precursor is a Group II metal organometallic compound. further comprised removing the formed nanoparticles from 69. The method of claim 67, wherein the organometallic the unreacted organometallic precursor and capping agent precursor is a Group III metal organometallic compound. after heating the mixture. 70. The method of claim 67, wherein the organometallic 53. The nanoparticle of claim 29, wherein the method precursor is a Group IV metal organometallic compound. further comprises extracting the formed nanoparticles from 71. The method of claim 67, wherein the organometallic the unreacted organometallic precursor and capping agent precursor is a Group V metal organometallic compound. with a solvent. 72. The method of claim 67, wherein the organometallic 54. The nanoparticle of claim 29, wherein the method precursor is a Group VI metal organometallic compound. further comprises: 73. The method of claim 67, wherein the organometallic precursor is a metallocene. extracting the formed nanoparticles from the unreacted 74. The method of claim 67, wherein the mixture com organometallic precursor and capping agent with a first prises a Group II metal organometallic compound and a Solvent; Group VI metal organometallic compound. adding a Second Solvent to the first Solvent to induce 75. The method of claim 67, wherein the mixture com aggregation of the nanoparticles. prises a Group III metal organometallic compound and a 55. The nanoparticle of claim 29, wherein the nanopar Group V metal organometallic compound. ticle has an average particle diameter of less than about 100 76. The method of claim 67, wherein the mixture com angStroms. prises a Group IV metal organometallic compound and a 56. The nanoparticle of claim 29, wherein the nanopar Group V metal organometallic compound. ticle has an average particle diameter distribution of between 77. The method of claim 67, wherein the mixture com about 1 and 100 angstroms, and wherein the method further prises a Group IV metal organometallic compound and a comprises Subjecting the nanoparticles to a chromatographic Group III metal organometallic compound. proceSS Such that particles of different sizes are separated 78. The method of claim 67, wherein the mixture com from each other. prises a Group IV metal organometallic compound and 57. A nanoparticle comprising a Group IV metal and a further comprising a rare earth element organometallic com capping agent coupled to the Group IV metal, wherein the pound. nanoparticle has an average particle diameter of between 79. The method of claim 67, wherein the capping agent is about 1 to about 100 angstroms, and wherein the capping represented by the general formula: agent inhibits oxidation of the nanoparticle. 58. The nanoparticle of claim 57, wherein the Group IV metal comprises Silicon. wherein X is an atom or functional group capable of 59. The nanoparticle of claim 57, wherein the Group IV binding to the Surface of the composition; and metal comprises germanium. wherein R is hydrogen, an aryl group having between 60. The nanoparticle of claim 57, wherein the capping 1 and 10 carbon atoms, or an alkyl group having agent is represented by the general formula: between 1 and 10 carbon atoms; (R), X n is an integer of at least 1. 80. The method of claim 67, wherein the capping agent is wherein X is an atom or functional group capable of an alcohol. binding to the Surface of the composition; and 81. The method of claim 67, wherein the capping agent is wherein R is hydrogen, an aryl group having between an amine. 1 and 10 carbon atoms, or an alkyl group having 82. The method of claim 67, wherein the capping agent is between 1 and 10 carbon atoms; a thiol. 83. The method of claim 67, wherein the capping agent is n is an integer of at least 1. an alkene. 61. The nanoparticle of claim 57, wherein the capping 84. The method of claim 67, wherein the capping agent is agent is an alcohol. octanol. 62. The nanoparticle of claim 57, wherein the capping 85. The method of claim 67, wherein the Supercritical agent is an amine. fluid comprises the capping agent in a Supercritical State. 63. The nanoparticle of claim 57, wherein the capping 86. The method of claim 67, wherein the Supercritical agent is a thiol. fluid comprises a hydrocarbon in a Supercritical State. 64. The nanoparticle of claim 57, wherein the capping 87. The method of claim 67, wherein the Supercritical agent is an alkene. fluid comprises an aromatic hydrocarbon in a Supercritical 65. The nanoparticle of claim 57, wherein the capping State. agent is octanol. 88. The method of claim 67, wherein the Supercritical 66. The nanoparticle of claim 57, wherein the metal fluid comprises a non-aromatic hydrocarbon in a Supercriti nanoparticle emits visible light in response to an applied cal State. Current. 89. The method of claim 67, wherein the Supercritical 67. A method of forming nanoparticles comprising heat fluid comprises hexane or cyclohexane in a Supercritical ing a mixture of one or more organometallic precursors and State. US 2003/0003300 A1 Jan. 2, 2003 28

90. The method of claim 67, wherein the mixture further 108. The nanoparticle of claim 96, wherein the capping comprises a Solvent, and further comprising removing agent is represented by the general formula: entrained oxygen from the Solvent prior to heating the mixture. 91. The method of claim 67, further comprising removing wherein X is an atom or functional group capable of the formed nanoparticles from the unreacted organometallic binding to the Surface of the composition; and precursor and capping agent after heating the mixture. 92. The method of claim 67, further comprising extracting wherein R is hydrogen, an aryl group having between the formed nanoparticles from the unreacted organometallic 1 and 10 carbon atoms, or an alkyl group having precursor and capping agent with a Solvent. between 1 and 10 carbon atoms; 93. The method of claim 67, further comprising: n is an integer of at least 1. extracting the formed nanoparticles from the unreacted 109. The nanoparticle of claim 96, wherein the capping organometallic precursor and capping agent with a first agent is an alcohol. Solvent; 110. The nanoparticle of claim 96, wherein the capping agent is an amine. adding a Second Solvent to the first Solvent to induce 111. The nanoparticle of claim 96, wherein the capping aggregation of the nanoparticles. agent is a thiol. 94. The method of claim 67, wherein the nanoparticles have an average particle diameter of less than about 100 112. The nanoparticle of claim 96, wherein the capping angStroms. agent is an alkene. 95. The method of claim 67, wherein the nanoparticles 113. The nanoparticle of claim 96, wherein the capping have an average particle diameter distribution of between agent is octanol. about 1 and 100 angstroms, and further comprising Subject 114. The nanoparticle of claim 96, wherein the mixture ing the nanoparticles to a chromatographic proceSS Such that further comprises a Solvent. particles of different sizes are Separated from each other. 115. The nanoparticle of claim 96, wherein the Supercriti 96. A nanoparticle formed by the method comprising cal fluid comprises the capping agent in a Supercritical State. heating a mixture of one or more organometallic precursors 116. The nanoparticle of claim 96, wherein the Supercriti and a capping agent in a Supercritical fluid, wherein the cal fluid comprises a hydrocarbon in a Supercritical State. organometallic precursors decompose forming the nanopar 117. The nanoparticle of claim 96, wherein the Supercriti ticles. cal fluid comprises an aromatic hydrocarbon in a Supercriti 97. The nanoparticle of claim 96, wherein the organome cal State. tallic precursor is a Group II metal organometallic com 118. The nanoparticle of claim 96, wherein the Supercriti pound. cal fluid comprises a non-aromatic hydrocarbon in a Super 98. The nanoparticle of claim 96, wherein the organome critical State. tallic precursor is a Group III metal organometallic com 119. The nanoparticle of claim 96, wherein the Supercriti pound. cal fluid comprises hexane or cyclohexane in a Supercritical 99. The nanoparticle of claim 96, wherein the organome State. tallic precursor is a Group IV metal organometallic com 120. The nanoparticle of claim 96, wherein the mixture pound. further comprises a solvent, and wherein the method further 100. The nanoparticle of claim 96, wherein the organo comprises removing entrained oxygen from the Solvent prior metallic precursor is a Group V metal organometallic com to heating the mixture. pound. 121. The nanoparticle of claim 96, wherein the method 101. The nanoparticle of claim 96, wherein the organo further comprised removing the formed nanoparticles from metallic precursor is a Group VI metal organometallic the unreacted organometallic precursor and capping agent compound. after heating the mixture. 102. The nanoparticle of claim 96, wherein the organo 122. The nanoparticle of claim 96, wherein the method metallic precursor is a metallocene. further comprises extracting the formed nanoparticles from 103. The nanoparticle of claim 96, wherein the mixture the unreacted organometallic precursor and capping agent comprises a Group II metal organometallic compound and a with a solvent. Group VI metal organometallic compound. 123. The nanoparticle of claim 96, wherein the method 104. The nanoparticle of claim 96, wherein the mixture further comprises: comprises a Group III metal organometallic compound and extracting the formed nanoparticles from the unreacted a Group V metal organometallic compound. organometallic precursor and capping agent with a first 105. The nanoparticle of claim 96, wherein the mixture Solvent; comprises a Group IV metal organometallic compound and a Group V metal organometallic compound. adding a Second Solvent to the first Solvent to induce 106. The nanoparticle of claim 96, wherein the mixture aggregation of the nanoparticles. comprises a Group IV metal organometallic compound and 124. The nanoparticle of claim 96, wherein the nanopar a Group III metal organometallic compound. ticle has an average particle diameter of less than about 100 107. The nanoparticle of claim 96, wherein the mixture angStroms. comprises a Group IV metal organometallic compound and 125. The nanoparticle of claim 96, wherein the nanopar further comprising a rare earth element organometallic com ticle has an average particle diameter distribution of between pound. about 1 and 100 angstroms, and wherein the method further US 2003/0003300 A1 Jan. 2, 2003 29 comprises Subjecting the nanoparticles to a chromatographic 146. The method of claim 145, wherein the metal salt is proceSS Such that particles of different sizes are separated a metal nitrate. from each other. 147. The method of claim 145, wherein the metal salt is 126. A nanoparticle comprising a metal and a capping a metal acetate. agent coupled to the metal, wherein the nanoparticle has an 148. The method of claim 145, wherein the metal salt is average particle diameter of between about 1 to about 100 a transition metal Salt. angstroms, and wherein the capping agent inhibits oxidation 149. The method of claim 145, wherein the metal salt is of the nanoparticle. a copper metal Salt. 127. The nanoparticle of claim 126, wherein the metal is 150. The method of claim 145, wherein the capping agent a Group II metal. is represented by the general formula: 128. The nanoparticle of claim 126, wherein the metal is a Group III metal. 129. The nanoparticle of claim 126, wherein the metal is wherein X is an atom or functional group capable of a Group IV metal. binding to the Surface of the composition; and 130. The nanoparticle of claim 126, wherein the metal is a Group V metal. wherein R is hydrogen, an aryl group having between 131. The nanoparticle of claim 126, wherein the metal is 1 and 10 carbon atoms, or an alkyl group having a Group VI metal. between 1 and 10 carbon atoms; 132. The nanoparticle of claim 126, wherein the metal is n is an integer of at least 1. a transition metal. 151. The method of claim 145, wherein the capping agent 133. The nanoparticle of claim 126, wherein the metal is is an alcohol. an alloy composed of a Group II metal and a Group VI 152. The method of claim 145, wherein the capping agent metal. is an amine. 134. The nanoparticle of claim 126, wherein the metal is 153. The method of claim 145, wherein the capping agent an alloy composed of a Group III metal and a Group V is a thiol. metal. 154. The method of claim 145, wherein the capping agent 135. The nanoparticle of claim 126, wherein the metal is is an alkene. an alloy composed of a Group IV metal and a Group V 155. The method of claim 145, wherein the capping agent metal. is octanol. 136. The nanoparticle of claim 126, wherein the metal is 156. The method of claim 145, further comprising remov an alloy composed of a Group IV metal and a Group III ing the formed nanoparticles from the unreacted metal Salt metal. and capping agent after heating the mixture. 137. The nanoparticle of claim 126, wherein the metal is 157. The method of claim 145, further comprising extract an alloy composed of a Group IV metal and a rare earth ing the formed nanoparticles from the unreacted metal Salt element. and capping agent with a Solvent. 138. The nanoparticle of claim 126, wherein the capping 158. The method of claim 145, further comprising: agent is represented by the general formula: extracting the formed nanoparticles from the unreacted (R), X metal Salt and capping agent with a first Solvent; wherein X is an atom or functional group capable of adding a Second Solvent to the first Solvent to induce binding to the Surface of the composition; and aggregation of the nanoparticles. wherein R is hydrogen, an aryl group having between 159. The method of claim 145, wherein the nanoparticles 1 and 10 carbon atoms, or an alkyl group having have an average particle diameter of less than about 100 between 1 and 10 carbon atoms; angStroms. 160. The method of claim 145, wherein the nanoparticles n is an integer of at least 1. have an average particle diameter distribution of between 139. The nanoparticle of claim 126, wherein the capping about 1 and 100 angstroms, and further comprising Subject agent is an alcohol. ing the nanoparticles to a chromatographic process Such that 140. The nanoparticle of claim 126, wherein the capping particles of different sizes are Separated from each other. agent is an amine. 161. The method of claim 145, wherein the nanoparticles 141. The nanoparticle of claim 126, wherein the capping are metal nanoparticles. agent is a thiol. 162. The method of claim 145, wherein the nanoparticles 142. The nanoparticle of claim 126, wherein the capping are metal oxide nanoparticles. agent is an alkene. 163. A nanoparticle formed by the method comprising 143. The nanoparticle of claim 126, wherein the capping heating a mixture of one or more metal Salts and a capping agent is octanol. agent in Supercritical water, wherein the metal Salts decom 144. The nanoparticle of claim 126, wherein the metal pose forming the nanoparticles. nanoparticle emits visible light in response to an applied 164. The nanoparticle of claim 163, wherein the metal salt Current. is a metal nitrate. 145. A method of forming nanoparticles comprising heat 165. The nanoparticle of claim 163, wherein the metal salt ing a mixture of one or more metal Salts and a capping agent is a metal acetate. in Supercritical water, wherein the metal Salts decompose 166. The nanoparticle of claim 163, wherein the metal salt forming the nanoparticles. is a transition metal Salt. US 2003/0003300 A1 Jan. 2, 2003 30

167. The nanoparticle of claim 163, wherein the metal salt 182. The nanoparticle of claim 179, wherein the capping is a copper metal Salt. agent is an alcohol. 168. The nanoparticle of claim 163, wherein the capping 183. The nanoparticle of claim 179, wherein the capping agent is represented by the general formula: agent is an amine. 184. The nanoparticle of claim 179, wherein the capping (R), X agent is a thiol. wherein X is an atom or functional group capable of 185. The nanoparticle of claim 179, wherein the capping binding to the Surface of the composition; and agent is an alkene. wherein R is hydrogen, an aryl group having between 186. The nanoparticle of claim 179, wherein the capping agent is octanol. 1 and 10 carbon atoms, or an alkyl group having 187. A method of forming nanoparticles in a continuous between 1 and 10 carbon atoms; manner comprising: n is an integer of at least 1. 169. The nanoparticle of claim 163, wherein the capping injecting a mixture of an organometallic precursor and a agent is an alcohol. capping agent into a reactor; 170. The nanoparticle of claim 163, wherein the capping heating the mixture within the reactor to a temperature agent is an amine. wherein the precursor decomposes forming the nano 171. The nanoparticle of claim 163, wherein the capping particles, and agent is a thiol. 172. The nanoparticle of claim 163, wherein the capping removing the formed nanoparticles from the reactor while agent is an alkene. Substantially simultaneously injecting additional orga 173. The nanoparticle of claim 163, wherein the capping nometallic precursors and capping agents into the reac agent is octanol. tor. 174. The nanoparticle of claim 163, wherein the method 188. The method of claim 187, wherein heating the further comprised removing the formed nanoparticles from mixture comprises heating the mixture at a pressure greater the unreacted organometallic precursor and capping agent than 1 atmosphere. after heating the mixture. 189. The method of claim 187, wherein the organome 175. The nanoparticle of claim 163, wherein the method tallic precursor is an organosilane compound. further comprises extracting the formed nanoparticles from 190. The method of claim 187, wherein the organome the unreacted organometallic precursor and capping agent tallic precursor is an organogermanium compound. with a solvent. 191. The method of claim 187, wherein the organome 176. The nanoparticle of claim 163, wherein the method tallic precursor is an alkylsilane. further comprises: 192. The method of claim 187, wherein the organome extracting the formed nanoparticles from the unreacted tallic precursor is an arylsilane. organometallic precursor and capping agent with a first 193. The method of claim 187, wherein the organome Solvent; tallic precursor is tetraethylsilane or diphenylsilane. adding a Second Solvent to the first Solvent to induce 194. The method of claim 187, wherein the capping agent aggregation of the nanoparticles. is represented by the general formula: 177. The nanoparticle of claim 163, wherein the nano (R), X particle has an average particle diameter of less than about 100 angstroms. wherein X is an atom or functional group capable of 178. The nanoparticle of claim 163, wherein the nano binding to the Surface of the composition; and particle has an average particle diameter distribution of wherein R is hydrogen, an aryl group having between between about 1 and 100 angstroms, and wherein the 1 and 10 carbon atoms, or an alkyl group having method further comprises Subjecting the nanoparticles to a between 1 and 10 carbon atoms; chromatographic proceSS Such that particles of different sizes are Separated from each other. n is an integer of at least 1. 179. A nanoparticle comprising a metal oxide and a 195. The method of claim 187, wherein the capping agent capping agent coupled to the metal oxide, wherein the is an alcohol. nanoparticle has an average particle diameter of between 196. The method of claim 187, wherein the capping agent about 1 to about 100 angstroms, and wherein the capping is an amine. agent inhibits oxidation of the nanoparticle. 197. The method of claim 187, wherein the capping agent 180. The nanoparticle of claim 179, wherein the metal is a thiol. oxide is a transition metal oxide. 198. The method of claim 187, wherein the capping agent 181. The nanoparticle of claim 179, wherein the capping is an alkene. agent is represented by the general formula: 199. The method of claim 187, wherein the capping agent is octanol. (R), X 200. The method of claim 187, wherein the mixture wherein X is an atom or functional group capable of further comprises a Solvent. binding to the Surface of the composition; and 201. The method of claim 187, wherein the mixture further comprises a Solvent, and wherein the Solvent is a wherein R is hydrogen, an aryl group having between hydrocarbon. 1 and 10 carbon atoms, or an alkyl group having 202. The method of claim 187, wherein the mixture between 1 and 10 carbon atoms; further comprises a Solvent, and wherein the Solvent is an n is an integer of at least 1. aromatic hydrocarbon. US 2003/0003300 A1 Jan. 2, 2003

203. The method of claim 187, wherein the mixture Group IV metal, wherein the nanoparticles have an further comprises a Solvent, and wherein the Solvent is an average particle diameter of between about 1 to about non-aromatic hydrocarbon. 100 angstroms, and 204. The method of claim 187, wherein the mixture an anode electrically coupled to the plurality of nanopar further comprises a Solvent, and wherein the Solvent is cyclohexane or hexane. ticles, and 205. The method of claim 187, wherein the mixture a cathode electrically coupled to the plurality of nanopar further comprises a Solvent, and further comprising remov ticles, ing entrained oxygen from the Solvent prior to heating the wherein the anode and cathode together are configured to mixture. conduct an applied current to the nanoparticles, 206. The method of claim 187, wherein heating the wherein the nanoparticles produce light in response to mixture comprises heating the organometallic precursor and the applied current. the capping agent at a temperature equal to or greater than 218. The device of claim 217, wherein second electrode the Supercritical temperature of the capping agent. comprises a transparent conductive oxide. 207. The method of claim 187, wherein heating the 219. The device of claim 217, wherein the second elec mixture comprises heating the organometallic precursor and trode comprises a transparent conductive oxide and a Sup the capping agent at a temperature and pressure Such that the porting Substrate, and wherein the transparent conductive capping agent is in a Supercritical State. oxide is formed on the Supporting Substrate. 208. The method of claim 187, wherein the mixture 220. The device of claim 217, wherein the second elec further comprises a Solvent, and wherein heating the mixture trode comprises a transparent conductive oxide and a Sup comprises heating the organometallic precursor, the capping porting Substrate, and wherein the transparent conductive agent, and the Solvent at a temperature equal to or greater oxide is formed on the Supporting Substrate, and wherein the than the Supercritical temperature of the Solvent. Supporting Substrate comprises glass. 209. The method of claim 187, wherein the mixture 221. The device of claim 217, further comprising a further comprises a Solvent, and wherein heating the mixture Supporting host, wherein the nanoparticles are positioned in comprises heating the organometallic precursor, the capping the Supporting host. agent, and the Solvent at a temperature and pressure Such 222. The device of claim 217, further comprising a that the Solvent is in a Supercritical State. Supporting host, wherein the nanoparticles are positioned in 210. The method of claim 187, further comprising remov the Supporting host, and wherein the Supporting host is a ing the formed nanoparticles from the unreacted organome polymer. tallic precursor and capping agent after heating the mixture. 223. The device of claim 217, wherein at least Some of the 211. The method of claim 187, further comprising extract nanoparticles have an average particle diameter of between ing the formed nanoparticles from the unreacted organome about 1 to about 100 angstroms. tallic precursor and capping agent with a Solvent. 224. The device of claim 217, wherein the capping agent inhibits oxidation of the nanoparticles during use. 212. The method of claim 187, further comprising: 225. The device of claim 217, wherein the Group IV metal extracting the formed nanoparticles from the unreacted comprises Silicon. organometallic precursor and capping agent with a first 226. The device of claim 217, wherein the Group IV metal Solvent; comprises germanium. 227. The device of claim 217, wherein the capping agent adding a Second Solvent to the first Solvent to induce aggregation of the nanoparticles. is represented by the general formula: 213. The method of claim 187, wherein the nanoparticles have an average particle diameter of less than about 100 wherein X is an atom or functional group capable of angStroms. binding to the Surface of the composition; and 214. The method of claim 187, wherein the nanoparticles have an average particle diameter distribution of between wherein R is hydrogen, an aryl group having between about 1 and 100 angstroms, and further comprising Subject 1 and 10 carbon atoms, or an alkyl group having ing the nanoparticles to a chromatographic proceSS Such that between 1 and 10 carbon atoms; particles of different sizes are Separated from each other. n is an integer of at least 1. 215. A nanoparticle formed by the method comprising 228. The device of claim 217, wherein the capping agent heating a mixture of one or more organometallic precursors is an alcohol. and a capping agent in a fluid at a temperature above about 229. The device of claim 217, wherein the capping agent 300 C. and below the Supercritical temperature of the fluid. is an amine. 216. A nanoparticle formed by the method comprising 230. The device of claim 217, wherein the capping agent heating a mixture of one or more organometallic precursors is a thiol. and a capping agent in a fluid at a temperature below the 231. The device of claim 217, wherein the capping agent Supercritical temperature of the fluid, wherein the tempera is an alkene. ture of the fluid is not less than about 100° C. below the 232. The device of claim 217, wherein the capping agent Supercritical temperature of the fluid. is octanol. 217. A light emitting device, comprising: 233. A light emitting device, comprising: a plurality of nanoparticles, the nanoparticles comprising a plurality of nanoparticles, formed by the method com a Group IV metal and a capping agent coupled to the prising heating a mixture of a Group IV organometallic US 2003/0003300 A1 Jan. 2, 2003 32

precursor and a capping agent at a temperature wherein 249. The device of claim 233, wherein the capping agent the precursor decomposes, and the nanoparticles are is an amine. formed; 250. The device of claim 233, wherein the capping agent an anode electrically coupled to a plurality of nanopar is a thiol. 251. The device of claim 233, wherein the capping agent ticles, and is an alkene. a cathode electrically coupled to a plurality of nanopar 252. The device of claim 233, wherein the capping agent ticles, is octanol. wherein the anode and cathode together are configured to 253. The device of claim 233, wherein the mixture further conduct an applied current to at least a plurality of the comprises a Solvent. nanoparticles, wherein at least a plurality of the nano 254. The device of claim 233, wherein the mixture further particles produce light in response to the applied cur comprises a Solvent, and wherein the Solvent is a hydrocar rent. bon. 234. The device of claim 233, wherein second electrode 255. The device of claim 233, wherein the mixture further comprises a transparent conductive oxide. comprises a Solvent, and wherein the Solvent is an aromatic 235. The device of claim 233, wherein the second elec hydrocarbon. trode comprises a transparent conductive oxide and a Sup 256. The device of claim 233, wherein the mixture further porting Substrate, and wherein the transparent conductive comprises a Solvent, and wherein the Solvent is a non oxide is formed on the Supporting Substrate. aromatic hydrocarbon. 236. The device of claim 233, wherein the second elec 257. The device of claim 233, wherein the mixture further trode comprises a transparent conductive oxide and a Sup comprises a Solvent, and wherein the Solvent is cyclohexane porting Substrate, and wherein the transparent conductive or hexane. oxide is formed on the Supporting Substrate, and wherein the 258. The device of claim 233, wherein the mixture further Supporting Substrate comprises glass. comprises a Solvent, and wherein the method further com 237. The device of claim 233, further comprising a prises removing entrained oxygen from the Solvent prior to Supporting host, wherein the nanoparticles are positioned in heating the mixture. the Supporting host. 259. The device of claim 233, wherein heating the mixture 238. The device of claim 233, further comprising a comprises heating the organometallic precursor and the Supporting host, wherein the nanoparticles are positioned in capping agent at a temperature equal to or greater than the the Supporting host, and wherein the Supporting host is a Supercritical temperature of the capping agent. polymer. 260. The device of claim 233, wherein heating the mixture 239. The device of claim 233, wherein the nanoparticles comprises heating the organometallic precursor and the have an average particle diameter of between about 1 to capping agent at a temperature and pressure Such that the about 100 angstroms. capping agent is in a Supercritical State. 240. The device of claim 233, wherein the capping agent 261. The device of claim 233, wherein the mixture further inhibits oxidation of the nanoparticles during use. comprises a Solvent, and wherein heating the mixture com 241. The device of claim 233, wherein heating the mixture prises heating the organometallic precursor, the capping comprises heating the mixture at a pressure greater than 1 agent, and the Solvent at a temperature equal to or greater atmosphere. than the Supercritical temperature of the Solvent. 242. The device of claim 233, wherein the Group IV organometallic precursor is an organosilane compound. 262. The device of claim 233, wherein the mixture further 243. The device of claim 233, wherein the Group IV comprises a Solvent, and wherein heating the mixture com organometallic precursor is an organogermanium com prises heating the organometallic precursor, the capping pound. agent, and the Solvent at a temperature and pressure Such 244. The device of claim 233, wherein the Group IV that the Solvent is in a Supercritical State. organometallic precursor is an alkylsilane. 263. The device of claim 233, wherein the method further 245. The device of claim 233, wherein the Group IV comprised removing the formed nanoparticles from the organometallic precursor is an arylsilane. unreacted organometallic precursor and capping agent after 246. The device of claim 233, wherein the Group IV heating the mixture. organometallic precursor is tetraethylsilane or diphenylsi 264. The device of claim 233, wherein the method further lane. comprises extracting the formed nanoparticles from the 247. The device of claim 233, wherein the capping agent unreacted organometallic precursor and capping agent with is represented by the general formula: a Solvent. 265. The device of claim 233, wherein the method further (R), X comprises: wherein X is an atom or functional group capable of extracting the formed nanoparticles from the unreacted binding to the Surface of the composition; and organometallic precursor and capping agent with a first wherein R is hydrogen, an aryl group having between Solvent; 1 and 10 carbon atoms, or an alkyl group having adding a Second Solvent to the first Solvent to induce between 1 and 10 carbon atoms; aggregation of the nanoparticles. n is an integer of at least 1. 266. The device of claim 233, wherein the nanoparticle 248. The device of claim 233, wherein the capping agent has an average particle diameter of less than about 100 is an alcohol. angStroms. US 2003/0003300 A1 Jan. 2, 2003

267. The device of claim 233, wherein the nanoparticle n is an integer of at least 1. has an average particle diameter distribution of between 277. The apparatus of claim 269, wherein the capping about 1 and 100 angstroms, and wherein the method further agent is an alcohol. comprises Subjecting the nanoparticles to a chromatographic 278. The apparatus of claim 269, wherein the capping proceSS Such that particles of different sizes are separated agent is an amine. from each other. 279. The apparatus of claim 269, wherein the capping 268. A light emitting device, comprising: agent is a thiol. 280. The apparatus of claim 269, wherein the capping a plurality of nanoparticles, the nanoparticles comprising agent is an alkene. a metal and a capping agent coupled to the metal, 281. The apparatus of claim 269, wherein the capping wherein the nanoparticles have an average particle agent is octanol. diameter of between about 1 to about 100 angstroms, 282. A display apparatus, comprising: and wherein the capping agent inhibits oxidation of the nanoparticles, and a Support, an anode electrically coupled to the plurality of nanopar an plurality of light emitting devices positioned on the ticles, and Support, wherein the light emitting devices comprise: a plurality of nanoparticles, the nanoparticles formed a cathode electrically coupled to the plurality of nanopar by the method comprising heating a mixture of a ticles, Group IV organometallic precursor and a capping wherein the anode and cathode together are configured to agent at a temperature wherein the precursor decom conduct an applied current to the nanoparticles, poses, and the nanoparticles are formed; wherein the nanoparticles produce light in response to a conductive material electrically coupled to a plurality the applied current. of nanoparticles, wherein the conductive material is 269. A display apparatus, comprising: configured to conduct an applied current to the a Support, nanoparticles, an plurality of light emitting devices positioned on the a controller configured to control the application of cur Support, wherein at least one of the light emitting rent to at least one of the light emitting devices. devices comprise: 283. The apparatus of claim 282, wherein the controller is configured to control the intensity of the light emitting a plurality of nanoparticles, comprising a Group IV devices. metal and a capping agent coupled to the Group IV 284. The apparatus of claim 282, wherein the controller is metal, wherein at least one of the nanoparticles have configured to control the color of the light emitting devices. an average particle diameter of between about 1 to 285. The apparatus of claim 282, further comprising a about 100 angstroms; transparent cover positioned adjacent the array of light a conductive material electrically coupled to a plurality emitting devices. of nanoparticles, wherein the conductive material is 286. The apparatus of claim 282, wherein the nanopar configured to conduct an applied current to the ticles have an average particle diameter of between about 1 nanoparticles, to about 100 angstroms. 287. The apparatus of claim 282, wherein the capping a controller configured to control the application of agent inhibits oxidation of the nanoparticles during use. current to at least one of the light emitting devices. 288. The apparatus of claim 282, wherein heating the 270. The apparatus of claim 269, wherein the controller is mixture comprises heating the mixture at a pressure greater configured to control the intensity of the light emitting than 1 atmosphere. devices. 289. The apparatus of claim 282, wherein the Group IV 271. The apparatus of claim 269, wherein the controller is organometallic precursor is an organosilane compound. configured to control the color of the light emitting devices. 290. The apparatus of claim 282, wherein the Group IV 272. The apparatus of claim 269, further comprising a organometallic precursor is an organogermanium com transparent cover positioned adjacent the array of light pound. emitting devices. 291. The apparatus of claim 282, wherein the Group IV 273. The apparatus of claim 269, wherein the capping organometallic precursor is an alkylsilane. agent inhibits oxidation of the nanoparticles during use. 292. The apparatus of claim 282, wherein the Group IV 274. The apparatus of claim 269, wherein the Group IV organometallic precursor is an arylsilane. metal comprises Silicon. 293. The apparatus of claim 282, wherein the Group IV 275. The apparatus of claim 269, wherein the Group IV organometallic precursor is tetraethylsilane or diphenylsi metal comprises germanium. lane. 276. The apparatus of claim 269, wherein the capping 2.94. The apparatus of claim 282, wherein the capping agent is represented by the general formula: agent is represented by the general formula: (R), X wherein X is an atom or functional group capable of wherein X is an atom or functional group capable of binding to the Surface of the composition; and binding to the Surface of the composition; and wherein R is hydrogen, an aryl group having between wherein R is hydrogen, an aryl group having between 1 and 10 carbon atoms, or an alkyl group having 1 and 10 carbon atoms, or an alkyl group having between 1 and 10 carbon atoms; between 1 and 10 carbon atoms; US 2003/0003300 A1 Jan. 2, 2003 34

n is an integer of at least 1. 313. The apparatus of claim 282, wherein the nanoparticle 295. The apparatus of claim 282, wherein the capping has an average particle diameter of less than about 100 agent is an alcohol. angStroms. 296. The apparatus of claim 282, wherein the capping 314. The apparatus of claim 282, wherein the nanoparticle agent is an amine. has an average particle diameter distribution of between 297. The apparatus of claim 282, wherein the capping about 1 and 100 angstroms, and wherein the method further agent is a thiol. comprises Subjecting the nanoparticles to a chromatographic 298. The apparatus of claim 282, wherein the capping process Such that particles of different sizes are Separated agent is an alkene. from each other. 299. The apparatus of claim 282, wherein the capping 315. A display apparatus, comprising: agent is octanol. a Support, 300. The apparatus of claim 282, wherein the mixture further comprises a Solvent. an plurality of light emitting devices positioned on the 301. The apparatus of claim 282, wherein the mixture Support, wherein the light emitting devices comprise: further comprises a Solvent, and wherein the Solvent is a a plurality of nanoparticles, comprising a metal and a hydrocarbon. capping agent coupled to the metal, wherein at least 302. The apparatus of claim 282, wherein the mixture one of the nanoparticles have an average particle further comprises a Solvent, and wherein the Solvent is an diameter of between about 1 to about 100 angstroms, aromatic hydrocarbon. and wherein the capping agent inhibits oxidation of 303. The apparatus of claim 282, wherein the mixture the nanoparticles, further comprises a Solvent, and wherein the Solvent is a a conductive material electrically coupled to a plurality non-aromatic hydrocarbon. of nanoparticles, wherein the conductive material is 304. The apparatus of claim 282, wherein the mixture configured to conduct an applied current to the further comprises a Solvent, and wherein the Solvent is nanoparticles, cyclohexane or hexane. 305. The apparatus of claim 282, wherein the mixture a controller configured to control the application of cur further comprises a solvent, and wherein the method further rent to each of the light emitting devices comprises removing entrained oxygen from the Solvent prior 316. A System for detecting an analyte in a fluid com to heating the mixture. prising: 306. The apparatus of claim 282, wherein heating the a nanoparticle, comprising a Group IV metal and a mixture comprises heating the organometallic precursor and capping agent coupled to the Group IV metal, wherein the capping agent at a temperature equal to or greater than the nanoparticles have an average particle diameter of the Supercritical temperature of the capping agent. between about 1 to about 100 angstroms; and 307. The apparatus of claim 282, wherein heating the mixture comprises heating the organometallic precursor and a receptor configured to interact with the analyte, wherein the capping agent at a temperature and pressure Such that the the receptor is coupled to at least one of the nanopar capping agent is in a Supercritical State. ticles. 317. The system of claim 316, wherein the capping agent 308. The apparatus of claim 282, wherein the mixture inhibits oxidation of the nanoparticles during use. further comprises a Solvent, and wherein heating the mixture 318. The system of claim 316, further comprising a linker, comprises heating the organometallic precursor, the capping wherein a first end of the linker is coupled to the nanopar agent, and the Solvent at a temperature equal to or greater ticle, and wherein a Second end of the linker is coupled to the than the Supercritical temperature of the Solvent. receptor. 309. The apparatus of claim 282, wherein the mixture 319. The system of claim 316, wherein the Group IV further comprises a Solvent, and wherein heating the mixture metal comprises Silicon. comprises heating the organometallic precursor, the capping 320. The system of claim 316, wherein the Group IV agent, and the Solvent at a temperature and pressure Such metal comprises germanium. that the Solvent is in a Supercritical State. 321. The System of claim 316, wherein the capping agent 310. The apparatus of claim 282, wherein the method is represented by the general formula: further comprised removing the formed nanoparticles from the unreacted organometallic precursor and capping agent (R), X after heating the mixture. wherein X is an atom or functional group capable of 311. The apparatus of claim 282, wherein the method binding to the Surface of the composition; and further comprises extracting the formed nanoparticles from the unreacted organometallic precursor and capping agent wherein R is hydrogen, an aryl group having between with a solvent. 1 and 10 carbon atoms, or an alkyl group having 312. The apparatus of claim 282, wherein the method between 1 and 10 carbon atoms; further comprises: n is an integer of at least 1. extracting the formed nanoparticles from the unreacted 322. The System of claim 316, wherein the capping agent organometallic precursor and capping agent with a first is an alcohol. 323. The System of claim 316, wherein the capping agent Solvent; is an amine. adding a Second Solvent to the first Solvent to induce 324. The System of claim 316, wherein the capping agent aggregation of the nanoparticles. is a thiol. US 2003/0003300 A1 Jan. 2, 2003

325. The system of claim 316, wherein the capping agent 348. The system of claim 341, wherein the Group IV is an alkene. organometallic precursor is an alkylsilane. 326. The System of claim 316, wherein the capping agent 349. The system of claim 341, wherein the Group IV is octanol organometallic precursor is an arylsilane. 327. The system of claim 316, wherein the receptor 350. The system of claim 341, wherein the Group IV comprises a polynucleotide. organometallic precursor is tetraethylsilane or diphenylsi 328. The system of claim 316, wherein the receptor lane. comprises a peptide. 351. The system of claim 341, wherein the capping agent 329. The system of claim 316, wherein the receptor is represented by the general formula: comprises an enzyme. 330. The system of claim 316, wherein the receptor comprises a Synthetic receptor. wherein X is an atom or functional group capable of 331. The system of claim 316, wherein the receptor binding to the Surface of the composition; and comprises an unnatural biopolymer. wherein R is hydrogen, an aryl group having between 332. The system of claim 316, wherein the receptor 1 and 10 carbon atoms, or an alkyl group having comprises an antibody. between 1 and 10 carbon atoms; 333. The system of claim 316, wherein the receptor comprises an antigen. n is an integer of at least 1. 334. The system of claim 316, further comprising a linker, 352. The System of claim 341, wherein the capping agent wherein a first end of the linker is coupled to the nanopar is an alcohol. ticle, and wherein a Second end of the linker is coupled to the 353. The system of claim 341, wherein the capping agent receptor, and wherein the linker comprises a peptide. is an amine. 335. The system of claim 316, further comprising a linker, 354. The system of claim 341, wherein the capping agent wherein a first end of the linker is coupled to the nanopar is a thiol. ticle, and wherein a Second end of the linker is coupled to the 355. The system of claim 341, wherein the capping agent receptor, and wherein the linker comprises a peptide is an alkene. mimetic. 356. The system of claim 341, wherein the capping agent 336. The system of claim 316, wherein the analyte com is octanol. prises a metal ion. 357. The system of claim 341, wherein the mixture further 337. The System of claim 316, wherein the analyte com comprises a Solvent. prises a phosphate functional groups. 358. The system of claim 341, wherein the mixture further 338. The system of claim 316, wherein the analyte com comprises a Solvent, and wherein the Solvent is a hydrocar prises a bacterium. bon. 359. The system of claim 341, wherein the mixture further 339. The system of claim 316, wherein the analyte com comprises a Solvent, and wherein the Solvent is an aromatic prises a protease. hydrocarbon. 340. The system of claim 316, wherein the analyte com prises a nuclease. 360. The system of claim 341, wherein the mixture further 341. A System for detecting an analyte in a fluid com comprises a Solvent, and wherein the Solvent is an non prising: aromatic hydrocarbon. 361. The system of claim 341, wherein the mixture further a nanoparticle, formed by the method comprising heating comprises a Solvent, and wherein the Solvent is cyclohexane a mixture of a Group IV organometallic precursor and or hexane. a capping agent at a temperature wherein the precursor 362. The system of claim 341, wherein the mixture further decomposes, and the nanoparticle is formed; and comprises a Solvent, and wherein the method further com prises removing entrained oxygen from the Solvent prior to a receptor configured to interact with the analyte, wherein heating the mixture. the receptor is coupled to the nanoparticle. 363. The system of claim 341, wherein heating the 342. The system of claim 341, wherein the nanoparticles mixture comprises heating the organometallic precursor and have an average particle diameter of between about 1 to the capping agent at a temperature equal to or greater than about 100 angstroms. the Supercritical temperature of the capping agent. 343. The system of claim 341, further comprising a linker, 364. The system of claim 341, wherein heating the wherein a first end of the linker is coupled to the nanopar mixture comprises heating the organometallic precursor and ticle, and wherein a Second end of the linker is coupled to the the capping agent at a temperature and preSSure Such that the receptor. capping agent is in a Supercritical State. 344. The System of claim 341, wherein the capping agent 365. The system of claim 341, wherein the mixture further inhibits oxidation of the nanoparticles during use. comprises a Solvent, and wherein heating the mixture com 345. The system of claim 341, wherein heating the prises heating the organometallic precursor, the capping mixture comprises heating the mixture at a pressure greater agent, and the Solvent at a temperature equal to or greater than 1 atmosphere. than the Supercritical temperature of the Solvent. 346. The system of claim 341, wherein the Group IV 366. The system of claim 341, wherein the mixture further organometallic precursor is an organosilane compound. comprises a Solvent, and wherein heating the mixture com 347. The system of claim 341, wherein the Group IV prises heating the organometallic precursor, the capping organometallic precursor is an organogermanium com agent, and the Solvent at a temperature and pressure Such pound. that the Solvent is in a Supercritical State. US 2003/0003300 A1 Jan. 2, 2003 36

367. The system of claim 341, wherein the method further between about 1 to about 100 angstroms, and wherein comprised removing the formed nanoparticles from the the capping agent inhibits oxidation of the nanopar unreacted organometallic precursor and capping agent after ticles, and heating the mixture. 368. The system of claim 341, wherein the method further a receptor configured to interact with the analyte, wherein comprises extracting the formed nanoparticles from the the receptor is coupled to at least one of the nanopar unreacted organometallic precursor and capping agent with ticles. a Solvent. 387. A memory device, comprising: 369. The system of claim 341, wherein the method further a Source configured to apply an electrical charge, comprises: a drain configured to hold an electric charge, extracting the formed nanoparticles from the unreacted organometallic precursor and capping agent with a first a channel configured to Separate the Source and the drain; Solvent; a floating gate positioned above the channel, the floating adding a Second Solvent to the first Solvent to induce gate comprising a plurality of nanoparticles, wherein at aggregation of the nanoparticles. least a plurality of the nanoparticles comprises a Group 370. The system of claim 341, wherein the nanoparticle IV metal and a capping agent coupled to the Group IV has an average particle diameter of less than about 100 metal, wherein at least one of the nanoparticles have an angStroms. average particle diameter of between about 1 to about 371. The system of claim 341, wherein the nanoparticle 100 angstroms, has an average particle diameter distribution of between a control gate positioned Substantially adjacent the float about 1 and 100 angstroms, and wherein the method further ing gate; and comprises Subjecting the nanoparticles to a chromatographic proceSS Such that particles of different sizes are separated a conductor comprising an oxide positioned between the from each other. control gate and the floating gate; 372. The system of claim 341, wherein the receptor wherein the floating gate is positioned between the chan comprises a polynucleotide. nel and the control gate. 373. The system of claim 341, wherein the receptor 388. The device of claim 387, wherein the floating gate is comprises a peptide. electrically isolated. 374. The system of claim 341, wherein the receptor 389. The device of claim 387, wherein the nanoparticle comprises an enzyme. further comprises a doping agent. 375. The system of claim 341, wherein the receptor 390. The device of claim 387, further comprising a comprises a Synthetic receptor. Supporting host, wherein the nanoparticle is positioned in 376. The system of claim 341, wherein the receptor the Supporting host. comprises an unnatural biopolymer. 391. The device of claim 387, further comprising a 377. The system of claim 341, wherein the receptor Supporting host, wherein the nanoparticle is positioned in comprises an antibody. the Supporting host, and wherein the Supporting host is a 378. The system of claim 341, wherein the receptor polymer. comprises an antigen. 392. The device of claim 387, wherein the Group IV metal 379. The system of claim 341, further comprising a linker, comprises Silicon. wherein a first end of the linker is coupled to the nanopar 393. The device of claim 387, wherein the Group IV metal ticle, and wherein a Second end of the linker is coupled to the comprises germanium. receptor, and wherein the linker compress a peptide. 394. The device of claim 387, wherein the capping agent 380. The system of claim 341, further comprising a linker, is represented by the general formula: wherein a first end of the linker is coupled to the nanopar ticle, and wherein a Second end of the linker is coupled to the receptor, and wherein the linker comprises a peptide wherein X is an atom or functional group capable of mimetic. binding to the Surface of the nanoparticle; and 381. The system of claim 341, wherein the analyte com prises a metal ion. wherein R is hydrogen, an aryl group having between 382. The system of claim 341, wherein the analyte com 1 and 10 carbon atoms, or an alkyl group having prises a phosphate functional groups. between 1 and 10 carbon atoms; 383. The system of claim 341, wherein the analyte com n is an integer of at least 1. prises a bacterium. 395. The device of claim 387, wherein the capping agent 384. The system of claim 341, wherein the analyte com is an alcohol. prises a protease. 396. The device of claim 387, wherein the capping agent 385. The system of claim 341, wherein the analyte com is an amine. prises a nuclease. 397. The device of claim 387, wherein the capping agent 386. A system for detecting an analyte in a fluid com is a thiol. prising: 398. The device of claim 387, wherein the capping agent a nanoparticle, comprising a metal and a capping agent is an alkene. coupled to the metal, wherein at least one of the 399. The device of claim 387, wherein the capping agent nanoparticles have an average particle diameter of is octanol. US 2003/0003300 A1 Jan. 2, 2003 37

400. The device of claim 387, wherein the metal nano 416. The device of claim 401, wherein the capping agent particle emits visible light in response to an applied current. is an alcohol. 401. A memory device, comprising: 417. The device of claim 401, wherein the capping agent a Source configured to apply an electrical charge; is an amine. 418. The device of claim 401, wherein the capping agent a drain configured to hold an electric charge, is a thiol. a channel configured to Separate the Source and the drain; 419. The device of claim 401, wherein the capping agent is an alkene. a floating gate positioned above the channel, the floating gate comprising a plurality of nanoparticles, formed by 420. The device of claim 401, wherein the capping agent the method comprising heating a mixture of a Group IV is octanol. organometallic precursor and a capping agent at a 421. The device of claim 401, wherein the mixture further temperature wherein the precursor decomposes, and the comprises a Solvent. nanoparticles are formed; 422. The device of claim 401, wherein the mixture further comprises a Solvent, and wherein the Solvent is a hydrocar a control gate positioned Substantially adjacent the float bon. ing gate; and 423. The device of claim 401, wherein the mixture further a conductor comprising an oxide positioned between the comprises a Solvent, and wherein the Solvent is an aromatic control gate and the floating gate; hydrocarbon. wherein the floating gate is positioned between the chan 424. The device of claim 401, wherein the mixture further nel and the control gate. comprises a Solvent, and wherein the Solvent is a non 402. The device of claim 401, wherein the floating gate is aromatic hydrocarbon. electrically isolated. 425. The device of claim 401, wherein the mixture further 403. The device of claim 401, wherein the Group IV metal comprises a Solvent, and wherein the Solvent is cyclohexane element is Silicon or hexane. 404. The device of claim 401, wherein the nanoparticle 426. The device of claim 401, wherein the mixture further further comprises a doping agent. comprises a Solvent, and wherein the method further com 405. The device of claim 401, further comprising a prises removing entrained oxygen from the Solvent prior to Supporting host, wherein the nanoparticle is positioned in heating the mixture. the Supporting host. 427. The device of claim 401, wherein heating the mixture 406. The device of claim 401, further comprising a comprises heating the organometallic precursor and the Supporting host, wherein the nanoparticle is positioned in capping agent at a temperature equal to or greater than the the Supporting host, and wherein the Supporting host is a Supercritical temperature of the capping agent. polymer. 407. The device of claim 401, wherein the nanoparticles 428. The device of claim 401, wherein heating the mixture have an average particle diameter of between about 1 to comprises heating the organometallic precursor and the about 100 angstroms. capping agent at a temperature and pressure Such that the 408. The device of claim 401, wherein the capping agent capping agent is in a Supercritical State. inhibits oxidation of the nanoparticles during use. 429. The device of claim 401, wherein the mixture further 409. The device of claim 401, wherein heating the mixture comprises a Solvent, and wherein heating the mixture com comprises heating the mixture at a pressure greater than 1 prises heating the organometallic precursor, the capping atmosphere. agent, and the Solvent at a temperature equal to or greater 410. The device of claim 401, wherein the Group IV than the Supercritical temperature of the Solvent. organometallic precursor is an organosilane compound. 430. The device of claim 401, wherein the mixture further 411. The device of claim 401, wherein the Group IV comprises a Solvent, and wherein heating the mixture com organometallic precursor is an organogermanium com prises heating the organometallic precursor, the capping pound. agent, and the Solvent at a temperature and pressure Such 412. The device of claim 401, wherein the Group IV that the Solvent is in a Supercritical State. organometallic precursor is an alkylsilane. 431. The device of claim 401, wherein the method further 413. The device of claim 401, wherein the Group IV comprised removing the formed nanoparticles from the organometallic precursor is an arylsilane. unreacted organometallic precursor and capping agent after 414. The device of claim 401, wherein the Group IV organometallic precursor is tetraethylsilane or diphenylsi heating the mixture. lane. 432. The device of claim 401, wherein the method further 415. The device of claim 401, wherein the capping agent comprises extracting the formed nanoparticles from the is represented by the general formula: unreacted organometallic precursor and capping agent with a Solvent. (R), X 433. The device of claim 401, wherein the method further wherein X is an atom or functional group capable of comprises: binding to the Surface of the composition; and extracting the formed nanoparticles from the unreacted wherein R is hydrogen, an aryl group having between organometallic precursor and capping agent with a first 1 and 10 carbon atoms, or an alkyl group having Solvent; between 1 and 10 carbon atoms; adding a Second Solvent to the first Solvent to induce n is an integer of at least 1. aggregation of the nanoparticles. US 2003/0003300 A1 Jan. 2, 2003 38

434. The device of claim 401, wherein the nanoparticle 443. The device of claim 438, wherein the capping agent has an average particle diameter of less than about 100 is represented by the general formula: angStroms. 435. The device of claim 401, wherein the nanoparticle has an average particle diameter distribution of between wherein X is an atom or functional group capable of about 1 and 100 angstroms, and wherein the method further binding to the Surface of the nanoparticle; and comprises Subjecting the nanoparticles to a chromatographic proceSS Such that particles of different sizes are separated wherein R is hydrogen, an aryl group having between from each other. 1 and 10 carbon atoms, or an alkyl group having 436. A memory device, comprising: between 1 and 10 carbon atoms; n is an integer of at least 1. a Source configured to apply an electrical charge; 444. The device of claim 438, wherein the capping agent a drain configured to hold an electric charge, is an alcohol. 445. The device of claim 438, wherein the capping agent a channel configured to Separate the Source and the drain; is an amine. a floating gate positioned above the channel, the floating 446. The device of claim 438, wherein the capping agent gate comprising a plurality of nanoparticles, the nano is a thiol. particles comprising a metal and a capping agent 447. The device of claim 438, wherein the capping agent coupled to the metal, wherein at least one of the is an alkene. nanoparticles have an average particle diameter of 448. The device of claim 438, wherein the capping agent between about 1 to about 100 angstroms, and wherein is octanol. the capping agent inhibits oxidation of the nanopar 449. The device of claim 438, wherein the metal nano ticles, particle emits visible light in response to an applied current. 450. A coherent light emitting device, comprising: a control gate positioned Substantially adjacent the float ing gate; and a plurality of nanoparticles, formed by the method com prising heating a mixture of a Group IV organometallic a conductor comprising an oxide positioned between the precursor and a capping agent at a temperature wherein control gate and the floating gate; the precursor decomposes, and the nanoparticles are wherein the floating gate is positioned between the chan formed; nel and the control gate. an excitation Source configured to apply energy to at least 437. A floating gate device, comprising a plurality of one of the nanoparticles in an absorbable form; and nanoparticles, the nanoparticles comprising a Group IV metal and a capping agent coupled to the Group IV metal, an optical cavity configured to direct light; wherein the nanoparticles have an average particle diameter wherein when the excitation Source applies energy to one of between about 1 to about 100 angstroms. or more nanoparticles the one or more nanoparticles 438. A coherent light emitting device, comprising: produce light, and wherein light produced by the one or a plurality of nanoparticles, comprising a Group IV metal more nanoparticles is directed by the optical cavity. and a capping agent coupled to the Group IV metal, 451. The device of claim 450, wherein the optical cavity wherein at least one of the nanoparticles have an comprises a first reflective device and a Second reflective average particle diameter of between about 1 to about device. 100 angstroms, 452. The device of claim 450, wherein the optical cavity comprises a first reflective device and a Second reflective an excitation Source configured to apply energy to the device, and wherein the first reflective device is configured nanoparticles in an absorbable form; to reflect light within the optical cavity, and wherein the Second reflective device is configured to allow a portion of an optical cavity configured to direct light; and the light within the optical cavity to leave the optical cavity. wherein when the excitation Source applies energy to 453. The device of claim 450, wherein the nanoparticles nanoparticles the nanoparticles produce light, and have an average particle diameter of between about 1 to wherein light produced by the nanoparticles is directed about 100 angstroms. by the optical cavity. 454. The device of claim 450, wherein the capping agent 439. The device of claim 438, wherein the optical cavity inhibits oxidation of the nanoparticles during use. comprises a first reflective device and a Second reflective 455. The device of claim 450, wherein heating the mixture device. comprises heating the mixture at a pressure greater than 1 440. The device of claim 438, wherein the optical cavity atmosphere. comprises a first reflective device and a Second reflective 456. The device of claim 450, wherein the Group IV device, and wherein the first reflective device is configured organometallic precursor is an organosilane compound. to reflect light within the optical cavity, and wherein the 457. The device of claim 450, wherein the Group IV Second reflective device is configured to allow a portion of organometallic precursor is an organogermanium com the light within the optical cavity to leave the optical cavity. pound. 441. The device of claim 438, wherein the Group IV metal 458. The device of claim 450, wherein the Group IV comprises Silicon. organometallic precursor is an alkylsilane. 442. The device of claim 438, wherein the Group IV metal 459. The device of claim 450, wherein the Group IV comprises germanium. organometallic precursor is an arylsilane. US 2003/0003300 A1 Jan. 2, 2003 39

460. The device of claim 450, wherein the Group IV 478. The device of claim 450, wherein the method further organometallic precursor is tetraethylsilane or diphenylsi comprises extracting the formed nanoparticles from the lane. unreacted organometallic precursor and capping agent with 461. The device of claim 450, wherein the capping agent a Solvent. is represented by the general formula: 479. The device of claim 450, wherein the method further comprises: (R), X extracting the formed nanoparticles from the unreacted wherein X is an atom or functional group capable of organometallic precursor and capping agent with a first binding to the Surface of the composition; and Solvent; wherein R is hydrogen, an aryl group having between adding a Second Solvent to the first Solvent to induce 1 and 10 carbon atoms, or an alkyl group having aggregation of the nanoparticles. 480. The device of claim 450, wherein the nanoparticle between 1 and 10 carbon atoms; has an average particle diameter of less than about 100 n is an integer of at least 1. angStroms. 462. The device of claim 450, wherein the capping agent 481. The device of claim 450, wherein the nanoparticle is an alcohol. has an average particle diameter distribution of between about 1 and 100 angstroms, and wherein the method further 463. The device of claim 450, wherein the capping agent comprises Subjecting the nanoparticles to a chromatographic is an amine. process Such that particles of different sizes are Separated 464. The device of claim 450, wherein the capping agent from each other. is a thiol. 482. A coherent light emitting device, comprising: 465. The device of claim 450, wherein the capping agent is an alkene. a plurality of nanoparticles, comprising a metal and a 466. The device of claim 450, wherein the capping agent capping agent coupled to the metal, wherein at least one is octanol. of the nanoparticles have an average particle 467. The device of claim 450, wherein the mixture further diameter of between about 1 to about 100 angstroms, and comprises a Solvent. wherein the capping agent inhibits oxidation of the 468. The device of claim 450, wherein the mixture further nanoparticles, comprises a Solvent, and wherein the Solvent is a hydrocar bon. an excitation Source configured to apply energy to at least 469. The device of claim 450, wherein the mixture further one of the nanoparticles in an absorbable form; and comprises a Solvent, and wherein the Solvent is an aromatic an optical cavity configured to direct light; hydrocarbon. wherein when the excitation Source applies energy to one 470. The device of claim 450, wherein the mixture further or more nanoparticles the one or more nanoparticles comprises a Solvent, and wherein the Solvent is a non produce light, and wherein light produced by the one or aromatic hydrocarbon. more nanoparticles is directed by the optical cavity. 471. The device of claim 450, wherein the mixture further 483. A System for at least partially containing an electrical comprises a Solvent, and wherein the Solvent is cyclohexane charge temporarily, comprising: or hexane. 472. The device of claim 450, wherein the mixture further a cathode comprising a plurality of nanoparticles, com comprises a Solvent, and wherein the method further com prising a Group IV metal and a capping agent coupled prises removing entrained oxygen from the Solvent prior to to the Group IV metal, wherein at least one of the heating the mixture. nanoparticles have an average particle diameter of 473. The device of claim 450, wherein heating the mixture between about 1 to about 100 angstroms, and wherein comprises heating the organometallic precursor and the the nanoparticles are electroactive, capping agent at a temperature equal to or greater than the an anode comprising an electroactive material; and Supercritical temperature of the capping agent. 474. The device of claim 450, wherein heating the mixture a separator positioned between the cathode and the anode comprises heating the organometallic precursor and the configured to inhibit contact between a portion of the capping agent at a temperature and pressure Such that the cathode and a portion of the anode. capping agent is in a Supercritical State. 484. The system of claim 483, further comprising a first 475. The device of claim 450, wherein the mixture further collector and a Second collector. comprises a Solvent, and wherein heating the mixture com 485. The system of claim 483, further comprising a first prises heating the organometallic precursor, the capping collector and a Second collector, wherein the first collector agent, and the Solvent at a temperature equal to or greater is positioned adjacent the cathode and configured to facili tate flow of electricity from the device, and wherein the than the Supercritical temperature of the Solvent. Second collector is positioned adjacent the anode and con 476. The device of claim 450, wherein the mixture further figured to facilitate flow of electricity from the device. comprises a Solvent, and wherein heating the mixture com 486. The system of claim 483, wherein the Group IV prises heating the organometallic precursor, the capping metal comprises Silicon. agent, and the Solvent at a temperature and pressure Such 487. The system of claim 483, wherein the Group IV that the Solvent is in a Supercritical State. metal comprises germanium. 477. The device of claim 450, wherein the method further comprised removing the formed nanoparticles from the 488. The system of claim 483, wherein the capping agent unreacted organometallic precursor and capping agent after is represented by the general formula: heating the mixture. US 2003/0003300 A1 Jan. 2, 2003 40

wherein X is an atom or functional group capable of wherein R is hydrogen, an aryl group having between binding to the Surface of the nanoparticle; and 1 and 10 carbon atoms, or an alkyl group having wherein R is hydrogen, an aryl group having between between 1 and 10 carbon atoms; 1 and 10 carbon atoms, or an alkyl group having n is an integer of at least 1. between 1 and 10 carbon atoms; 507. The system of claim 495, wherein the capping agent n is an integer of at least 1. is an alcohol. 489. The system of claim 483, wherein the capping agent 508. The system of claim 495, wherein the capping agent is an alcohol. is an amine. 490. The system of claim 483, wherein the capping agent 509. The system of claim 495, wherein the capping agent is an amine. is a thiol. 491. The system of claim 483, wherein the capping agent 510. The system of claim 495, wherein the capping agent is a thiol. is an alkene. 492. The system of claim 483, wherein the capping agent 511. The system of claim 495, wherein the capping agent is an alkene. is octanol. 493. The system of claim 483, wherein the capping agent 512. The system of claim 495, wherein the mixture further is octanol. comprises a Solvent. 494. The system of claim 483, wherein the metal nano 513. The system of claim 495, wherein the mixture further particle emits visible light in response to an applied current. comprises a Solvent, and wherein the Solvent is a hydrocar 495. A System for at least partially containing an electrical bon. charge temporarily, comprising: 514. The system of claim 495, wherein the mixture further comprises a Solvent, and wherein the Solvent is an aromatic a cathode comprising a plurality of nanoparticles, formed hydrocarbon. by the method comprising heating a mixture of a Group 515. The system of claim 495, wherein the mixture further IV organometallic precursor and a capping agent at a comprises a Solvent, and wherein the Solvent is a non temperature wherein the precursor decomposes, and the aromatic hydrocarbon. nanoparticles are formed, wherein the nanoparticles are 516. The system of claim 495, wherein the mixture further electroactive; comprises a Solvent, and wherein the Solvent is cyclohexane an anode comprising an electroactive material; and or hexane. 517. The system of claim 495, wherein the mixture further a separator positioned between the cathode and the anode comprises a Solvent, and wherein the method further com configured to inhibit contact between a portion of the prises removing entrained oxygen from the Solvent prior to cathode and a portion of the anode. heating the mixture. 496. The system of claim 495, further comprising a first 518. The system of claim 495, wherein heating the collector and a Second collector. mixture comprises heating the organometallic precursor and 497. The system of claim 495, further comprising a first the capping agent at a temperature equal to or greater than collector and a Second collector, wherein the first collector the Supercritical temperature of the capping agent. is positioned adjacent the cathode and configured to facili 519. The system of claim 495, wherein heating the tate flow of electricity from the device, and wherein the mixture comprises heating the organometallic precursor and Second collector is positioned adjacent the anode and con the capping agent at a temperature and preSSure Such that the figured to facilitate flow of electricity from the device. capping agent is in a Supercritical State. 498. The system of claim 495, wherein the nanoparticles 520. The system of claim 495, wherein the mixture further have an average particle diameter of between about 1 to comprises a Solvent, and wherein heating the mixture com about 100 angstroms. prises heating the organometallic precursor, the capping 499. The system of claim 495, wherein the capping agent agent, and the Solvent at a temperature equal to or greater inhibits oxidation of the nanoparticles during use. than the Supercritical temperature of the Solvent. 500. The system of claim 495, wherein heating the 521. The system of claim 495, wherein the mixture further mixture comprises heating the mixture at a pressure greater comprises a Solvent, and wherein heating the mixture com than 1 atmosphere. prises heating the organometallic precursor, the capping 501. The system of claim 495, wherein the Group IV agent, and the Solvent at a temperature and pressure Such organometallic precursor is an organosilane compound. that the Solvent is in a Supercritical State. 502. The system of claim 495, wherein the Group IV 522. The system of claim 495, wherein the method further organometallic precursor is an organogermanium com comprised removing the formed nanoparticles from the pound. unreacted organometallic precursor and capping agent after 503. The system of claim 495, wherein the Group IV heating the mixture. organometallic precursor is an alkylsilane. 523. The system of claim 495, wherein the method further 504. The system of claim 495, wherein the Group IV comprises extracting the formed nanoparticles from the organometallic precursor is an arylsilane. unreacted organometallic precursor and capping agent with 505. The system of claim 495, wherein the Group IV a Solvent. organometallic precursor is tetraethylsilane or diphenylsi 524. The system of claim 495, wherein the method further lane. comprises: 506. The system of claim 495, wherein the capping agent extracting the formed nanoparticles from the unreacted is represented by the general formula: organometallic precursor and capping agent with a first (R), X Solvent; wherein X is an atom or functional group capable of adding a Second Solvent to the first Solvent to induce binding to the Surface of the composition; and aggregation of the nanoparticles. US 2003/0003300 A1 Jan. 2, 2003

525. The system of claim 495, wherein the nanoparticle 539. The system of claim 528, wherein the receptor has an average particle diameter of less than about 100 comprises a polynucleotide. angStroms. 540. The system of claim 528, wherein the receptor 526. The system of claim 495, wherein the nanoparticle comprises a peptide. has an average particle diameter distribution of between 541. The system of claim 528, wherein the receptor about 1 and 100 angstroms, and wherein the method further comprises an enzyme. comprises Subjecting the nanoparticles to a chromatographic 542. The system of claim 528, wherein the receptor proceSS Such that particles of different sizes are separated comprises a Synthetic receptor. from each other. 543. The system of claim 528, wherein the receptor 527. A System for at least partially containing an electrical comprises an unnatural biopolymer. charge temporarily, comprising: 544. The system of claim 528, wherein the receptor a cathode comprising a plurality of nanoparticles, com comprises an antibody. prising a metal and a capping agent coupled to the 545. The system of claim 528, wherein the receptor metal, wherein at least one of the nanoparticles have an comprises an antigen. average particle diameter of between about 1 to about 546. The system of claim 528, further comprising a linker, 100 angstroms, and wherein the capping agent inhibits wherein a first end of the linker is coupled to the nanopar oxidation of the nanoparticles, and wherein the nano ticle, and wherein a Second end of the linker is coupled to the particles are electroactive; receptor, and wherein the linker comprises a peptide. 547. The system of claim 528, further comprising a linker, an anode comprising an electroactive material; and wherein a first end of the linker is coupled to the nanopar a separator positioned between the cathode and the anode ticle, and wherein a Second end of the linker is coupled to the configured to inhibit contact between a portion of the receptor, and wherein the linker comprises a peptide cathode and a portion of the anode. mimetic. 528. A system for electrically communicating with a 548. The system of claim 528, wherein the analyte com biological entity comprising: prises a metal ion. 549. The system of claim 528, wherein the analyte com a nanoparticle, comprising a Group IV metal and a prises a phosphate functional groups. capping agent coupled to the Group IV metal, wherein 550. The system of claim 528, wherein the analyte com at least one of the nanoparticles have an average prises a bacterium. particle diameter of between about 1 to about 100 551. The system of claim 528, wherein the analyte com angstroms, and wherein at least one of the nanopar prises a protease. ticles produces an electric field in response to a stimu 552. The system of claim 528, wherein the analyte com lus, and prises a nuclease. a receptor configured to interact with the biological entity, 553. A system for electrically communicating with a wherein the receptor is coupled to the nanoparticle. biological entity comprising: 529. The system of claim 528, further comprising a linker, a nanoparticle, formed by the method comprising heating wherein a first end of the linker is coupled to the nanopar a mixture of a Group IV organometallic precursor and ticle, and wherein a Second end of the linker is coupled to the a capping agent at a temperature wherein the precursor receptor. decomposes, and the nanoparticle is formed, and 530. The system of claim 528, wherein the capping agent wherein at least one of the nanoparticles produces an inhibits oxidation of the nanoparticles during use. electric field in response to a stimulus, and 531. The system of claim 528, wherein the Group IV metal comprises Silicon. a receptor configured to interact with the biological entity, 532. The system of claim 528, wherein the Group IV wherein the receptor is coupled to at least one of the metal comprises germanium. nanoparticles. 533. The system of claim 528, wherein the capping agent 554. The system of claim 553, further comprising a linker, is represented by the general formula: wherein a first end of the linker is coupled to the nanopar ticle, and wherein a Second end of the linker is coupled to the (R), X receptor. wherein X is an atom or functional group capable of 555. The system of claim 553, wherein the nanoparticles binding to the Surface of the composition; and have an average particle diameter of between about 1 to about 100 angstroms. wherein R is hydrogen, an aryl group having between 556. The system of claim 553, wherein the capping agent 1 and 10 carbon atoms, or an alkyl group having inhibits oxidation of the nanoparticles during use. between 1 and 10 carbon atoms; 557. The system of claim 553, wherein heating the n is an integer of at least 1. mixture comprises heating the mixture at a pressure greater 534. The system of claim 528, wherein the capping agent than 1 atmosphere. is an alcohol. 558. The system of claim 553, wherein the Group IV 535. The system of claim 528, wherein the capping agent organometallic precursor is an organosilane compound. is an amine. 559. The system of claim 553, wherein the Group IV 536. The system of claim 528, wherein the capping agent organometallic precursor is an organogermanium com is a thiol. pound. 537. The system of claim 528, wherein the capping agent 560. The system of claim 553, wherein the Group IV is an alkene. organometallic precursor is an alkylsilane. 538. The system of claim 528, wherein the capping agent 561. The system of claim 553, wherein the Group IV is octanol organometallic precursor is an arylsilane. US 2003/0003300 A1 Jan. 2, 2003 42

562. The system of claim 553, wherein the Group IV 580. The system of claim 553, wherein the method further organometallic precursor is tetraethylsilane or diphenylsi comprises extracting the formed nanoparticles from the lane. unreacted organometallic precursor and capping agent with 563. The system of claim 553, wherein the capping agent a Solvent. is represented by the general formula: 581. The system of claim 553, wherein the method further comprises: (R), X extracting the formed nanoparticles from the unreacted wherein X is an atom or functional group capable of organometallic precursor and capping agent with a first binding to the Surface of the composition; and Solvent; wherein R is hydrogen, an aryl group having between adding a Second Solvent to the first Solvent to induce 1 and 10 carbon atoms, or an alkyl group having aggregation of the nanoparticles. between 1 and 10 carbon atoms; 582. The system of claim 553, wherein the nanoparticle has an average particle diameter of less than about 100 n is an integer of at least 1. angStroms. 564. The system of claim 553, wherein the capping agent 583. The system of claim 553, wherein the nanoparticle is an alcohol. has an average particle diameter distribution of between 565. The system of claim 553, wherein the capping agent about 1 and 100 angstroms, and wherein the method further is an amine. comprises Subjecting the nanoparticles to a chromatographic 566. The system of claim 553, wherein the capping agent process Such that particles of different sizes are Separated is a thiol. from each other. 584. The system of claim 553, wherein the receptor 567. The system of claim 553, wherein the capping agent comprises a polynucleotide. is an alkene. 585. The system of claim 553, wherein the receptor 568. The system of claim 553, wherein the capping agent comprises a peptide. is octanol. 586. The system of claim 553, wherein the receptor 569. The system of claim 553, wherein the mixture further comprises an enzyme. comprises a Solvent. 587. The system of claim 553, wherein the receptor 570. The system of claim 553, wherein the mixture further comprises a Synthetic receptor. comprises a Solvent, and wherein the Solvent is a hydrocar 588. The system of claim 553, wherein the receptor bon. comprises an unnatural biopolymer. 571. The system of claim 553, wherein the mixture further 589. The system of claim 553, wherein the receptor comprises a Solvent, and wherein the Solvent is an aromatic comprises an antibody. hydrocarbon. 590. The system of claim 553, wherein the receptor 572. The system of claim 553, wherein the mixture further comprises an antigen. comprises a Solvent, and wherein the Solvent is an non 591. The system of claim 553, further comprising a linker, aromatic hydrocarbon. wherein a first end of the linker is coupled to the nanopar ticle, and wherein a Second end of the linker is coupled to the 573. The system of claim 553, wherein the mixture further receptor, and wherein the linker comprises a peptide. comprises a Solvent, and wherein the Solvent is cyclohexane 592. The system of claim 553, further comprising a linker, or hexane. wherein a first end of the linker is coupled to the nanopar 574. The system of claim 553, wherein the mixture further ticle, and wherein a Second end of the linker is coupled to the comprises a Solvent, and wherein the method further com receptor, and wherein the linker comprises a peptide prises removing entrained oxygen from the Solvent prior to mimetic. heating the mixture. 593. The system of claim 553, wherein the analyte com 575. The system of claim 553, wherein heating the prises a metal ion. mixture comprises heating the organometallic precursor and 594. The system of claim 553, wherein the analyte com the capping agent at a temperature equal to or greater than prises a phosphate functional groups. the Supercritical temperature of the capping agent. 595. The system of claim 553, wherein the analyte com 576. The system of claim 553, wherein heating the prises a bacterium. mixture comprises heating the organometallic precursor and 596. The system of claim 553, wherein the analyte com the capping agent at a temperature and pressure Such that the prises a protease. capping agent is in a Supercritical State. 597. The system of claim 553, wherein the analyte com 577. The system of claim 553, wherein the mixture further prises a nuclease. comprises a Solvent, and wherein heating the mixture com 598. A system for electrically communicating with a prises heating the organometallic precursor, the capping biological entity comprising: agent, and the Solvent at a temperature equal to or greater a nanoparticle, comprising a metal and a capping agent than the Supercritical temperature of the Solvent. coupled to the metal, wherein at least one of the 578. The system of claim 553, wherein the mixture further nanoparticles have an average particle diameter of comprises a Solvent, and wherein heating the mixture com between about 1 to about 100 angstroms, and wherein prises heating the organometallic precursor, the capping the capping agent inhibits oxidation of the nanopar agent, and the Solvent at a temperature and pressure Such ticles, and wherein at least one of the nanoparticles that the Solvent is in a Supercritical State. produces an electric field in response to a Stimulus, and 579. The system of claim 553, wherein the method further a receptor configured to interact with the biological entity, comprised removing the formed nanoparticles from the wherein the receptor is coupled to the nanoparticle. unreacted organometallic precursor and capping agent after heating the mixture. k k k k k