US 2010O283 005A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2010/0283005 A1 Pickett et al. (43) Pub. Date: Nov. 11, 2010

(54) NANOPARTICLES AND THEIR Publication Classification MANUFACTURE (51) Int. Cl. (75) Inventors: Nigel Pickett, London (GB); C09K II/70 (2006.01) Steven Daniels, Manchester (GB); C09K II/62 (2006.01) Imrana Mushtaq, Manchester C09K II/56 (2006.01) (GB) s C09K II/54 (2006.01) HOIL 3.3/04 (2010.01) Correspondence Address: HOIL 2L/20 (2006.01) GOODWIN PROCTER LLP (52) U.S. Cl...... 252/301.6 S; 252/301.6 P; 252/301.4 P: PATENT ADMINISTRATOR 252/301.6 R; 257/13:438/104;977/773; 53 STATE STREET, EXCHANGE PLACE 977/774; 257/E33.005; 257/E21.09 BOSTON, MA 02109-2881 (US) (73) Assignee: NANOCOTECHNOLOGIES (57)57 ABSTRACT LIMITED, Manchester (GB) Nanoparticles include or consist essentially of (i) a core that itself includes or consists essentially of a first material, and (21) Appl. No.: 12/239,254 (ii) a layer including or consisting essentially of a second material. In various embodiments, one of the first and second (22) Filed: Sep. 26, 2008 materials is a semiconductor material incorporating ions from O O group 13 and group 15 of the periodic table, and the other of Related U.S. Application Data the first and second materials is a metal oxide material incor (60) Provisional application No. 60/980.946, filed on Oct. porating metal ions selected from any one of groups 1 to 12, 18, 2007. 14 and 15 of the periodic table. In other embodiments, one of s the first and second materials is a semiconductor material, and (30) Foreign Application Priority Data the other of the first and second materials is an oxide of a metal selected from any one of groups 3 to 10 of the periodic Sep. 28, 2007 (GB) ...... O719073.9 table. Methods for preparing Such nanoparticles are also Sep. 28, 2007 (GB) ...... O719075.4 described.

Patent Application Publication Nov. 11, 2010 Sheet 1 of 5 US 2010/0283005 A1

HYDROCARBON CHAIN Patent Application Publication Nov. 11, 2010 Sheet 2 of 5 US 2010/0283005 A1

s - - y n -ZnO - N.

n > -

se f w

f y w - ?. - / f as s

Fe2O3

FIG. 4 Patent Application Publication Nov. 11, 2010 Sheet 3 of 5 US 2010/0283005 A1

700000

6OOOOO InPlln2O3 5 O O O O O

4OOOOO

3OOOOO

2OOOOO

OOOOO

O m 350 450 550 650 750 850 950 WAVELENGTH(nm)

FIG. 5 Patent Application Publication Nov. 11, 2010 Sheet 4 of 5 US 2010/0283005 A1

400 450 500 550 600 650 700 WAVELENGTH(nm)

FIG. 6 Patent Application Publication Nov. 11, 2010 Sheet 5 of 5 US 2010/0283005 A1

CdSely-Fe2O3

CdSe

20 30 40 50 60 70 2-theta (degrees)

FIG. 7 US 2010/0283005 A1 Nov. 11, 2010

NANOPARTICLES AND THEIR responding macrocrystalline material and consequently the MANUFACTURE first excitonic transition (band-gap) increases in energy with decreasing particle diameter. CROSS-REFERENCE TO RELATED 0006 Single-core semiconductor nanoparticles, which APPLICATIONS involve a single semiconductor material along with an outer organic passivating layer, may have relatively low quantum 0001. This application claims priority to and the benefit of and incorporates herein by reference in their entireties, U.S. efficiencies due to electron-hole recombination occurring at Provisional Patent Application No. 60/980.946, filed on Oct. defects and dangling bonds situated on the nanoparticle Sur 18, 2007; U.K. Patent Application No. 0719073.9, filed on face (which lead to non-radiative electron-hole recombina Sep. 28, 2007; and U.K. Patent Application No. 0719075.4, tions). filed on Sep. 28, 2007. 0007. One method to eliminate defects and dangling bonds is to grow a second inorganic material, having a wider band-gap and Small lattice mismatch to that of the core mate FIELD OF THE INVENTION rial, epitaxially on the Surface of the core particle to produce 0002 The present invention relates to semiconductor a “core-shell' particle. Core-shell particles separate any car nanoparticles and techniques for their production. riers confined in the core from surface states that would otherwise act as non-radiative recombination centres. One example is ZnS grown on the surface of a CdSe core to BACKGROUND provide a CdSe/ZnS core/shell nanoparticle. 0003. There has been substantial interest in the prepara 0008 Another approach is to prepare a core/multi-shell tion and characterisation of compound semiconductors com structure where the “electron-hole' pair is completely con prising particles with dimensions, for example in the range fined to a single shell layer Such as the quantum dot-quantum 2-50 nm, often referred to as 'quantum dots or nanocrystals. well structure. Here, the core is of a wide bandgap material, These studies have occurred mainly due to the size-tuneable followed by a thin shell of narrower bandgap material, and electronic properties of these materials that may be exploited capped with a further wide bandgap layer, such as CdS/HgS/ in many commercial applications such as optical and elec CdS grown using a substitution of Hg for Cd on the surface of tronic devices and other applications that now range from the core nanocrystal to depositjust a few monolayers of HgS. biological labelling, Solar cells, catalysis, biological imaging, The resulting structures exhibited clear confinement of light-emitting diodes, general space lighting and both elec photo-excited carriers in the HgSlayer. troluminescence and photoluminescence displays amongst 0009. The coordination about the final inorganic surface many new and emerging applications. atoms in any core, core-shell or core-multi shell nanoparticle 0004. The most studied of semiconductor materials have is generally incomplete, with highly reactive atoms that are been the chalcogenide II-VI (i.e., group 12-group 16 of the not fully coordinated leaving "dangling bonds on the Surface periodic table) materials, such as ZnS, ZnSe, CdS, CdSe and of the particle, which may lead to particle agglomeration. CdTe. CdSe has been greatly studied due to its optical tune This problem is overcome bypassivating (capping) the "bare ability over the visible region of the spectrum. Although some Surface atoms with protecting organic groups. earlier examples appear in the literature, more recently, repro 0010. The outermost layer (capping agent) of organic ducible methods have been developed from “bottom up' material or sheath material helps to inhibit particle aggrega techniques, whereby particles are prepared atom-by-atom tion and also further protects the nanoparticle from its Sur using 'wet' chemical procedures. rounding chemical environment. It also provides chemical 0005. Two fundamental factors, both related to the size of linkage to other inorganic, organic or biological material. In the individual semiconductor nanoparticle, are responsible many cases, the capping agent is the solvent in which the for the unique properties of these particles. The first is the nanoparticle preparation is undertaken, and may be a Lewis large Surface-to-volume ratio: as a particle becomes Smaller, base compound, or a Lewis base compound diluted in an inert the ratio of the number of surface atoms to those in the interior Solvent, such as a hydrocarbon, whereby a lone pair of elec increases. This leads to the Surface properties playing an trons are capable of donor-type coordination to the Surface of important role in the overall properties of the material. The the nanoparticle. second factor is that, with semiconductor nanoparticles, there 0011 Important issues concerning the synthesis of high is a change in the electronic properties of the material with quality semiconductor nanoparticles include particle unifor size; for example, the band-gap gradually becomes larger mity, size distribution, quantum efficiencies, and, for com because of quantum confinement effects as the size of the mercial applications, long-term chemical and photostability. particles decreases. This effect gives rise to discrete energy Early routes applied conventional colloidal aqueous chemis levels similar to those observed in atoms and molecules, try, with more recent methods involving the kinetically con rather than a continuous band as in the corresponding bulk trolled precipitation of nanocrystallites, using organometallic semiconductor material. Thus, for a semiconductor nanopar compounds. Most of the more recent methods are based on ticle, because of the physical parameters, the “electron and the original “nucleation and growth' method described by hole', produced by the absorption of electromagnetic radia Murray et al., J. Am. Chem. Soc. 115:8706 (1993) (hereafter tion (a photon) with energy greater then the first excitonic “Murray et al.”), the entire disclosure of which is incorporated transition, are closer together than in the corresponding mac by reference herein, but use other precursors from that of the rocrystalline material, so that the Coulombic interaction can organometallic ones originally used, such as oxides (e.g., not be neglected. This leads to a narrow bandwidth emission, CdO), carbonates (e.g., MCO), acetates (e.g., M(CHCO)) which is dependent upon the particle size and composition. and acetylacetanates (e.g., MICHCOOCH=C(C )CH) Thus, quantum dots have higher kinetic energy than the cor in which, for example, M=Cd or Zn. US 2010/0283005 A1 Nov. 11, 2010

0012 Murray et al. originally used organometallic solu (0016 Strouse et al., Chem. Mater. 14:1576 (2002) (here tions of metal-alkyls (RM) where M-Cd, Zn, Te: R=Me, Et after “Strouse et al.”), the entire disclosure of which is incor and tri-n-octylphosphine sulfide/selenide (TOPS/Se) dis porated by reference herein, used a similar synthetic approach solved in tri-n-octylphosphine (TOP). These precursor solu using II-VI clusters to grow II-VI nanoparticles, but tions are injected into hot tri-n-octylphosphine oxide (TOPO) employed thermolysis (lyothermal) rather than a chemical in the temperature range 120-400° C. depending on the mate agent to initiate particle growth. Moreover, the single-source rial being produced. This produces TOPO-coated/capped precursors (IMoSea (SPh) X where X—Li' or (CH) semiconductor nanoparticles of II-VI material. The size of the NH", and M=Cd or Zn) were thermolysised, whereby frag particles is controlled by the temperature, capping agent, mentation of some clusters occurred followed by particle concentration of precursor used and the length of time at growth from Scavenging of the free M and Se ions, or simply which the synthesis is undertaken, with larger particles being from clusters aggregating together to form, initially, larger obtained at higher temperatures, higher precursor concentra clusters, then Small nanoparticles, and ultimately, larger tions and prolonged reaction times. This organometallic route nanoparticles. has advantages, including greater monodispersity and high 0017. Both of the Cooney et al. and Strouse et al. methods particle cystallinity, over other synthetic methods. As men employed molecular clusters to grow nanoparticles, but used tioned, many variations of this method have now appeared in ions from the clusters to grow the larger nanoparticles— the literature and routinely give good-quality (interms of both either by fragmentation of Some clusters or cluster aggrega monodispersity and quantum yield) core and core-shell nano tion. In neither case was a separate nanoparticle precursor particles. composition used to provide the ions required to grow the 0013 Single-source precursors have also proven useful in larger nanoparticle on the original molecular cluster. More the synthesis of semiconductor nanoparticle materials of II over, neither of these approaches retained the structural integ VI, as well as other, compound semiconductor nanoparticles. rity of the original individual molecular clusters in the final Bis(dialkyldithio-fcdiseleno-carbamato)cadmium(II)/zinc(II) nanoparticles. Furthermore, it may be seen that both of these compounds, M(ECNR) (where M-Zn or Cd, E=S or Se methods are limited to forming a II-VI nanoparticle using a and R-alkyl), have been used in a similar one-pot synthetic II-VI cluster, which is an inevitable consequence of using the procedure, which involved dissolving the precursor in TOP material of the molecular clusters to build the larger nanopar followed by rapid injection into hot tri-n-octylphosphine ticles. This prior work is therefore limited in terms of the oxide/tri-n-octylphosphine (TOPO/TOP) above 200° C. range of possible materials that may be produced. 0014) Fundamentally, all of the above procedures rely on (0018 Published International Patent Application Nos. the principle of high-temperature particle nucleation, fol PCT/GB2005/001611 and PCT/GB2006/004003, the entire lowed by particle growth at a lower temperature. Moreover, to disclosures of which are incorporated by reference herein, provide a monodispersed ensemble of nanoparticles in the describe methods of producing large Volumes of high-quality 2-10 nm range, generally there is proper separation of nano mono-dispersed quantum dots, which overcome many of the particle nucleation from nanoparticle growth. This is problems associated with earlier Small-scale methods. achieved by rapid injection of a cooler solution of one or both Chemical precursors are provided in the presence of a precursors into a hotter coordinating solvent (containing the molecular cluster compound under conditions whereby the other precursor if otherwise not present), which initiates par integrity of the molecular cluster is maintained and in that ticle nucleation. The sudden addition of the cooler solution way acts as a well-defined prefabricated seed or template to upon injection Subsequently lowers the reaction temperature provide nucleation centres that react with the chemical pre (the volume of solution added is typically about/3 of the total cursors to produce high quality nanoparticles on a Sufficiently solution) and inhibits further nucleation. Particle growth (be large scale for industrial application. ing a Surface-catalyzed process or via Ostwald ripening 0019. An important distinguishing feature of the methods depending on the precursors used) continues to occur at the described in PCT/GB2005/OO1611 and PCT/GB2006/ lower temperature, thus nucleation and growth are separated 004003 is that conversion of the precursor composition to the which yields a narrow nanoparticle size distribution. This nanoparticles is effected in the presence of a molecular cluster method works well for small-scale synthesis where one solu compound which retains its structural integrity throughout tion may be added rapidly to another while keeping a reason nanoparticle growth. Identical molecules of the cluster com ably homogeneous temperature throughout the reaction. pound act as seeds or nucleation points upon which nanopar However, on the larger preparative scales needed for com ticle growth is initiated. In this way, a high temperature nucle mercial applications, whereby large Volumes of Solution are ation step is not necessary to initiate nanoparticle growth required to be rapidly injected into one another, a significant because suitable well-defined nucleation sites are already temperature differential may occur within the reaction mix provided in the system by the molecular clusters. The mol ture, and this may Subsequently lead to an unacceptably large ecules of the cluster compound act as a template to direct particle size distribution. nanoparticle growth. Molecular cluster is a term widely 0015 Cooney et al., J. Mater. Chem. 7(4):647 (1997) understood in the relevant technical field, but for the sake of (hereafter “Cooney et al.”), the entire disclosure of which is clarity, it should be understood herein to relate to clusters of incorporated by reference herein, used a II-VI molecular clus three or more metal atoms and their associated ligands of ter, SCdo (SPh), MeNHL to produce II-VI nanopar sufficiently well defined chemical structure such that all mol ticles of CdS, which also involved the oxidation of surface ecules of the cluster compound possess the same relative capping SPh ligands by iodine. This preparative route molecular formula. Thus the molecular clusters are identical involved the fragmentation of the majority of the II-VI clus to one another in the same way that one H2O molecule is ters into ions, which were consumed by the remaining II-VI identical to another HO molecule. By providing nucleation (ISCdo (SPh).") clusters that subsequently grew into II sites which are so much more well defined than the nucleation VI nanoparticles of CdS. sites employed in earlier methods, the use of the molecular US 2010/0283005 A1 Nov. 11, 2010 cluster compound may provide a population of nanoparticles have additional properties that are desirable or required in that are essentially monodispersed. A further significant many commercial applications such as paramagnetism. advantage of this method is that it may be more easily scaled 0027. The semiconductor material, e.g., the III-V semi up. conductor material, and metal oxide material may be pro 0020. There is great interest in bi-functional and multi vided in any desirable arrangement, e.g., the nanoparticle functional nano-scale materials. While a few examples of core material may comprise the metal oxide material and one Such materials are known, Such as nanoparticles of different or more shells or layers of material grown on the core may compositions fused together to form heterostructures of inter comprise the semiconductor material, e.g., the III-V semicon linked nanoparticles (see FIG. 1), there are still relatively few ductor material. Alternatively, the nanoparticle core may reports of the successful fabrication and exploitation of such comprise the semiconductor material, e.g., the III-V semicon materials. ductor material, and the outer shell or at least one of the outer shells (where more than one is provided) may comprise the SUMMARY metal oxide material. 0028. In an embodiment, the first material is the III-V 0021 Anaim of an embodiment of the present invention is semiconductor material and the second material is the oxide to provide nanoparticle materials exhibiting increased func of a metal from any one of groups 1 to 12, 14 and 15 of the tionality. A further aim of an embodiment of the present periodic table. The metal oxide material may be provided as invention is to provide nanoparticles that are more robust a layer between an inner inorganic core comprising or con and/or exhibit enhanced optical properties. sisting essentially of the III-V semiconductor material and an 0022. In a first aspect, the invention provides a nanopar outermost organic capping layer. ticle comprising a core that itself comprises a first material 0029. In another embodiment, the first material is the and a layer comprising a second material, wherein one of the semiconductor material and the second material is the oxide first and second materials is a semiconductor material incor of a metal selected from groups 3 to 10 of the periodic table. porating ions from group 13 and group 15 of the periodic table The metal oxide material may be provided as a layer between and the other of the first and second materials is a metal oxide an inner inorganic core or layer and an outermost organic material incorporating metal ions selected from any one of capping layer. groups 1 to 12, 14 and 15 of the periodic table. 0030. Any of a number of metal and metal oxide precur 0023. In a second aspect, the invention provides a method sors may be employed to form a shell comprising a metal for producing a nanoparticle comprising a core that itself oxide material, e.g., in which the metal is taken from any one comprises a first material and a layer comprising a second of groups 1 to 12, 14 and 15 of the periodic table, grown on a material, wherein one of the first and second materials is a semiconductor nanoparticle core or core/shell resulting in a semiconductor material incorporating ions from group 13 and quantum dot/metal oxide core/shell nanoparticle, a quantum group 15 of the periodic table and the other of the first and dot inorganic core and shell provided with an outer metal second materials is a metal oxide material incorporating oxide layer, or a core/multi-shell quantum dot provided with metal ions selected from any one of groups 1 to 12, 14 and 15 an outer metal oxide shell. The outer metal oxide layer may of the periodic table, the method comprising forming the core enhance the photostability and chemical stability of the nano and forming (e.g., depositing) the layer comprising the sec particle and may therefore render the nanoparticle resistant to ond material. fluorescence quenching and/or its Surrounding chemical 0024. In a third aspect, the invention provides a nanopar environment. Through use of an oxide as the outer layer, if the ticle comprising a core that itself comprises a first material nanoparticles reside in an oxygen-containing environment, and a layer comprising of a second material, wherein one of very little or no further oxidation typically occurs. the first and second materials is a semiconductor material and 0031. In various embodiments of the present invention the other of the first and second materials is an oxide of a there are provided core/shell and core/shell/shell nanopar metal selected from any one of groups 3 to 10 of the periodic ticles comprising a quantum dot core and metal oxide shell or table. a quantum dot core/shell structure with an outer metal oxide 0025. In a fourth aspect, the invention provides a method shell. In some preferred embodiments of the present invention for producing a nanoparticle comprising a core that itself there are provided core/shell and core/shell/shell nanopar comprises a first material and a layer comprising a second ticles comprising a quantum dot core and metal oxide shell, in material, wherein one of the first and second materials is a which the metal is taken from any one of groups 1 to 12, 14 semiconductor material and the other of the first and second and 15 of the periodic table, or a quantum dot core/shell materials is an oxide of a metal selected from any one of structure with an outer metal oxide shell, in which the metal groups 3 to 10 of the periodic table, the method comprising is taken from any one of groups 1 to 12, 14 and 15 of the forming the core and forming (e.g., depositing) the layer periodic table. The combination of the luminescence of the comprising the second material. core and metal oxide shell are well-suited to applications such 0026. These aspects of the invention provide semiconduc as biological, displays, lighting, Solarcells and contrast imag tor/metal oxide core/shell quantum dots and related materi ing. The preparation of core/shell semiconductor nanopar als, and methods for producing the same. Embodiments of the ticles with an outer layer of metal oxide, e.g., in which the invention provide semiconductor-metal oxide nanoparticle metal is taken from any one of groups 1 to 12, 14 and 15 of the materials, and include compound semiconductor particles periodic table, improves the luminescent properties of the otherwise referred to as quantum dots or nanocrystals, within semiconductor core material and makes them more stable the size range 2-100 nm. The nanoparticle materials accord against their surrounding chemical environment, i.e., reduces ing to the first aspect of the present invention may be more photo-oxidation at the surface or interface of the materials. robust than non-metal-oxide-containing nanoparticles to This enhanced Stability is important for many commercial their surrounding chemical environment, and in Some cases applications. There is also the added desirability of the par US 2010/0283005 A1 Nov. 11, 2010

ticles being bi-functionalm, i.e., having both luminescence precursor composition comprises separate first and second and paramagnetic properties, in some cases. core precursor species containing the ions to be incorporated 0032. With regard to the method of forming, formation of into the growing nanoparticle core. The conversion is effected the core may comprise effecting conversion of a nanoparticle in the presence of a molecular cluster compound under con core precursor composition to the material of the nanoparticle ditions permitting seeding and growth of the nanoparticle core. The nanoparticle core precursor composition preferably COC. comprises first and second core precursor species containing 0039 Formation of the layer comprising the second mate the ions to be incorporated into the growing nanoparticle rial preferably comprises effecting conversion of a second COC. material precursor composition to the second material. It is 0033. The first and second core precursor species may be preferred that the second material precursor composition separate entities contained in the core precursor composition, comprise third and fourth ions to be incorporated into the and conversion may be effected in the presence of a molecular layer comprising the second material. The third and fourth cluster compound under conditions permitting seeding and ions may be separate entities contained in the second material growth of the nanoparticle core. precursor composition, or the third and fourth ions may be 0034. The first and second core precursor species may be combined in a single entity contained in the second material combined in a single entity contained in the core precursor precursor composition. composition. The semiconductor material may incorporate 0040. The first material may be the semiconductor mate ions selected from at least one of groups 2 to 16 of the periodic rial incorporating ions from groups 13 and 15 of the periodic table. table and the second material may be the metal oxide. The 0035. Formation of the layer comprising the second mate second material precursor composition may comprise the rial preferably comprises effecting conversion of a second metalions and the oxide ions to be incorporated into the layer material precursor composition to the second material. The comprising the metal oxide. In various embodiments the sec second material precursor composition may comprise third ond material precursor composition contains a metal car and fourth ions to be incorporated into the layer comprising boxylate compound comprising metalions to be incorporated the second material. The third and fourth ions may be separate into the layer comprising the metal oxide material and the entities contained in the second material precursor composi conversion comprises reacting the metal carboxylate com tion, or may be combined in a single entity contained in the pound with an alcohol compound. second material precursor composition. 0041. In a sixth aspect, the invention provides a method for 0036. In some embodiments, the first material is the semi producing a nanoparticle comprising a core comprising a conductor material and the second material is the metal oxide. semiconductor material incorporating ions from group 13 and The second material precursor composition may comprise the group 15 of the periodic table and a layer comprising a metal metalions and the oxide ions to be incorporated into the layer oxide material. The method comprises forming the core and comprising the metal oxide. The second material precursor then forming the layer by effecting conversion of a metal composition may contain a molecular complex comprising oxide precursor composition to the metal oxide material. The metal cations and N-nitrosophenylhydroxylamine anions. metal oxide precursor composition contains a metal carboxy The metal may be selected from group 8 (VIII) of the periodic late compound comprising metalions to be incorporated into table, e.g., iron. the layer comprising the metal oxide and the conversion com 0037. In some other embodiments, the first material is the prises reacting the metal carboxylate compound with an alco semiconductor material incorporating ions from groups 13 hol compound. and 15 of the periodic table and the second material is the 0042. The metal oxide precursor composition comprises metal oxide, in which the metal is taken from any one of oxide ions to be incorporated into the layer comprising the groups 1 to 12, 14 and 15 of the periodic table. The second metal oxide. The oxide ions may be derived from the metal material precursor composition may comprise the metal ions carboxylate compound, or alternatively, from a source other and the oxide ions to be incorporated into the layer compris than the metal carboxylate compound. ing the metal oxide. The second material precursor composi 0043. Formation of the core may comprise effecting con tion may contain a metal carboxylate compound comprising version of a nanoparticle core precursor composition to the metal ions to be incorporated into the layer comprising the material of the nanoparticle core. The nanoparticle core pre metal oxide material and the conversion may comprise react cursor composition may comprise first and second core pre ing the metal carboxylate compound with an alcohol com cursor species containing the group 13 ions and group 15 ions pound. The metal may be selected from group 8 (VIII) of the to be incorporated into the growing nanoparticle core. The periodic table, and may, for example, be iron. In some first and second core precursor species may be separate enti embodiments the metal is selected from group 12 (IIB) of the ties contained in the core precursor composition, and the periodic table, e.g., zinc. conversion may be effected in the presence of a molecular 0038. In a fifth aspect, the invention provides a method for cluster compound under conditions permitting seeding and the production of a nanoparticle comprising a core that itself growth of the nanoparticle core. Alternatively, the first and comprises a first material and a layer comprising a second second core precursor species may be combined in a single material, wherein one of the first and second materials is a entity contained in the core precursor composition. semiconductor material incorporating ions from group 13 and 0044) The carboxylate moiety of the metal carboxylate group 15 of the periodic table and the other of the first and compound may comprise 2 to 6 carbonatoms, and may be, for second materials is a metal oxide material. The method com example, a metal acetate compound. The alcohol may be a prises forming the core and forming the layer comprising the C-C linear or branched alcohol compound, more prefer second material, wherein formation of the core comprises ably a linear Saturated C-C alcohol, and most preferably effecting conversion of a nanoparticle core precursor compo an alcohol selected from the group consisting of 1-heptade sition to the material of the nanoparticle core, and the core canol, 1-octadecanol and 1-nonadecanol. In various embodi US 2010/0283005 A1 Nov. 11, 2010 ments the reaction of the metal carboxylate compound and used, it will usually be used in the presence of a further the alcohol yields the metal oxide material of the nanoparticle coordinating agent to act as a capping agent. This is because, layer. if the nanoparticles being formed are intended to function as 0045. With regard to the second, fifth and sixth aspects of quantum dots, it is important that the Surface atoms which are the invention, the metal may be selected from group 8 of the not fully coordinated “dangling bonds' are capped to mini periodic table, in which case the metal may be iron, or the mise non-radiative electron-hole recombinations and inhibit metal may be selected from group 12 of the periodic table, in particle agglomeration, which may lower quantum efficien which case it may be zinc. cies or form aggregates of nanoparticles. A number of differ 0046. In one embodiment a seeding II-VI molecular clus ent coordinating solvents are known which may also act as teris placed in a solvent (coordinating or non-coordinating) in capping or passivating agents, e.g., TOP TOPO, had or long the presence of nanoparticle precursors to initiate particle chain organic acids such as myristic acid (tetradecanoic acid), growth. The seeding molecular cluster is employed as a tem long chainamines (as depicted in FIG.2), functionalised PEG plate to initiate particle growth from other precursors present (polyethylene glycol) chains but not restricted to these cap within the reaction solution. The molecular cluster to be used ping agents. as the seeding agent may either be prefabricated or produced 0050. If a solvent that cannot act as a capping agent is in-situ prior to acting as a seeding agent. Some precursor may chosen, then any desirable capping agent may be added to the or may not be present at the beginning of the reaction process reaction mixture during nanoparticle growth. Such capping along with the molecular cluster, however, as the reaction agents are typically Lewis bases, including mono- or multi proceeds and the temperature is increased, additional dentate ligands of the type phosphines (trioctylphosphine, amounts of precursors may be added periodically to the reac triphenolphosphine, t-butylphosphine), phosphine oxides tion either dropwise as a solution or as a solid. (trioctylphosphine oxide), alkyl phosphonic acids, alkyl 0047. In accordance with various methods described amines (e.g., hexadecylamine, octylamine (see FIG. 2)), aryl herein, a nanoparticle precursor composition is converted to a amines, pyridines, octanethiol, a long chain fatty acid and desired nanoparticle. Suitable precursors include single thiophenes, but a wide range of other agents are available, Source precursors in which the two or more ions to be incor Such as oleic acid and organic polymers which form protec porated in to the growing nanoparticle, or multi-source pre tive sheaths around the nanoparticles. With reference to FIG. cursors having two or more separate precursors each of which 2 in which a tertiary amine containing higher alkyl groups is contains at least one ion to be included in the growing nano depicted, the amine head groups generally have a strong particle. The total amount of precursor composition required affinity for the nanocrystals and the hydrocarbon chains help to form the final desired yield of nanoparticles may be added to solubilise and disperse the nanocrystals in the solvent. before nanoparticle growth has begun, or alternatively, the 0051. The outermost layer (capping agent) of a quantum precursor composition may be added in stages throughout the dot may also comprise or consist essentially of a coordinated reaction. ligand that possesses additional functional groups that may be 0048. The conversion of the precursor to the material of used as chemical linkage to other inorganic, organic or bio the nanoparticles may be conducted in any Suitable solvent. It logical material, whereby the functional group points away will be appreciated that it is typically important to maintain from the quantum dot Surface and is available to bond/react the integrity of the molecules of the cluster compound. Con with otheravailable molecules, such as, for example, primary, sequently, when the cluster compound and nanoparticle pre secondary amines, alcohols, carboxylic acids, azides, cursor are introduced into the solvent, the temperature of the hydroxyl group. The outermost layer (capping agent) of a Solvent is generally sufficiently high to ensure satisfactory quantum dot may also comprise or consist essentially of a dissolution and mixing of the cluster compound—it is not coordinated ligand that possesses a functional group that is necessary that the present compounds are fully dissolved but polymerisable and may be used to form a polymer around the desirable—but not so high as to disrupt the integrity of the particle. cluster compound molecules. Once the cluster compound and 0052 The outermost layer (capping agent) may also com precursor composition are sufficiently well dissolved in the prise or consist essentially of organic units that are directly solvent, the temperature of the solution thus formed is raised bonded to the outermost inorganic layer and may also possess to a temperature, or range of temperatures, which is/are Suf a functional group, not bonded to the Surface of the particle, ficiently high to initiate nanoparticle growth but not so high as that may be used to form a polymer around the particle, or for to damage the integrity of the cluster compound molecules. further reactions. As the temperature is increased, further quantities of precur 0053. The first aspect of the invention concerns semicon sor are added to the reaction in a dropwise manner or as a ductor nanoparticles incorporating a III-V semiconductor solid. The temperature of the solution may then be maintained material and a metal oxide material, in which the metal is at this temperature or within this temperature range for as taken from any one of groups 1 to 12, 14 and 15 of the periodic long as required to form nanoparticles possessing the desired table. It will be appreciated that the methods representing the properties. fifth and sixth aspects of the present invention are directed to 0049. A wide range of appropriate solvents is available. forming nanoparticles incorporating a III-V semiconductor The particular solvent used is usually at least partly dependent material and any type of metal oxide material. In one method upon the nature of the reacting species, i.e., the nanoparticle for producing the nanoparticles, molecular clusters, for precursor and/or cluster compound, and/or the type of nano example, II-VI molecular clusters may be employed in, e.g., particles to be formed. Typical solvents include Lewis base the methods representing the second, fifth and sixth aspects of type coordinating solvents, such as a phosphine (e.g., TOP), a the invention, whereby the clusters are well defined identical phosphine oxide (e.g., TOPO) an amine (e.g., HDA), a thiol molecular entities, as compared to ensembles of Small nano Such as octanethiol or non-coordinating organic solvents, particles, which inherently lack the anonymous nature of e.g., alkanes and alkenes. If a non-coordinating solvent is molecular clusters. II-VI molecular clusters may be used to US 2010/0283005 A1 Nov. 11, 2010

grow cores comprising II-VI or non-II-VI semiconductor consisting essentially of the second material. The third mate materials (e.g., III-V materials, such as InP) as there is a large rial may be a semiconductor material incorporating ions number of II-VI molecular clusters that may be made by selected from at least one of groups 2-16 of the periodic table. simple procedures and which are not air and moisture sensi 0060. In another aspect, embodiments of the invention tive, as is typically the case with III-V clusters. Use of a feature a method for producing a nanoparticle that includes a molecular cluster typically obviates the need for a high-tem core that includes or consists essentially of a first material perature nucleation step as in the conventional methods of and, thereover, a layer that includes or consists essentially of producing quantum dots, which means large-scale synthesis a second material. One of the first and second materials is a is possible. semiconductor material incorporating ions from group 13 and 0054 Moreover, it is possible to use a II-VI molecular group 15 of the periodic table and the other of the first and cluster, such as HNEtaZnS,(SPh), to seed the growth second materials is a metal oxide material incorporating of III-V nanoparticle materials such as InP and GaP quantum metalions selected from any one of groups 1 to 12, 14 and 15 dots and their alloys. Following addition or formation in situ of the periodic table. The method includes forming the core of the II-VI molecular cluster, molecular sources of the III and and, thereover, forming the layer including or consisting V ion (i.e., "molecular feedstocks”) are added and consumed essentially of the second material. to facilitate particle growth. These molecular sources may be 0061 Formation of the core may include (i) effecting con periodically added to the reaction Solution so as to keep the version of a nanoparticle core precursor composition to the concentration of free ions to a minimum whilst maintaining a composition of the nanoparticle core, and (ii) growing the concentration of free ions to inhibit Ostwald's ripening from core. The precursor composition may include or consist occurring and defocusing of nanoparticle size range from essentially of first and second core precursor species contain occurring. ing ions to be incorporated into the growing nanoparticle 0055 Nanoparticle growth may be initiated by heating core. The first and second core precursor species may be (thermolysis) or by solvothermal means. The term solvother separate entities in the core precursor composition, and the mal is used herein to refer to heating in a reaction solution so conversion may be effected in the presence of a molecular as to initiate and Sustain particle growth, and is intended to cluster compound under conditions permitting seeding and encompass the processes which are also sometimes referred growth of the nanoparticle core. The first and second core to as thermolsolvol. Solution-pyrolysis, and lyothermal. Par precursor species may be combined in a single entity con ticle preparation may also be accomplished by a chemical tained in the core precursor composition. reaction, i.e., by changing the reaction conditions, such as 0062 Formation of the layer including or consisting adding a base or an acid, elevation of pressures, i.e., using essentially of the second material may include effecting con pressures greater than atmospheric pressure, application of version of a second material precursor composition to the electromagnetic radiation, such as microwave radiation or second material. The second material precursor composition any one of a number of other methods known to the skilled may include or consist essentially of third and fourth ions to person. be incorporated into the layer including or consisting essen 0056. Once the desired nanoparticle cores are formed, at tially of the second material. The third and fourth ions may be least one shell layer is grown on the Surface of each core to separate entities contained in the second material precursor provide the nanoparticles. Alternatively, once the desired composition, or may be combined in a single entity contained nanoparticle cores are formed, at least one shell layer may be in the second material precursor composition. grown on the Surface of each core. Any suitable method may 0063. The first material may be the semiconductor mate be employed to provide the shell layer(s). rial incorporating ions from groups 13 and 15 of the periodic 0057. In an aspect, embodiments of the invention feature a table and the second material may be the metal oxide. The nanoparticle including a core that includes or consists essen second material precursor composition may include or con tially of a first material and, thereover, a layer that includes or sist essentially of the metal ions and the oxide ions to be consists essentially of a second material. One of the first and incorporated into the layer including or consisting essentially second materials is a semiconductor material incorporating of the metal oxide. The second material precursor composi ions from group 13 and group 15 of the periodic table, and the tion may include or consist essentially of a metal carboxylate other of the first and second materials is a metal oxide mate compound comprising metal ions to be incorporated into the rial incorporating metalions selected from any of groups 1-15 layer including or consisting essentially of the metal oxide of the periodic table. The metal oxide material may incorpo material, and the conversion may include or consist essen rate metal ions selected from any of groups 1-12, 14, and 15 tially of reacting the metal carboxylate compound with an of the periodic table. The metalions may comprise or consist alcohol compound. essentially of iron, and the resulting iron oxide may have a 0064. The metal may be selected from group 8 of the formula selected from the group consisting of FeC), Fe2O, periodic table, and may include or consist essentially of iron. and FeO. The iron oxide may bey-Fe2O. The first material The metal may be selected from group 12 of the periodic may be the semiconductor material and the second material table, and may include or consist essentially of zinc. may be the metal oxide material. 0065. In yet another aspect, embodiments of the invention 0058. The group 13 ions incorporated in the semiconduc feature a nanoparticle including or consisting essentially of a tor material may be selected from the group consisting of core that includes or consists essentially of a first material, boron, aluminium, gallium, and indium. The group 15 ions and, thereover, a layer that includes or consists essentially of incorporated in the semiconductor material may be selected a second material. One of the first and second materials is a from the group consisting of phosphide, arsenide, and nitride. semiconductor material, and the other of the first and second 0059. The nanoparticle may include a layer comprising or materials is a metal oxide material incorporating metal ions consisting essentially of a third material, the layer disposed selected from any one of groups 1-12, 14, and 15 of the between the nanoparticle core and the layer comprising or periodic table. The metal may be selected from any of groups US 2010/0283005 A1 Nov. 11, 2010

5-10, 6-9, or 7-9 of the periodic table. The metal may be embodiments described herein are not mutually exclusive and selected from group 8 of the periodic table, and may be may exist in various combinations and permutations. selected from the group consisting of iron, ruthenium, and osmium. The metal may comprise or consist essentially of BRIEF DESCRIPTION OF FIGURES iron, and the iron oxide may have a formula selected from the 0071. In the drawings, like reference characters generally group consisting of Fe0, Fe2O, and Fe-O. The iron oxide refer to the same parts throughout the different views. Also, may be Y-Fe2O. the drawings are not necessarily to scale, emphasis instead 0066 Embodiments of the invention may feature one or generally being placed upon illustrating the principles of the more of the following. The semiconductor material may invention. In the following description, various embodiments incorporate ions selected from at least one of groups 2-16 of of the present invention are described with reference to the the periodic table. The ions may include or consistessentially following drawings, in which: of at least one member of the group consisting of magnesium, 0072 FIG. 1 is a schematic representation of a prior art calcium, and strontium. The ions may include or consist iron oxide core nanoparticle linked to a plurality of CdS essentially of at least one member of the group consisting of nanoparticles; 0073 FIG. 2 is a schematic representation of a nanopar Zinc, cadmium, and mercury. The ions may include or consist ticle coated with octylamine capping agent; essentially of at least one member of the group consisting of 0074 FIG. 3 is a schematic representation of a) a particle boron, aluminium, gallium, and indium. The ions may consisting of a semiconductor core only, b) a particle having include or consist essentially of at least one member of the a semiconductor core and metal-oxide shell in accordance group consisting of lead and tin. The ions may include or with a preferred embodiment of the present invention, and c) consist essentially of at least one member of the group con a particle having a semiconductor core, a buffer layer of a sisting of Sulfur, selenium, and tellurium. The ions may different semiconductor material and an outer metal-oxide include or consist essentially of at least one member of the shell in accordance with a further preferred embodiment of group consisting of phosphide, arsenide, and nitride. The ions the present invention; may include or consist essentially of carbide ions. 0075 FIG. 4 is a schematic representation of a semicon 0067. The semiconductor material may include or consist ductor/metal oxide (InP/FeO) core/shell nanoparticle essentially of ions selected from the group consisting of ions according to a preferred embodiment of the present invention from the transition metal group of the periodic table and ions prepared as described below in Example 3: from the d-block of the periodic table. The nanoparticle may 0076 FIG. 5 shows photoluminescence spectra of InP and include a layer including or consisting essentially of a third InP/InO nanoparticles produced according to Example 4; material disposed between the nanoparticle core and the layer 0077 FIG. 6 shows photoluminescence spectra of CdSe/ including or consisting essentially of the second material. The Y-Fe-O nanoparticles according to a further preferred first material may be the semiconductor material and the embodiment of the first aspect of the present invention with increasing Fe2O shell thickness prepared as described below second material may be the metal oxide. in Example 7; and 0068. In a further aspect, embodiments of the invention (0078 FIG. 7 shows X-ray diffraction patterns of the CdSe/ feature a method for producing a nanoparticle including or Y-Fe-O core/shell nanoparticles prepared according to consisting of a core that includes or consists essentially of a Example 7 (top line) and CdSe nanoparticles (bottom line); first material, and, thereover, a layer that includes or consists essentially of a second material. One of the first and second DETAILED DESCRIPTION materials is a semiconductor material, and the other of the first and second materials is an oxide of a metal selected from 007.9 Feedstocks any of groups 3-10 of the periodic table. The method includes 0080. These molecular feedstocks may be in the form of a forming the core and depositing, on the core, the layer includ single-source precursor whereby all elements required within ing or consisting essentially of the second material. the nanoparticle are present within a single compound pre cursor, or a combination of precursors each containing one or 0069. Formation of the core may include or consist essen more element/ion species required within the nanoparticles. tially of (i) effecting conversion of a nanoparticle core pre These feedstocks may be added at the beginning of the reac cursor composition to the composition of the nanoparticle tion or periodically throughout the reaction of particle core, and (ii) growing the core. The precursor composition growth, and may be in the form of liquids, solutions, Solids, may include or consist essentially of first and second core slurries or gases. precursor species containing ions to be incorporated into the I0081) Type of System to be Made growing nanoparticle core. The first and second core precur I0082 In some embodiments, the invention involves prepa Sor species may be separate entities in the core precursor ration of nanoparticulate materials incorporating a III-V composition, and the conversion may be effected in the pres semiconductor material (that is, a semiconductor material ence of a molecular cluster compound under conditions per incorporating ions from groups 13 and 15 of the periodic mitting seeding and growth of the nanoparticle core. The first table) and certain metal oxide materials, and includes com and second core precursor species may be combined in a pound semiconductor particles otherwise referred to as quan single entity contained in the core precursor composition. tum dots or nanocrystals within the size range 2-100 nm. 0070 These and other objects, along with advantages and I0083. The III-V semiconductor material may be in (or features of the present invention herein disclosed, will constitute) the core of the nanoparticle, or in one or more of become more apparent through reference to the following the outer shells or layers of material formed on the nanopar description, the accompanying drawings, and the claims. Fur ticle core. It is particularly preferred that the III-V material is thermore, it is to be understood that the features of the various in the nanoparticle core. The III-V semiconductor material US 2010/0283005 A1 Nov. 11, 2010 may incorporate group 13 ions selected from the group con als include but are not restricted to MgS, MgSe, MgTe, sisting of boron, aluminium, gallium and indium; and/or CaS, CaSe, CaTe, SrS, SrSe, SrTe. group 15 ions selected from the group consisting of phos 0090 IIB-VIB (12-16) material incorporating of a first phide, arsenide and nitride. element from group 12 of the periodic table and a second 0084. The same or a different semiconductor material may element from group 16 of the periodic table and also form one or more shell layers around the nanoparticle core, including ternary and quaternary materials and doped Subject to the proviso that the nanoparticle material also materials. Suitable nanoparticle semiconductor materi als include but are not restricted to ZnS, ZnSe, ZnTe, incorporates a material that is an oxide of a metal. CdS, CdSe, CdTe. HgS, HgSe, HgTe. 0085 Nanoparticles in accordance with the invention may 0.091 II-V material incorporating a first element from further comprise a non-III-V semiconductor material. The group 12 of the periodic table and a second element from non-III-V semiconductor material may incorporate ions group 15 of the periodic table and also including ternary selected from at least one of groups 2 to 16 of the periodic and quaternary materials and doped materials. Suitable table. The non-III-V semiconductor material may be used in nanoparticle semiconductor materials include but are one or more shells or layers grown on the nanoparticle core not restricted to Zn-P, ZnAS, CdP, CdAS Cd N, and in most cases will be of a similar lattice type to the Zn-N. material in the immediate inner layer upon which the non 0092. III-IV material incorporating a first element from III-V material is being grown, i.e., have close lattice match to group 13 of the periodic table and a second element from the immediate inner material so that the non-III-V material group 14 of the periodic table and also including ternary may be epitaxially grown, but is not necessarily restricted to and quaternary materials and doped materials. Suitable materials of this compatibility. nanoparticle semiconductor materials include but are I0086. The non-III-V semiconductor material may incor not restricted to B.C. AlC, GaC. porate ions from group 2 (IIA) of the periodic table, which 0.093 III-VI material incorporating a first element from may be selected from the group consisting of magnesium, group 13 of the periodic table and a second element from calcium and strontium. The non-III-V semiconductor mate group 16 of the periodic table and also including ternary rial may incorporate ions from group 12 (IIB) of the periodic and quaternary materials. Suitable nanoparticle semi table, such as ions selected from the group consisting of zinc, conductor materials include but are not restricted to cadmium and mercury. The non-III-V semiconductor mate rial may incorporate ions from group 14 (IVB). Such as lead Al2S3, Al-Sea. Al-Tes, Ga2S3, Ga-Sea: In-Ss. In Sea. ortin ions. The non-III-V semiconductor material may incor GaTes. In-Tes. porate ions from group 16 (VIB) of the periodic table. For 0094 IV-VI material incorporating a first element from example, ions selected from the group consisting of Sulfur, group 14 of the periodic table and a second element from selenium and telerium. The non-III-V semiconductor mate group 16 of the periodic table and also including ternary rial may incorporate ions from group 14 of the periodic table, and quaternary materials and doped materials. Suitable by way of example, carbide ions. The non-III-V semiconduc nanoparticle semiconductor materials include but are tor material may incorporate ions selected from the group not restricted to PbS, PbSe, PbTe, SnS, SnSe, SnTe. consisting of ions from the transition metal group of the 0.095 Nanoparticle material incorporating a first ele periodic table or ions from the d-block of the periodic table. ment from any group in the transition metal of the peri The non-III-V semiconductor material may incorporate ions odic table, and a second element from any group of the from group 13 (IIIB), for example, ions selected from the d-block elements of the periodic table and also including group consisting of boron, aluminium, gallium and indium, or ternary and quaternary materials and doped materials. ions from group 15 (VB) of the periodic table, such as ions Suitable nanoparticle semiconductor materials include selected from the group consisting of phosphide, arsenide and but are not restricted to NiS, CrS, CuInS. nitride, subject to the proviso that the non-III-V does not 0096. In addition to the above materials, the buffer layer incorporate ions from both group 13 and group 15. may also comprise: 0087. A buffer layer comprising or consisting essentially 0097 III-V material incorporating a first element from of a third material may be grown on the outside of the core, group 13 of the periodic table and a second element from between the core and the shell, if, for example, the two mate group 15 of the periodic table and also including ternary rials (core and shell) are incompatible or not sufficiently and quaternary materials and doped materials. Suitable compatible to facilitate acceptable growth of the shell layer of nanoparticle semiconductor materials include but are the second material. The third material may be a semiconduc not restricted to BP, AlP, AlAs. AlSb; GaN, GaP. GaAs, tor material incorporating ions from at least one of groups 2 to GaSb. InN, InP, InAs, InSb, AlN, BN. 16 of the periodic table. The third material may incorporate 0.098 Nanoparticles according to various aspects of the any of the ions set out above in respect of the non-III-V present invention may incorporate one or more layers of a semiconductor ions and/or may also include ions from both metal oxide material selected from the following: group 13 and group 15 of the periodic table in any desirable 0099 +1 Oxidation State combination. 0100 Silver(I) oxide, AgO; 0088. The non-III-V semiconductor material and/or buffer 01.01 +2 Oxidation State layer of semiconductor material may comprise: 0102 Aluminium monoxide, AlO; Barium oxide, BaO: I0089 IIA-VIB (2-16) material incorporating a first ele Beryllium oxide, BeO: Cadmium oxide, CdC); Calcium ment from group 2 of the periodic table and a second oxide, CaO; Cobalt(II) oxide, CoO; Copper(II) oxide, CuO; element from group 16 of the periodic table and also Iron (II) oxide. FeC); Lead (II) oxide, PbO; Magnesium (II) including ternary and quaternary materials and doped oxide, MgO, Mercury (II) oxide, HgO; Nickel (II) oxide, materials. Suitable nanoparticle semiconductor materi NiO: Palladium (II) oxide, PdO; Silver (II) oxide. AgO; US 2010/0283005 A1 Nov. 11, 2010

Strontium oxide, SrO: Tin oxide, SnO: Titanium (II) oxide, one or more of nickel, palladium and platinum. If selected TiO; Vanadium (II) oxide, VO; Zinc oxide, ZnO. from group 11 of the periodic table, the metal may be one or (0103 +3 Oxidation State more of copper, silver and gold. If selected from group 10 of 0104 Aluminium oxide, Al-O; Antimony trioxide, the periodic table, the metal may be one or more of zinc, Sb2O, Arsenic trioxide, ASO, Bismuth trioxide, BiO, cadmium and mercury, with Zinc being preferred. Boron oxide, B.O.; Chromium (III) oxide, CrOs. Erbium 0119) The metal may be a lanthanide. (III) oxide, Er-O, Gadolinium (III) oxide, GdO; Gallium I0120 If selected from group 14 of the periodic table, the (III) oxide, Ga-O; Holmium(III) oxide. HoO; Indium (III) metal may be one or more of silicon, germanium, tin or lead. oxide. In O. Iron (III) oxide, FeO; Lanthanum (III) oxide, If selected from group 55 of the periodic table, the metal may LaO, Lutetium (III) oxide, LuC); Nickel (III) oxide, be one or more of arsenic, antimony or bismuth. NiO; Rhodium (III) oxide, RhC); Samarium (III) oxide, Sm-O. Scandium (III) oxide, ScC: Terbium (III) oxide, I0121. It will be appreciated that the fifth and sixth aspects TbO; Thallium (III) oxide, Tl2O: Thulium (III) oxide, of the present invention are suitable to produce nanoparticles Tm2O: Titanium (III) oxide, TiO, Tungsten (III) oxide, comprising a core and layer, wherein one of the core and layer WO; Vanadium (III) oxide, VO: Ytterbium (III) oxide, is a III-V semiconductor material and the other is a metal YbO, Yttrium (III) oxide, Y.O. oxide material in which the metal is taken from any appro 0105 +4 Oxidation State priate group of the periodic table. Thus, with regard to nano 0106 Cerium (IV) oxide, CeO; Chromium (IV) oxide, particles formed according to the second and fifth aspects of CrO; Germanium dioxide, GeO: Hafnium (IV) oxide, the present invention, the metal of the metal oxide may be HfO; Lead (IV) oxide, PbO; Manganese(IV) oxide, MnO: taken from any one of groups 1 to 12, 14 and 15, but further, Plutonium (IV) oxide, PuO; Ruthenium (IV) oxide, RuO: the metal may be selected from group 13 of the periodic table Silicon (IV) oxide, SiO2; Thorium dioxide, ThC; Tin diox and therefore may be selected from the group consisting of ide, SnO, Titanium dioxide, TiO, Tungsten (IV) oxide, boron, aluminium, gallium, indium and thallium. WO, Uranium dioxide, UO; Vanadium (IV) oxide, VO: I0122. In an embodiment of the first aspect of the invention, Zirconium dioxide, ZrO. the nanoparticle comprises a core of indium phosphide and a 01.07 +5 Oxidation State shell of Zinc oxide grown on the core. The nanoparticle may 0108 Antimony pentoxide, SbOs: Arsenic pentoxide, beformed by growing a core of indium phosphide on a II-VI As Os: Niobium Pentoxide, NbOs: Tantalum pentoxide, semiconductor cluster, such as Zinc sulfide, and then depos Ta2O5; Vanadium (V) oxide, VOs. iting a shell of Zinc oxide by thermal decomposition of a 0109 +6 Oxidation State zinc-containing carboxylic acid solution. 0110. Chromium trioxide, CrOs. Molybdenum (VI) I0123. In other aspects, the invention is directed to the oxide, MoC); Rhenium trioxide, ReO; Tellurium trioxide, preparation of nanoparticulate materials incorporating a Te0: Tungsten trioxide, WO, Uranium trioxide, UO. semiconductor material and metal oxide material, wherein 0111 +7 Oxidation State the metal is taken from one of group 3 to 10 of the periodic 0112 Manganese (VII) oxide, MnO,; Rhenium (VII) table, and includes compound semiconductor particles other oxide, ReO7. wise referred to as quantum dots or nanocrystals within the 0113 Mixed Oxides size range 2-100 nm. 0114 Indium tin oxide and indium zinc oxide 0.124. The semiconductor material may form the core 0115 Concerning the first aspect of the present invention, material of the nanoparticle. In some embodiments the same the metal oxide material(s) of the nanoparticle core and/or or a different semiconductor material may form one or more any number of shell layers may bean oxide of any metal taken shell layers around the nanoparticle core, Subject to the pro from groups 1 to 12, 14 or 15 of the periodic table. Viso that the nanoparticle material also incorporates a mate 0116. If selected from group 1 of the periodic table, the rial that is an oxide of a metal chosen from one of groups 3 to metal may be one or more of lithium, Sodium or potassium. If 10 of the periodic table. The semiconductor material in the selected from group 2 of the periodic table, the metal may be nanoparticle core and/or one or more shells provided on the one or more of beryllium, magnesium, calcium, strontium or core may comprise ions selected from at least one of groups 2 barium. If selected from group 3 of the periodic table, the to 16 of the periodic table. metal may be one or more of scandium or yttrium. If selected 0.125. The semiconductor material may incorporate ions from group 4 of the periodic table, the metal may be one or from group 2 (IIA) of the periodic table, which may one or more of titanium, Zirconium or hafnium. more of magnesium, calcium or strontium. The semiconduc 0117 If selected from group 5 of the periodic table, the tor material may incorporate ions from group 12 (IIB) of the metal may be one or more of vanadium, niobium ortantalum. periodic table, such as one or more of Zinc, cadmium or If selected from group 6 of the periodic table, the metal may mercury. The semiconductor material may incorporate ions be one or more of chromium, molybdenum or tungsten. If from group 13 (IIIB), for example, one or more of boron, selected from group 7 of the periodic table, the metal may be aluminium, gallium or indium. The semiconductor material one or more of manganese or rhenium. If selected from group may incorporate ions from group 14 (IV). Such as lead and/or 8 of the periodic table, the metal may be one or more of iron, tinions. By way of further example, the group 14 ions may be ruthenium and osmium. The group 8 metal is desirably iron. carbide ions. The iron oxide may have a formula selected from the group 0.126 The semiconductor material may incorporate ions consisting of Fe0. FeO and FeO and is most preferably from group 16 (VIB) of the periodic table, such as one or more Y-Fe-O. of sulfur, selenium or telurium. There may be incorporated in 0118. If selected from group 9 of the periodic table, the the semiconductor material ions from group 15 (VB) of the metal may be one or more of cobalt, rhodium and iridium. If periodic table. Such as one or more of phosphide, arsenide or selected from group 10 of the periodic table, the metal may be nitride. The semiconductor material may incorporate ions US 2010/0283005 A1 Nov. 11, 2010 from the transition metal group of the periodic table and/or but is not necessarily restricted to materials of this compat ions from the d-block of the periodic table. ibility. A buffer layer comprising a third material may be 0127. The nanoparticle core semiconductor material may grown on the outside of the core, between the core and the comprise: shell if, for example the two materials, core and shell, are I0128 IIA-VIB (2-16) material incorporating a first ele incompatible or not sufficiently compatible to facilitate ment from group 2 of the periodic table and a second acceptable growth of the second material on the core. The element from group 16 of the periodic table and also third material may be a semiconductor material incorporating including ternary and quaternary materials and doped ions from at least one of groups 2 to 16 of the periodic table. materials. Suitable nanoparticle semiconductor materi I0137 The nanoparticle shell or buffer layer semiconduc als include but are not restricted to MgS, MgSe, MgTe, tor material may comprise: CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe. I0138 IIA-VIB (2-16) material incorporating a first ele I0129. IIB-VIB (12-16) material incorporating a first ment from group 2 of the periodic table and a second element from group 12 of the periodic table and a second element from group 16 of the periodic table and also element from group 16 of the periodic table and also including ternary and quaternary materials and doped including ternary and quaternary materials and doped materials. Suitable nanoparticle semiconductor materi materials. Suitable nanoparticle semiconductor materi als include but are not restricted to MgS, MgSe, MgTe, als include but are not restricted to ZnS, ZnSe, ZnTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe. CdS, CdSe, CdTe. HgS, HgSe, HgTe. 0139 IIB-VIB (12-16) material incorporating of a first 0130 II-V material incorporating a first element from element from group 12 of the periodic table and a second group 12 of the periodic table and a second element from element from group 16 of the periodic table and also group 15 of the periodic table and also including ternary including ternary and quaternary materials and doped and quaternary materials and doped materials. Suitable materials. Suitable nanoparticle semiconductor materi nanoparticle semiconductor materials include but are als include but are not restricted to ZnS, ZnSe, ZnTe, not restricted to Zn-P, ZnAs2. Cd-P, Cd. As Cd N, CdS, CdSe, CdTe. HgS, HgSe. HgTe. Zn-N. 0140 II-V material incorporating a first element from 0131 III-V material incorporating a first element from group 12 of the periodic table and a second element from group 13 of the periodic table and a second element from group 15 of the periodic table and also including ternary group 15 of the periodic table and also including ternary and quaternary materials and doped materials. Suitable and quaternary materials and doped materials. Suitable nanoparticle semiconductor materials include but are nanoparticle semiconductor materials include but are not restricted to Zn-P, ZnAs, CdP, Cd. As Cd N, not restricted to BP. AlP. AlAs. AlSb: GaN, GaP, GaAs, Zn-N. GaSb. InN, InP, InAs, InSb, AlN, BN. 0141 III-V material incorporating a first element from (0132 III-IV material incorporating a first element from group 13 of the periodic table and a second element from group 13 of the periodic table and a second element from group 15 of the periodic table and also including ternary group 14 of the periodic table and also including ternary and quaternary materials and doped materials. Suitable and quaternary materials and doped materials. Suitable nanoparticle semiconductor materials include but are nanoparticle semiconductor materials include but are not restricted to BP. AlP, AlAs. AlSb; GaN, GaP. GaAs, not restricted to BC, Al C. GaC. GaSb: InN, InP, InAs, InSb, MN, BN. 0.133 III-VI material incorporating a first element from 0142 III-IV material incorporating a first element from group 13 of the periodic table and a second element from group 13 of the periodic table and a second element from group 16 of the periodic table and also including ternary group 14 of the periodic table and also including ternary and quaternary materials. Suitable nanoparticle semi and quaternary materials and doped materials. Suitable conductor materials include but are not restricted to nanoparticle semiconductor materials include but are Al2S3, Al2Ses. Al-Tes. Ga2S3, Ga-Sea.GeTe; In-Ss. not restricted to B.C. AlC. GaC. In-Sea, Ga-Tes. In-Tes. InTe. I0143 III-VI material incorporating a first element from 10134) IV-VI material incorporating a first element from group 13 of the periodic table and a second element from group 14 of the periodic table and a second element from group 16 of the periodic table and also including ternary group 16 of the periodic table, and also including ternary and quaternary materials. Suitable nanoparticle semi and quaternary materials and doped materials. Suitable conductor materials include but are not restricted to nanoparticle semiconductor materials include but are Al2Ss. Al2Ses. Al-Tes. Ga2S3, Ga-Sea: In-Ss, In-Sea. not restricted to PbS, PbSe, PbTe, SnS, SnSe, SnTe. GaTes, InTes. I0135 Nanoparticle semiconductor material incorporat 0144) IV-VI material incorporating a first element from ing a first element from any group in the transition metal group 14 of the periodic table and a second element from of the periodic table, and a second element from any group 16 of the periodic table and also including ternary group of the d-block elements of the periodic table and and quaternary materials and doped materials. Suitable also including ternary and quaternary materials and nanoparticle semiconductor materials include but are doped materials. Suitable nanoparticle semiconductor not restricted to PbS, PbSe PbTe, SnS, SnSe, SnTe. materials include but are not restricted to NiS, CrS, (0145 Nanoparticle material incorporating a first ele CuInS. ment from any group in the transition metal of the peri 0136. The material used on any shell or subsequent num odic table, and a second element from any group of the bers of shells in most cases will be of a similar lattice type d-block elements of the periodic table and also including material to the immediate inner layer upon which the next ternary and quaternary materials and doped materials. layer is being grown, i.e., have close lattice match to the Suitable nanoparticle semiconductor materials include immediate inner material so that it may be epitaxially grown, but are not restricted to NiS, CrS, CuInS. US 2010/0283005 A1 Nov. 11, 2010

0146 The metal oxide material(s) in the nanoparticle core Stoichiometric amounts of components E and L), a source and/or any number of shell layers may be an oxide of any (i.e., precursor) for element M is added to the reaction and metal taken from groups 3 to 10 of the periodic table. may be any M-containing species having the ability to pro 0147 The metal may be selected from any one of groups 5 vide the growing particles with a source of M ions. The to 10 of the periodic table. More preferably the metal is precursor may comprise, but is not restricted to, an organo selected from any one of groups 6 to 9 of the periodic table, metallic compound, an inorganic salt, a coordination com and still more preferably the metal is selected from any one of pound or the element. groups 7 to 9 of the periodic table. It is particularly preferred (O157 With respect to element M, examples for II-VI, III that the metal is selected from group 8 of the periodic table. V, III-VI and IV-V semiconductor materials include but are The group 8 metal may be selected from the group consisting not restricted to: of iron, ruthenium and osmium, and is most preferably iron. 0158 Organometallic compounds such as but not The iron oxide may have a formula selected from the group restricted to a MR where M=Mg R-alky or aryl group consisting of Fe0, Fe2O and FeO, and is most preferably (MgTBu); MR where M-Zn, Cd, Te: R-alky or aryl maghemite or Y-Fe2O. group (MeZn, EtZn MeCd, EtCd); MR Where 0148. The metal oxide may include but is not restricted to M-Ga, In, Al, B: R-alky or aryl group AlR. GaR. oxides of the following transition metals: Scandium (Sc), InR (R=Me, Et, Pr). Yttrium (Y), Titanium (Ti), Zirconium (Zr), Hafnium (Hf), 0159 Coordination compounds such as a carbonate but Vanadium (V), Niobium (Nb), Tantalum (Ta), Chromium not restricted to a MCO M=Ca, Sr., Ba, magnesium (Cr), Molybdenum (Mo), Tungsten (W), Manganese (Mn), carbonate hydroxide (MgCO). Mg(OH); M(CO) Rhenium (Re), Iron (Fe), Ruthenium (Ru), Osmium (Os), M=Zn, Cd: MCO, M=Pb: acetate: M(CHCO) Cobalt (Co), Rhodium (Rh), Iridium (Ir), Nickel (Ni), Palla M=Mg, Ca, Sr. Ba; Zn, Cd, Hg: M(CHC), M=B, Al, dium (Pd), and Platinum (Pt). Ga, In: a 3-diketonate or derivative thereof, such as 0149. In preferred embodiments of the first and third acetylacetonate (2.4-pentanedionate) aspects of the present invention, the nanoparticle comprises a CHCOOCH=C(O-)CHI, MMg, Ca, Sr., Ba, Zn, core of indium phosphide and a shell of iron oxide, preferably Cd. Hg. CHCOOCH=C(O-)CHI, M=B, Al. Ga, Y-Fe-O, grown on the core. The nanoparticle is preferably In. Oxalate SrCO, CaCO BaCO, SnCO. formed by growing a core of indium phosphide on a II-VI 0.160 Inorganic salts such as but not restricted to an semiconductor cluster, such as Zinc sulfide, and then depos oxide (e.g., SrO, ZnO, CdO. In O, Ga.O., SnO, PbO) iting a shell of iron oxide derived from iron cupferron, pref or a nitrate (e.g., Mg(NO), Ca(NO), Sr(NO), erably Fe(cup). Ba(NO), Cd(NO), Zn(NO), Hg(NO), Al(NO), 0150 Nanoparticles within the first and third aspects of In(NO), Ga(NO), Sn(NO), Pb(NO)) the present invention and formed using the methods described 0.161 Elemental sources such as but not restricted to herein include not only binary-phase materials incorporating Mg, Ca, Sr., Ba, Zn, Cd, Hg, B, Al. Ga, In, Sn, Pb. two types of ions, but also ternary- and quaternary-phase (0162 E Ion Source nanoparticles incorporating, respectively, three or four types 0163 For a compound semiconductor nanoparticle mate of ions. It will be appreciated that ternary phase nanoparticles rial having the formula (ME),L, (where M-first element, have three component materials and quaternary phase nano E-Second element, Lligand (e.g., coordinating organic particles have four component materials. layer/capping agent), and n and m represent the appropriate 0151. Doped nanoparticles are nanoparticles of the above Stoichiometric amounts of components E and L), a source type which further incorporate a dopant comprising one or (i.e., precursor) for element E is added to the reaction and may more main group or rare earth elements, most often a transi be any E-containing species that has the ability to provide the tion metal or rare earth element, such as, but not limited to, growing particles with a source of E ions. The precursor may Mnt or Cut. comprise, but is not restricted to, an organometallic com 0152 Nanoparticle Shape pound, an inorganic salt, a coordination compound or the 0153. The shape of the nanoparticle is not restricted to a element. sphere and may take any desirable shape, for example, a rod, 0164. With respect to element E, examples for an II-VI, sphere, disk, tetrapod or star. The control of the shape of the III-V, III-VI or IV-V semiconductor materials include but are nanoparticle may be achieved in the reaction particle-growth not restricted to: process by the addition of a compound that will preferentially 0.165. Organometallic compounds such as but not bind to a specific lattice plane of the growing particle and restricted to a NR, PR, AsR, SbR (R-Me, Et, Bu, Subsequently inhibit or slow particle growth in a specific Bu, Pr, Phetc.); NHR, PHR, AsHR, SbHR (R=Me, direction. Without restriction, examples of compounds that Et, Bu, Bu, Pr, Phetc.); NHR, PHR, Ash R, SbH.R. may be added include: phosphonic acids (n-tetradecylphos (R=Me, Et, Bu, Bu, Pr, Phetc.); PH, Ash: M(NMe), phonic acid, hexylphoshonic acid, 1-decanesulfonic acid, M=P, Sb, As; dimethyldrazine (MeNNH); ethylazide 12-hydroxydodecanoic acid, n-octadecylphosphonic acid). (Et-NNN): hydrazine (HNNH); MeSiN. 0154 The precursors used for the semiconductor material (0166 MR (M=S, Se Te: R=Me, Et, Bu, Bu, and the (s) that may form the nanoparticle core and/or any outer shell like.); HMR (M=S, Se Te: R=Me, Et, Bu, Bu, Pr, Ph. layers or Subsequent shell layers may be provided from sepa and the like); thiourea S—C(NH); Se—C(NH2). rate sources or from a single source. 0.167 Sn(CH), Sn(CH), Sn(CH)(OOCH). O155 MIon Source 0168 Coordination compounds such as but not 0156 For a compound semiconductor nanoparticle mate restricted to a carbonate, MCO M=P. bismuth subcar rial having the formula (ME),L, (where M=first element, bonate (BiO)CO; M(CO); acetate M(CHCO) E-Second element, Lligand (e.g., coordinating organic M=S, Se, Te: M(CHC), M=Sn, Pb: a B-diketonate or layer/capping agent), and n and m represent the appropriate derivative thereof. Such as acetylacetonate (2.4-pen US 2010/0283005 A1 Nov. 11, 2010 12

tanedionate) (CHCOOCH=C(O-)CHM M=Bi; 0190. The metal oxide precursor may be but is not CHCOOCH=C(O )CHM M=S, Se, Te: restricted to the following: CHCOOCH=C(O-)CHM M=Sn, Pb: thiourea, (0191). Oxides of Group 1 (IA) selenourea (HNC(=Se)NH, 0.192 Lithium (Li), Sodium (Na). Potassium (K) 0169. Inorganic salts such as but not restricted to the (0193 Oxides of Group 2 (IIA) oxides P.O.s, ASO, Sb2O, Sb2O, Sb2O.s, BiO, SO, 0194 Beryllium (Be), Magnesium (Mg), Calcium (Ca), SeO, Te0, SnO, PbO, PbO; Nitrates Bi(NO), Strontium (Sr) Barium (Ba) Sn(NO), Pb(NO), (0195 Oxides of the Transition Elements, Groups 3-12 (0170 Elemental sources such as but not restricted to Sn, (IIIB, IVB, VB, VIB, VIIB, VIIIB, IB, IIB) Ge, N, PAs, Sb, Bi, S, Se, Te, Sn, Pb. 0196. Scandium (Sc), Yttrium (Y), Titanium (Ti), Zirco nium (Zr), Hafnium (Hf), Vanadium (V), Niobium (Nb), Tan (0171 Combined ME Ion Sources ME Single Source talum (Ta), Chromium (Cr), Molybdenum (Mo), Tungsten Precursors (W), Manganese (Mn), Rhenium (Re), Iron (Fe), Ruthenium 0172 For a compound semiconductor nanoparticle com (Ru), Osmium (Os), Cobalt (Co), Rhodium (Rh), Iridium (Ir). prising elements Mand E, a source for elements Mand E may Nickel (Ni), Palladium (Pd), Platinum (Pt), Copper (Cu), be in the from of a single-source precursor, whereby the Silver (Ag), Gold (Au), Zinc (Zn), Cadmium (Cd) and Mer precursor to be used contains both M and E within a single cury (Hg). For example, the metal oxide precursor may be but molecule. is not restricted to oxides of the following transition metals: 0173 This precursor may be an organometallic com Scandium (Sc), Yttrium (Y), Titanium (Ti), Zirconium (Zr), pound, an inorganic salt or a coordination compound, (M.E.) Hafnium (Hf), Vanadium (V), Niobium (Nb), Tantalum (Ta), L where M and E are the elements required within the nano Chromium (Cr), Molybdenum (Mo), Tungsten (W), Manga particles, L is the capping ligand, and a, b and c are numbers nese (Mn), Rhenium (Re), Iron (Fe), Ruthenium (Ru), representing the appropriate stroichiometry of M, E and L. Osmium (Os), Cobalt (Co), Rhodium (Rh), Iridium (Ir). Nickel (Ni), Palladium (Pd), and Platinum (Pt). 0.174 Examples for a II-VI semiconductor where M=II 0.197 Oxides of the Lanthanides and E=VI element may be but are not restricted to bis(dialky 0198 Lanthanum (La), Cerium (Ce), Praseodymium (Pr), ldithio-carbamato)M.(II) complexes or related Se and Te Neodymium (Nd), Samarium (Sm), Europium (Eu), Gado compounds of the formula M(SCNR) M=Zn, Cd, Hg: linium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium S—S, Se, O, Te and R-alkyl orary groups; CdS CdSSiMe. (Ho), Erbium (Er), ThuliumTM, Ytterbium (Yb), Lutetium Cd(SCNHNH2)C1, Cd(SOCR), py; CdSe (Cd(SePh). (Lu). (0175 For III-V semiconductors the precursors may be but (0199 Oxides of Group 13(IIIA) For Use in the Fifth and are not restricted to: Sixth Aspects of the Present Invention. (0176 for GaN: (Me)GaN(H)"Bull, H.GaNH): 0200 Boron (B), Aluminium (Al), Gallium (Ga), Indium (0177 for GaP: PhGaP(SiMe)Ga(Ph)C1EtGaP (In), Thallium (Tl) (SiMe), EtGaPEt), TBuGalPH Me,GaP(Pr) 0201 Oxides of Group 14 (IVA) TBuGaPAir, TBuGalP(H)CHo); 0202 Silicon (Si), Germanium (Ge), Tin (Sn), Lead (Pb) (0178 for GaAs: Ga(As Bu) (EtGaAs(SiMe), (0203 Oxides of Group 15 (VA) TBuGaAS(SiMe)); 0204 Arsenic (As), Antimony (Sb), Bismuth (Bi) (0179 for GaSb: EtGaSb(SiMe): 0205. In a preferred method for providing a shell layer of metal oxide, a molecular complex containing both the metal 0180 for InP: (MeSiCH), InP(SiMe), RInP ions and oxide ions to be incorporated into the metal oxide (SiMe), MeInPBul; layer may be used. The complex may be added to the nano 0181 for InSb: Me, InSb'Bus Et InSb(SiMe), particle cores (e.g., InP or CdSe) in a single portion or a MeInNEt), Eta AlAs Bul; plurality (e.g., 2, 3, 4 or 5) of portions sufficient to provide the 0182 for AISb: TBuAISb(SiMe)); required amount of metal ions and oxide ions. 0183 for GaAs: "BuGaAs Bu Me,GaAs Bu 0206. A preferred oxide ion containing anionic complex EtGaAs Bull. that may be used in combination with a suitable metal cation 0184 For II-V semiconductors the precursors may be but is N-nitrosophenylhydroxylamine (cupferron). This anionic are not restricted to, for CdP, MeCdP'Bus CdIP(SiPh.) complex is particularly suitable for use with ferric ions. I, Zn-P ZnP(SiPh). Accordingly, a particularly preferred complex used to pro vide an iron oxide shell on a semiconductor core nanoparticle 0185. For IV-VI semiconductors the precursors may be is ferric cupferron. but are not restricted to: 0207. It may be advantageous to heat a solution containing 0186 for PbS: lead (II) dithiocarbamates: the nanoparticle cores prior to addition of the molecular com 0187 for PbSe: lead (II)selenocarbamates. plex. Suitable temperatures may be in the range around 150° 0188 Metal-Oxide Outer Layer C. to around 300° C., more preferably around 180° C. to 0189 For the growth of the metal oxide core and/or shell around 270° C., still more preferably around 200° C. to layer(s), a Source for the metal element is added to the reac around 250° C. and most preferably around 220° C. to around tion and may comprise any metal-containing species that has 2300 C. the ability to provide the growing particles with a source of 0208 Following addition of the molecular complex (when the appropriate metal ions. The precursor may also be the a single portion is used) or addition of the final portion of the Source of the oxygen atoms if they are present within the molecular complex (when two or more portions are used) it precursor or the oxygen source may be from a separate oxy may be desirable to cool the nanoparticle solution to a lower gen-containing precursor including oxygen. The precursor temperature, for example, around 160° C. to around 200°C., may comprise but is not restricted to an organometallic com more preferably around 180° C., depending in part upon the pound, an inorganic salt, a coordination compound or the temperature of the nanoparticle solution prior to and during element itself. addition of the molecular complex. US 2010/0283005 A1 Nov. 11, 2010

0209 Following cooling, the nanoparticle solution may diffraction (PXRD) measurements were preformed on a then be maintained at the cooler temperature over a period of Bruker AXS D8 diffractometer using monochromated Cu time to allow the nanoparticles to anneal. Preferred annealing Koo radiation. periods are in the range around 1 hour to around 72 hours, more preferably around 12 hours to around 48 hours, and Example 1 most preferably around 20 to 30 hours. Preparation of InP/ZnO Core/Shell Nanoparticles 0210. Following annealing, it may be appropriate to fur (Red) ther cool the nanoparticle solution to a lower temperature 0218 InP core particles were made as follows: 200 ml (e.g., around 30° C. to around 100° C., more preferably di-n-butylsebacate ester and 10 g myristic acid at 60°C. were around 50° C. to around 80° C., more preferably around 70° placed in a round-bottomed three neck flask and purged with C.) to restrict further nanoparticle growth and facilitate iso N this was followed by the addition of 0.94 g of the ZnS lation of the final metal oxide coated nanoparticles. cluster HNEtaZnS,(SPh). The reaction was then 0211 A further preferred method for providing a shell heated to 100° C. for 30 mins followed by the addition of 12 layer of metal oxide involves decomposition of a metal car ml of 0.25M In(Ac)(MA), dissolved in di-n-butylseba boxylate in the presence of a long chain (e.g., C-C) alco cate ester, overa period of 15 mins using an electronic syringe hol to yield the metal oxide, which may be deposited on the pump at a rate of 48 ml/hr, this was followed by the addition nanoparticle core, and an ester as the bi-product. In this of 12 ml 0.25M (TMS)P at the same addition rate. method, the metal carboxylate is preferably added to a solu 0219. Once additions were complete the temperature of tion containing the nanoparticle cores, which then heated to a the reaction was increased to 180°C. To grow the particles up first elevated temperature before addition of a solution con to the required size and thus the required emission in the red, taining a predetermined amount of the long chain alcohol. further addition of solutions of In(Ac),(MA), and (TMS) The mixture is then preferably maintained at the first tem P were made as followed:—16 ml In(Ac)(MA) fol perature for a predetermined period of time. The temperature lowed by 16 ml (TMS)P were added followed by a tempera ture increase to 200° C. then further additions of 10 ml of of the mixture may then be further increased to a second In(Ac)(MA), the temperature was then left at 200° C. for temperature and maintained at that increased temperature for 1 hr and then lowered to 160° C. and the reaction allowed to a further period of time before cooling to around room tem anneal for 3 days. Then the particles were isolated using perature at which point the metal oxide coated nanoparticles acetonitrile, centrifuged and collected. The InP quantum dots may be isolated. had an emission peak at 550 nm. 0212. The first elevated temperature is preferably in the 0220. The formation of a ZnO shell is based on the decom range around 150° C. to around 250° C., more preferably position product of a suitable metal carboxylic acid with a around 160°C. to around 220°C., and most preferably around long chain alcohol yielding an ester as the bi-product. InP 180° C. Subject to the proviso that the second temperature is core dots 165.8 mg prepared as described above were dis higher than the first temperature, the second temperature is solved in 10 ml of di-n-butylsebacate ester. This was then preferably in the range around 180° C. to around 300° C. added to a 3 neck round-bottom flask containing Zinc acetate more preferably around 200°C. to around 250° C., and most and myristic acid and the flask was then degassed and purged preferably around 230° C. with N several times. In a separate flaska solution of 1-oc tadecanol (2.575 g, 9.522 mmol) and ester 5 ml of di-n- 0213. The alcoholic solution is preferably added slowly to butylsebacate ester was made up at 80° C. the carboxylate solution, for example, the alcoholic Solution 0221) The reaction solution containing the dots was then may be added over a period of at least 2 to 3 minutes, if not heated to 180° C. at which temperature the alcohol solution longer, Such as 5 to 10 minutes or even longer. was slowly added over a period of 5-10 minutes. The tem 0214. The temperature of the reaction mixture may be perature of the reaction was then maintained for 30 minutes maintained at the first temperature for at least around 5 to 10 followed increasing the temperature to 230° C. and main minutes and more preferably longer, such as at least around tained at this temperature for 5 minutes before cooling to 20 to 30 minutes or even longer. After raising the temperature room temperature. of the reaction mixture to the second temperature it is pre 0222. The sample was isolated by the addition of excess ferred that the mixture is maintained at this increased tem acetonitrile, centrifuging the resulting wet solid pellet was perature for at least around 1 to 2 minutes and more preferably further washed with acetonitrile and centrifuging for a second longer, for example at least around 4 to 5 minutes or still time. The resulting pellet was dissolved with chloroform and longer. filtered to remove any remaining insoluble material. 0215 Embodiments of the present invention are illus trated with reference to the following non-limiting examples. Example 2 Preparation of InP/ZnS/ZnO Core/Shell/Shell Nano Examples particles 0216 All syntheses and manipulations were carried out 0223) InP core particles were made as follows: 200 ml under a dry oxygen-free argon or nitrogen atmosphere using di-n-butylsebacate ester and 10 g myristic acid at 60°C. were standard Schlenk or glove box techniques unless other wise placed in a round-bottomed three neck flask and purged with stated. All solvents were distilled from appropriate drying N this was followed by the addition of 0.94 g of the ZnS agents prior to use (Na?k-benzophenone for THF, EtO, tolu cluster HNEtaZnS,(SPh). The reaction mixture was ene, hexanes and pentane). then heated to 100° C. for 30 mins followed by the addition of 0217. UV-vis absorption spectra were measured on a 12 ml of 0.25M In(Ac),(MA), dissolved in di-n-butylse Hewios? Thermospectronic. Photoluminescence (PL) spectra bacate ester, over a period of 15 mins using an electronic were measured with a Fluorolog-3 (FL3-22) photospectrom syringe pump at a rate of 48 ml/hr, this was followed by the eter and using Ocean Optics instruments. Powder X-Ray addition of 12 ml 0.25M (TMS)P at the same addition rate. US 2010/0283005 A1 Nov. 11, 2010

0224. Once additions were complete the temperature of electronic syringe pump at a rate of 48 ml/hr, this was fol the reaction was increased to 180°C. To grow the particles up lowed by the addition of 12 ml of a 0.25M solution of (TMS) to the required size and thus the required emission in the red, P dissolved in di-n-butylsebacate ester at the same addition further addition of solutions of In(Ac)(MA) and (TMS) rate. P were made as followed:—16 ml In(Ac)(MA) fol lowed by 16 ml (TMS)P were added followed by a tempera 0234. Once additions were complete the temperature of ture increase to 200° C. then further additions of 10 ml of the reaction was increased to 180°C. To grow the particles up In(Ac)(MA), the temperature was then left at 200°C. for to the required size and thus the required emission in the red, 1 hr and then lowered to 160° C. and the reaction allowed to further addition of In(Ac)(MA) and (TMS)P were made anneal for 3 days. Then the particles were isolated using as follows: 16 ml In(Ac)(MA) followed by 16 ml (TMS) acetonitrile, centrifuged and collected. The InP quantum dots P were added followed by a temperature increase to 200° C. had an emission peak at 550 nm. then further additions of 10 ml of In(Ac)(MA), the tem 0225. Two methods using different S sources (Method 1. perature was then left at 200° C. for 1 hr and then lowered to (TMS)S; Method 2, octanethiol) were employed to form a 160° C. and the reaction allowed to anneal for 3 days. The buffer layer of ZnS on the InP core nanoparticles prior to particles were isolated using acetonitrile, centrifuged and addition of the ZnO outer shell. These are described in turn. collected. The InP quantum dots had an emission at 550 nm. 0226 Method 1 0235. The InP nanoparticles were precipitated with 0227 3.13 g (13.7 mmol) of myristic acid and 6.75 ml of methanol and isolated as a pellet by centrifugation. The Super di-n-butyl sebacate ester were degassed. 300 mg of the HF nate was discarded and 1.0 g of the InP pellet were placed in etched InP dots and 1.68 g (9.15 mmol) of anhydrous zinc a 125 mL round-bottom flask containing 50 g hexadecy acetate was added at room temperature. The solution was lamine that had previously been dried and degassed under slowly heated to 180° C.9.2 ml (2.3 mmol) of 0.25M (TMS) S was added dropwise and after completion the mixture was Vacuum at 120° C. stirred for 30 minutes. 0236. The solution temperature was raised to 23.0°C. and 0228. Method 2 3.30 mL of a 0.0286 M ferric cupferron solution in octy 0229. 3.13 g of myristic acid and 6.75 ml of di-n-butyl lamine was added dropwise over a 10-minute period. The sebacate ester were degassed. 300 mg of the HF etched InP solution was left stirring for an additional 20 minutes before dots and 1.68 g anhydrous Zinc acetate was added at room an aliquot was taken and a second 3.30 mL portion of ferric temperature. The solution was slowly heated to 120°C. 0.4 ml cupferron solution was added dropwise over a 10 minute (2.3 mmol) octanethiol was added in one portion and the period. The solution was stirred for 20 minutes and analiquot temperature increased to 180° C. where it was kept for 30 was taken. A third and final 3.30 mL portion of ferric cupfer minutes. ron solution was added dropwise over a 10 minute period. 0230. The formation of a ZnO shell is based on the decom 0237 After the final addition, the reaction was stirred for position product of a suitable metal carboxylic acid with a an additional 20 minutes, cooled to 180°C. and left stirring at long-chain alcohol yielding an ester as the bi-product. InP 180° C. for 24 hr before cooling to 70° C. Methanol was core dots (165.8 mg) prepared as described above were dis added to precipitate the particles. The precipitate was isolated solved in 10 ml of di-n-butylsebacate ester. This was then as a pellet by centrifugation and the Supernate was discarded. added to a 3-neck round-bottom flask containing Zinc acetate and myristic acid, and the flask was degassed and purged with 0238. The PL emission intensity for that of the core/shell N. several times. In a separate flaska solution of 1-octade particles was about 200 times more intense than that of the canol (2.575 g, 9.522 mmol) and ester 5 ml of di-n-butylse core particles prior to the addition of the Fe-O layer. A bacate ester was made up at 80°C. schematic representation of InP/FeO core/shell nanopar 0231. The reaction solution containing the dots were then ticles is shown in FIG. 3. heated to 180° C. at which temperature the alcohol solution was slowly added over a period of 5-10 minutes. The tem Example 4 perature of the reaction was then maintained for 30 minutes followed increasing the temperature to 230° C. and main 0239 Red-emitting InP nanoparticle cores were produced tained at this temperature for 5 minutes before cooling to as described in Example 1. room temperature. 0240. A method similar to that described in Example 1 was 0232. The sample was isolated by the addition of excess then used to deposit a layer of InO on the InP cores: 30 ml acetonitrile, centrifuging the resulting wet solid pellet was of the InP reaction solution was removed and then heated further washed with acetonitrile and centrifuging for a second under Ar to 180° C. Slowly 3 ml of octanol was added and time. The resulting pellet was dissolved with chloroform and then left for 30 minutes before cooling to room temperature. filtered to remove any remaining insoluble material. While the applicants do not wish to be bound by any particu lar theory, it is believed that excess InCMA) in the InP core Example 3 reaction Solution reacted with the octanol to depositan InO. shell on the InP cores. Preparation and Properties of InP/FeO Core/Shell 0241. It was observed that the quantum yield of the In-O Nanoparticles core/shell nanoparticles was 6 times greater than the quantum 0233. InP core particles were made as follows: 200 ml yield of the unshelled InP cores (see FIG. 5). di-n-butylsebacate ester and 10 g myristic acid at 60°C. were 0242. It is postulated that a shell of InO may act as a placed in a round-bottomed three-neck flaskand purged with buffer layer between InP cores and outer layers of ZnS and N this was followed by the addition of 0.94 g of the ZnS ZnO in nanoparticles produced according to Example 2 cluster HNEtaZnS,(SPh). The reaction was then above. On the basis of the improvement in quantum yield heated to 100° C. for 30 minutes followed by the addition of observed when InP cores were coated with InO, the addi 12 ml of 0.25M solution of In(Ac)(MA), dissolved in tion of a further buffer layer of InO (in addition to a buffer di-n-butylsebacate ester over a period of 15 minutes using an layer of ZnS) may improve both the final quantum yield US 2010/0283005 A1 Nov. 11, 2010

and/or stability of the InP/InO/ZnS/ZnO nanoparticle wise over a 10 minute period. The solution was stirred for 20 material as compared to the InP/ZnS/ZnO produced in min. A third and final 2.5 mL portion of ferric cupferron Example 2. solution was added dropwise over a 10 minute period. (0250. After the final addition, the reaction was stirred for Example 5 an additional 20 minutes, and the reaction was cooled to 180° C. The solution was left stirring at 180° C. for 4 hr before Synthesis of CdSe/FeO (with Green Emission) cooling to 70° C. and 15 mL of the reaction mixture was 0243 In a typical synthesis 100 g HDA (hexadecylamine) removed and placed in a centrifuge tube. A 45 mL portion of was degassed at 120° C. for an hour. The flask was then methanol was added to precipitate the particles. The precipi purged with nitrogen and 1.25 g of EtNHCdSe (SPh) tate was isolated as a pellet by centrifugation and the Super was added in one portion as a solid at 100°C. The solution nate was discarded. Portions of the pellet were redispersed in was slowly heated to 260° C. and kept at this temperature for toluene. about 1 hour. The solution was cooled to 150° C. and a further 0251. The formation of the FeCup layer produces a slight 0.25 g Et NHCdSe (SPh) was added. The solution red shift both in PL maximum and first absorption peak (see was reheated to 260° C. for a further hour or until the maxi FIG. 7) of -3.5 nm, which is considerably less than the shift mum emission peak reached 550 nm. The CdSe nanoparticles when either CdS or ZnS is grown epitaxially onto the particle. were collected by cooling the reaction solution, precipitating 0252 FIG. 7 shows that the XRD pattern of CdSe/y-Fe-O, with excess methanol centrifuging and drying with a nitrogen nanocrystals had a very similar shape to that of pure CdSe flow. cores, however a sharpening of the three major peaks for the 0244. A dilute solution of FeCup in octylamine was CdSe/Y-Fe2O may be seen. No noticeable peaks attributable made, 30 ml octylamine, 0.248 g FeCup was dissolved to to bulky-Fe-O, are evident in the diffraction pattern. give a 0.018M solution. In a separate flask, 75 g HDA was 0253 TEM images of CdSe nanoparticles revealed aver degassed at 120° C., then cooled to 100° C. and 0.3 g of the age diameters of 3.7 mm. The particle size increased to 4.2 mm 550 nm CdSe particles added. The temperature of the reaction when shelled with FeO. There appeared to be a slight aggre was raised to 230° C. and the Fe(Cup/octylamine solution gation of the nanoparticles after shelling with FeO, however was added dropwise in 5 Separate portions of 1 ml, 1 ml, 1 ml, the particles still easily dissolve in organic solvents. 2 ml and 5 ml making in total 10 ml of added solution. The reaction was left to stirfor 5 minutes in-between each portion. 0245. After the complete addition of FeCup reaction was Example 7 cooled to 180° C. and left to anneal for up to 3 hours, then cooled to room temperature and isolated by precipitating with Preparation of ZnSe/FeO Core/Shell Nanoparticles methanol, then centrifuging and dried with a nitrogen flow. 0246 Elemental analysis gave C=24.42. H=3.93, N=1.32, 0254. A 125 mL round-bottom flask was loaded with 25g Cd=42.46, Fe=2.61. octadecylamine and a spin-bar, the flask was attached to a schlenk line and evacuated. The solvent was dried and Example 6 degassed under vacuum for 1 hr at 120°C. The flask was filled with nitrogen and the temperature increased from 120° C. to Preparation of CdSe/FeO Core/Shell Nanoparticles 340°C. over a 2 hr period. At this point, 4 mL of a premixed (with Red Emission) precursor solution (0.25M diethyl Zinc and 0.25 M elemental 0247. A 25 g portion of hexadecylamine (HDA) was selenium dissolved in TOP) was injected into the flask. The placed in a three-neck round-bottomed flask and dried and reaction temperature plunged to 300° C. immediately follow degassed by heating to 120° C. under a dynamic vacuum for ing the precursor Solution injection and was maintained at >1 hour. The solution was cooled to 60°C., the reaction flask 300° C. was filled with nitrogen and the following reagents were 0255. An additional 16 mL portion of premixed precursor loaded into the flask using standard airless techniques: 0.10 g solution was added dropwise over a 4 hour period. The tem HNEtCdSe (SPh), 2 mL of a premixed precursor perature was lowered to 250° C. and the solution was left solution (a solution of 0.25M MeCd and 0.25 M elemental stirring overnight. The ZnSe nanoparticles were precipitated selenium dissolved in trioctylphosphine). The temperature with hot (70° C.) n-butanol and isolated as a pellet by cen was increased to 120° C. and allowed to stir for 2 hours. At trifugation. this point a programmed temperature ramp from 120° C. to 0256 The supernate was discarded and 125 mg of the 200° C. at a rate of ~0.2° C./min was initiated. Simulta ZnSe pellet was placed in a 125 mL round-bottom flask neously, an additional 4 mL of the premixed precursor Solu containing 25 g octadecylamine that had previously been tion was added dropwise at a rate of -0.05 mL/min. dried and degassed under vacuum at 120° C. The solution 0248 Particle growth was stopped when the PL emission temperature was raised to 220°C. and 2.5 mL of a 0.0286 M maximum had reached the required emission (W 585 nm) ferric cupferron Solution in octylamine was added dropwise by cooling to 60°C. followed by the addition of an excess of over a 10 minute period. The solution was left stirring for an dry methanol to precipitate the particles from solution. The additional 20 minutes before an aliquot was taken and a precipitate was isolated by centrifugation, the pellet was second 2.5 mL portion of ferric cupferron solution was added retained and the Supernate was discarded. dropwise over a 10 minute period. The solution was stirred for 0249. A 125 mg portion of the CdSe pellet was placed in a 20 minutes a third and final 2.5 mL portion offerric cupferron 125 mL round-bottom flask containing 25 g octadecylamine solution was added dropwise over a 10 minute period. that had previously been dried and degassed under vacuum at 0257. After the final addition, the reaction was stirred for 120° C. The solution temperature was raised to 220° C. and an additional 20 minutes and the reaction was allowed to cool 2.5 mL of a 0.0286 Mferric cupferron solution in octylamine to 180° C. The solution was left stirring at 180° C. for 4 hr was added dropwise over a 10 minute period. The solution before cooling to 70° C. A 15 mL portion of the reaction was left stirring for an additional 20 minutes before a second mixture was removed and placed in a centrifuge tube. A 45 2.5 mL portion of ferric cupferron solution was added drop mL portion of methanol was added to precipitate the particles. US 2010/0283005 A1 Nov. 11, 2010

The precipitate was isolated as a pellet by centrifugation and 0262 The ester was added to a 3-neck round bottomed the supernate was discarded. Portions of the pellet were redis flask equipped with condenser, thermometer and magnetic persed in toluene. stirrer bar then degassed under vacuum at 100° C. for two hours. Temperature decreased to 70° C. and put under nitro Example 8 gen atmosphere. Cluster was added in one portion and stirred Preparation and Properties of CdTe?FeO Core/ for 30 minutes. Temperature increased to 100°C. then 15 ml Shell Nanoparticles In(MA) was added dropwise. After complete addition the reaction was stirred for 5 minutes then was followed by the 0258. A 125 mL round-bottom flask was loaded with 25g dropwise addition of 15 ml (TMS)P. Temperature increased hexadecylamine and a spin-bar. The flask was attached to a to 160° C. then 20 ml Im(MA) was added dropwise. After schlenk line and evacuated. The solvent was dried and complete addition the reaction was stirred for 5 minutes then degassed under vacuum for 1 hr at 120°C. The flask was filled was followed by the dropwise addition of 8 ml (TMS)P. with nitrogen and the temperature increased from 120° C. to Temperature increased to 190° C. then 5 ml InCMA), was 260° C. over a 2 hr period. At this point, 4 mL of a premixed added dropwise. After complete addition the reaction was precursor solution (0.25 M dimethyl cadmium and 0.25 M stirred for 5 minutes then was followed by the dropwise elemental tellurium dissolved in TOP) was added. The reac addition of 3 ml (TMS)P. Temperature increased to 200° C. tion temperature plunged to 240° C. immediately following where it was left to stir for 1 hour. Temperature decreased to the precursor Solution injection and was maintained at 240° 160° C. and the quantum dots left to anneal for 3 days. C. for 5 minutes. The temperature was lowered to 50° C. by Temperature increased to 180°C. then the octanol was added removing the flask from the mantle and exposing it to a stream in one portion. The reaction was left to stirfor 30 minutes then of cool air. The CdTe nanoparticles were precipitated with cooled to room temperature. Anhydrous acetonitrile was methanol and isolated as a pellet by centrifugation. added until the particles flocculated then the precipitate was 0259. The supernate was discarded and 125 mg of the centrifuged. The wet powder was redissolved in minimum CdTe pellet were placed in a 125 mL round-bottom flask volume of chloroform and reprecipitated with methanol. The containing 25 g hexadecylamine that had previously been wet powder was redissolved again in the minimum Volume of dried and degassed under vacuum at 120° C. The solution chloroform then reprecipited with methanol. The dots were temperature was raised to 220°C. and 2.5 mL of a 0.0286 M dissolved in chloroform then etched using a dilute solution of ferric cupferron solution in octylamine was added dropwise HF in air over a period of 3 days until maximum luminescence over a 10 minute period. The solution was left stirring for an intensity was seen. additional 20 minutes a second 2.5 mL portion of ferric cup ferron solution was added dropwise over a 10 minute period. The solution was stirred for 20 minutes and then a third and final 2.5 mL portion of ferric cupferron solution was added dropwise over a 10 minute period. Shelling of InP, In O3 cores with ZnS/ZnO shell 0260. After the final addition, the reaction was stirred for Material Amount Moles MW Grade an additional 20 minutes, and the reaction was cooled to 180° InP, In2O3 cores 5.64 C. The solution was left stirring at 180° C. for 4 hr before in 50 ml ester cooling to 70° C. A 15 mL portion of the reaction mixture was Di-n-butyl- 70 ml O.O744 314.46 Tech removed and placed in a centrifuge tube. A 45 mL portion of sebacate ester methanol was added to precipitate the particles. The precipi Undecylenic acid 18 g O.O978 18428 98% Zinc acetate 15 g O.O818 183.46 99.99% tate was isolated as a pellet by centrifugation and the Super 1-Octanethiol 9 ml O.0519 146.29 98.5% nate was discarded. Portions of the pellet were redispersed in 1-Octanol 12.8 O.O813 130.23 99% toluene. Toluene 40 ml anhydrous Acetonitrile 180 ml anhydrous Example 9 Ethyl acetate 100 ml anhydrous Preparation and Properties of InP/InO/ZnS/ZnO Core/Shell Nanoparticles 0263. The ester, cores produced as described above and undecylenic acid were added together in a 3-neck round bot 0261 tomed flask equipped with condenser, thermometer and mag netic stirrer bar then degassed under vacuum for 2 hours at 100°C. The temperature was decreased to 70° C. then the zinc acetate was added in Small portions to one neck of the flask Synthesis of InP. In O3 cores under strong nitrogen flow. Temperature increased to 100° C. then the reaction was evacuated under reduced pressure for 20 Material Amount Moles MW Grade minutes then purged with nitrogen. Then evacuated/purged a Di-n-butyl-sebacate ester 250 ml (0.0744 314.46 tech further two times. Temperature increased to 120° C. then the EtNHZnoS (SPh) 9.4 g 0.0032 2937.67 Myristic acid 25 g 4,469x 228.37 99% octanethiol was added in one portion. Temperature increased 10 to 230° C. and held for 90 minutes. Temperature decreased to Indium myristate (1M solin in 40 ml (0.04 796.93 180° C. then the octanol was added in one portion and held at ester) 180° C. for 30 minutes. Solution was then cooled to room Tris(trimethylsilylphosphine) 26 ml (0.026 2SO.S4 temperature. Anhydrous acetonitrile was added until the par 1M solin in ester 1-Octanol 53.8 O3416 130.23 99% ticles flocculated then the precipitate was filtered through a Chloroform 50 ml anhydrous celite filled sinter funnel The precipitate was washed first with Methanol 100 mL. anhydrous hot acetonitrile (discarding the washings) then washed with Acetonitrile 250 mL. anhydrous hot ethylacetate (that dissolves the dots). The dots dissolved in the ethylacetate was then reprecipitated by adding aceto nitrile. Finally the precipitated dots was dissolved in mini US 2010/0283005 A1 Nov. 11, 2010

mum Volume of toluene and stored in an inert atmosphere. rial incorporating metal ions selected from any one of groups InP/InO/ZnS/ZnO core/shell nanoparticles were produced 1 to 12, 14 and 15 of the periodic table, the method compris emitting at 506 nm, with a full width at half maximum ing: (FWHM) of 55 nm and quantum yield (QY) of 50%. forming the core and forming thereover the layer compris 0264. The terms and expressions employed herein are ing the second material. used as terms and expressions of description and not of limi 26. The method of claim 25, wherein the core has a com tation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features position, formation of the core comprising (i) effecting con shown and described or portions thereof In addition, having version of a nanoparticle core precursor composition to the described certain embodiments of the invention, it will be composition of the nanoparticle core, and (ii) growing the apparent to those of ordinary skill in the art that other embodi COC. ments incorporating the concepts disclosed herein may be 27. The method of claim 26, wherein the nanoparticle core used without departing from the spirit and scope of the inven precursor composition comprises first and second core pre tion. Accordingly, the described embodiments are to be con cursor species containing ions to be incorporated into the sidered in all respects as only illustrative and not restrictive. growing nanoparticle core, the first and second core precursor What is claimed is: species being separate entities in the nanoparticle core pre 1. A nanoparticle comprising: cursor composition, the conversion being effected in the pres a core that itself comprises a first material; and ence of a molecular cluster compound under conditions per thereover, a layer that comprises a second material, mitting seeding and growth of the nanoparticle core. wherein one of the first and second materials is a semicon 28. (canceled) ductor material incorporating ions from group 13 and 29. The method of claim 26, wherein the nanoparticle core group 15 of the periodic table and the other of the first precursor composition comprises first and second core pre and second materials is a metal oxide material incorpo cursor species containing ions to be incorporated into the rating metalions selected from any one of groups 1 to 12, growing nanoparticle core, the first and second core precursor 14, and 15 of the periodic table. species being combined in a single entity contained in the 2-8. (canceled) core precursor composition. 9. The nanoparticle of claim 1, wherein the metal is 30. The method of claim 25, whereinformation of the layer selected from group 8 of the periodic table. comprising the second material comprises effecting conver 10. The nanoparticle of claim 9, wherein the group 8 metal sion of a second material precursor composition to the second is iron. material. 11. The nanoparticle of claim 10, wherein the iron oxide 31. The method of claim 30, wherein the second material has a formula selected from the group consisting of Fe0. precursor composition comprises third and fourth ions to be Fe2O, and FeO. incorporated into the layer comprising the second material, 12. The nanoparticle of claim 10, wherein the iron oxide is the third and fourth ions being separate entities contained in Y-Fe-O. the second material precursor composition. 13-14. (canceled) 32. (canceled) 15. The nanoparticle of claim 1, wherein the metal is 33. The method of claim 30, wherein the second material selected from group 11 of the periodic table. precursor composition comprises third and fourth ions to be 16. The nanoparticle of claim 1, wherein the metal is incorporated into the layer comprising the second material, selected from group 12 of the periodic table. the third and fourth ions being combined in a single entity 17. The nanoparticle of claim 1, wherein the metal is contained in the second material precursor composition. selected from group 13 of the periodic table. 34. The method of claim 25, wherein the first material is the 18-19. (canceled) semiconductor material incorporating ions from groups 13 20. The nanoparticle of claim 1, wherein the group 13 ions and 15 of the periodic table and the second material is the incorporated in the semiconductor material are selected from metal oxide. the group consisting of boron, aluminium, gallium, and 35. The method of claim 30, wherein the second material indium. precursor composition comprises the metalions and the oxide 21. The nanoparticle of claim 1, wherein the group 15 ions ions to be incorporated into the layer comprising the metal incorporated in the semiconductor material are selected from oxide. the group consisting of phosphide, arsenide, and nitride. 36. The method of claim 30, wherein the second material 22. The nanoparticle of claim 1, further comprising a layer precursor composition contains a metal carboxylate com ofa third material disposed between the nanoparticle core and pound comprising metalions to be incorporated into the layer the layer comprising the second material. comprising the metal oxide material, and the conversion com 23. The nanoparticle of claim 22, wherein the third material prises reacting the metal carboxylate compound with an alco is a semiconductor material incorporating ions selected from hol compound. at least one of groups 2 to 16 of the periodic table. 24. The nanoparticle of claim 1, wherein the first material 37. The method of claim 25, wherein the metal is selected is the semiconductor material and the second material is the from group 8 of the periodic table. metal oxide material. 38. The method of claim 37, wherein the metal is iron. 25. A method for producing a nanoparticle comprising a 39. The method of claim 25, wherein the metal is selected core that comprises a first material and, thereover, a layer that from group 12 of the periodic table. comprises a second material, wherein one of the first and 40. The method of claim 39, wherein the metal is zinc. second materials is a semiconductor material incorporating 41. A nanoparticle comprising: ions from group 13 and group 15 of the periodic table and the a core that itself comprises a first material; and other of the first and second materials is a metal oxide mate thereover, a layer that comprises a second material, US 2010/0283005 A1 Nov. 11, 2010

wherein one of the first and second materials is a semicon sisting of ions from the transition metal group of the periodic ductor material and the other of the first and second table or ions from the d-block of the periodic table. materials is a metal oxide material incorporating metal 59. The nanoparticle of claim 41, further comprising a ions selected from any one of groups 1 to 12, 14, and 15 layer of a third material disposed between the nanoparticle of the periodic table. core and the layer comprising the second material. 60. The nanoparticle of claim 41, wherein the first material 42. The nanoparticle of claim 41, wherein the metal is is the semiconductor material and the second material is the selected from any of groups 5 to 10 of the periodic table. metal oxide. 43-44. (canceled) 61. A method for producing a nanoparticle comprising a 45. The nanoparticle of claim 41, wherein the metal is core that comprises a first material and, thereover, a layer that selected from group 8 of the periodic table. comprises a second material, wherein one of the first and 46. (canceled) second materials is a semiconductor material and the other of 47. The nanoparticle of claim 45, wherein the group 8 the first and second materials is an oxide of a metal selected metal is iron. from any of groups 3 to 10 of the periodic table, the method 48. The nanoparticle of claim 47, wherein the iron oxide comprising the steps of has a formula selected from the group consisting of Fe0. forming the core; and Fe2O, and FeO. thereupon depositing, on the core, the layer comprising the 49. The nanoparticle of claim 48, wherein the iron oxide is second material. Y-Fe-O. 62. The method of claim 61, wherein the core has a com 50. The nanoparticle of claim 41, wherein the semiconduc position, formation of the core comprising (i) effecting con tor material incorporates ions selected from at least one of version of a nanoparticle core precursor composition to the groups 2 to 16 of the periodic table. composition of the nanoparticle core, and (ii) growing the COC. 51. (canceled) 63. The method of claim 62, wherein the precursor com 52. The nanoparticle of claim 50, wherein the ions include position comprises first and second core precursor species at least one member of the group consisting of zinc, cadmium, containing ions to be incorporated into the growing nanopar and mercury. ticle core, the first and second core precursor species being 53. The nanoparticle of claim 50, wherein the ions include separate entities in the core precursor composition, the con at least one member of the group consisting of boron, alu version being effected in the presence of a molecular cluster minium, gallium, and indium. compound under conditions permitting seeding and growth 54. (canceled) of the nanoparticle core. 55. The nanoparticle of claim 50, wherein the ions include 64. (canceled) at least one member of the group consisting of Sulfur, sele 65. The method of claim 62, wherein the precursor com nium, and tellurium. position comprises first and second core precursor species 56. The nanoparticle of claim 50, wherein the ions include containing ions to be incorporated into the growing nanopar at least one member of the group consisting of phosphide, ticle core, the first and second core precursor species being arsenide, and nitride. combined in a single entity contained in the core precursor 57. (canceled) composition. 58. The nanoparticle of claim 41, wherein the semiconduc tor material incorporates ions selected from the group con