Controlling Orientation, Morphology and Optical Properties of Alkylamine / Metal-Sulfide Nanoparticles Thesis submitted in partial fulfilment of the requirements for the degree of “DOCTOR OF PHILOSOPHY” by Alexander Rabkin Submitted to the Senate of Ben-Gurion University of the Negev June 2015 Beer-Sheva Controlling Orientation, Morphology and Optical Properties of Alkylamine / Metal-Sulfide Nanoparticles Thesis submitted in partial fulfillment of the requirements for the degree of “DOCTOR OF PHILOSOPHY” by Alexander Rabkin Submitted to the Senate of Ben-Gurion University of the Negev Approved by the advisor _______________ Approved by the Dean of the Kreitman School of Advanced Graduate Studies ________________ June 2015 Beer-Sheva II This work was carried out under the supervision of Prof. Yuval Golan In the Program for Interdisciplinary Ph.D. in Nanotechnology Ben-Gurion University of the Negev III Research-Student's Affidavit when Submitting the Doctoral Thesis for Judgment I Alexander Rabkin, whose signature appears below, hereby declare that: I have written this Thesis by myself, except for the help and guidance offered by my Thesis Advisors. The scientific materials included in this Thesis are products of my own research, culled from the period during which I was a research student. This Thesis incorporates research materials produced in cooperation with others, excluding the technical help commonly received during experimental work. Therefore, I am attaching another affidavit stating the contributions made by myself and the other participants in this research, which has been approved by them and submitted with their approval. Date: 29/11/2015 Student's name: Alexander Rabkin Signature:______________ IV Collaborator’s Affidavit Regarding the Paper Named: "Surface Plasmon Resonance in Surfactant Coated CuS Nanoparticles: Role of the Structure of the Capping Agent" I Ofir Friedman, whose signature appears below, hereby declare that: I have collaborated with the author of this thesis and our advisor on the work entitled "Surface Plasmon Resonance in Surfactant Coated CuS Nanoparticles: Role of the Structure of the Capping Agent" during my period in Yuval Golan’s research group as a 4th year engineering project student. During this period, the author of this thesis acted as my co-advisor for the project and has overseen my work. Therefore, while I was involved in every part of this work, my part of the work was supervised and overseen by Alexander Rabkin in every aspect. I hereby declare that while I am indicated as an equal contributor in this paper, I will not be using the content thereof as original results in any future Thesis I will compose. Date: _________________ Collaborator's name: Ofir Friedman Signature:______________ V Acknowledgements My special thanks to my advisor, Prof. Y. Golan for his guidance and continuous support throughout my studies. I thank Prof. J. Israelachvili, Dr. N. Belman, Dr. L. Meshi, S. Samuha, M. Genkin, O. Friedman and R. E. Abutbul for invaluable discussions and cooperation. I thank Dr. V. Ezersky and Dr. Y. Kalisman for expert assistance in TEM. The help of Dr. D. Mogilyanski with XRD is highly appreciated. I thank Dr. A. Miliontshick for assistance with TGA and DSC measurements and Dr. S. Kolusheva with flourimetry measurements. Additional thanks to Dr. M. Bar-Sadan for the use of her UV-Vis-NIR spectrophotometer. My special thanks to the members of Prof. Yuval Golan’s research group: Dr. A. Upcher, Dr. A. Osherov, Dr. M. Shandalov, Dr. S. Sengupta, T. Safrani, M. Biton, K. Petel, O. Friedman, R.E. Abutbul and T. Tempelman. The greatest gratitude I would like to address to my family for their support. VI Dedication This Thesis is dedicated in memory of the late Yotam Zmiri, who assisted during the initial work on CuS nanoparticles as an engineering project student. VII Table of Contents 1 Introduction and Scientific Background ............................................................... 1 1.1 Nanoscale Semiconductors ............................................................................ 1 1.1.1 Quantum Size Effect ................................................................................ 1 1.1.2 Surface Trap States in Semiconductors ..................................................... 2 1.1.3 Localized Surface Plasmon Resonance (LSPR) ........................................ 3 1.2 Metal Sulfide Nanoparticles ........................................................................... 4 1.2.1 CdS Nanoparticles ................................................................................... 4 1.2.1.1 CdS Nanoparticle Photosensitivity .................................................... 5 1.2.2 PbS Nanoparticles .................................................................................... 6 1.2.3 CuS Nanoparticles ................................................................................... 7 1.2.3.1 Surface Plasmon Resonance in CuS Nanoparticles ............................ 8 1.3 Alkylamine Surfactants .................................................................................. 8 1.4 Nanoparticle-Surfactant Interactions in Surfactant Assisted Synthesis .......... 10 1.5 Metal Chalcogenide Nanoparticle Synthesis from Alkyl Xanthate Precursors in Alkylamines .......................................................................................... 14 2 Experimental Details ......................................................................................... 16 2.1 Materials ...................................................................................................... 16 2.2 Metal Ethylxanthate Synthesis ..................................................................... 16 2.3 ODA/HDA-coated Metal Sulfide Nanoparticles Synthesis ........................... 17 2.4 Directed Assembly (DA) of PbS Nanoparticles on ODA/HDA Sheets ......... 18 2.5 Illumination, UV Irradiation and Dark Storage of CdS Nanoparticles........... 18 2.6 H2S Release Measurement from Illuminated CdS Nanoparticle Suspensions 18 2.7 Thermal Treatment of CuS Nanoparticles .................................................... 19 2.8 Characterization Methods ............................................................................ 19 2.8.1 Transmission Electron Microscopy (TEM), High Resolution TEM (HR- TEM) and Analytical TEM (ATEM) ................................................ 19 2.8.2 Powder X-Ray Diffraction (XRD) .......................................................... 20 2.8.3 Atomic Force Microscopy (AFM) .......................................................... 20 2.8.4 Optical Absorbance ................................................................................ 20 2.8.5 Fluorescence .......................................................................................... 20 2.8.6 Thermal Gravimetric Analysis (TGA) .................................................... 21 2.8.7 Differential Scanning Calorimetry (DSC) ............................................... 21 VIII 3 General Review of the Thesis Articles ............................................................... 22 4 Relationship between the Articles ...................................................................... 24 5 Results ............................................................................................................... 26 5.1 Directed Coassembly of Oriented PbS Nanoparticles and Monocrystalline Sheets of Alkylamine Surfactant ............................................................... 26 5.2 Time, illumination and solvent dependent stability of cadmium sulfide nanoparticle suspensions ........................................................................... 27 5.3 Surface Plasmon Resonance in Surfactant Coated CuS Nanoparticles: Role of the Structure of the Capping Agent ........................................................... 28 6 General Discussion ............................................................................................ 29 6.1 Crystallization of Monocrystalline AA Surfactant Sheets from Metal Sulfide Nanoparticle Suspensions ......................................................................... 29 6.1.1 Synthesis and Arrangement of PbS Nanoparticles on AA Sheets ............ 29 6.1.2 Crystallization of ODA Monocrystalline Sheets from CdS Nanoparticle Suspensions ...................................................................................... 32 6.1.3 Application of DA method to CuS Nanoparticle Suspensions ................. 34 6.2 Storage Conditions Effect on Nanoparticle Properties .................................. 35 6.2.1 Dry Storage Compared to Storage in Suspension .................................... 35 6.2.2 Storage Sensitivity to Temperature and Air ............................................ 36 6.3 The 2D Surface Structure of ODA and its Transformation ........................... 38 7 Directions for Future Work ................................................................................ 41 8 Conclusions ....................................................................................................... 43 9 References ......................................................................................................... 45 Appexdix A – Synthesis of SnS nanoparticles ......................................................... 51 IX List of Figures Figure 1.1: Schematic illustration of the energy level structure in NC and bulk semiconductors. ...................................................................................................