Investigation of Cu-based nanoparticles for photovoltaic applications

• Main Author: Hanria, Samuel.
• Other Authors: School of Materials Science and Engineering
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering::Materials::Energy materials
• Online Access: http://hdl.handle.net/10356/49016
• Institution: Nanyang Technological University

Colloidal semiconductor nanocrystals (NCs) have proven to possess great potential in solar-harvesters and light-emitters applications due to their interesting tunable optical properties based on quantum-confinement effects. They can be conveniently processed, easily handled, and deposited on any substrates. Specifically ternary I-III-VI2 materials have been the research focus of developing thin film solar cells as its optical band gap energy well matches with optimal solar spectrum range for photovoltaic application. There were 2 studies reported in this manuscript. Firstly, tetragonal-structured CuInS2 nanocrystals have been succesfully synthesized using simple inexpensive thermal decomposition method. Reaction with several indium precursors was executed, and it was found that indium acetylacetonate produced the well balanced stoichiometry and anisotropic polycrystals. These 20 nm crystals grew from thin nanoplates into thick nanoplates. Other than XRD, FESEM and TEM imaging, characterization techniques employed also in this study were UV-Vis spectroscopy, Raman spectroscopy, and photocurrent measurement. It was found that presence of other phases or species also formed and contributed to its optical properties. Second study involved the coalescence of two dissimilar inorganic materials that can be triggered at room temperature by means of electrostatic interaction between nanoparticles. CuSe was coated with anionic polymer, while In2S3 with cationic polymer. To date, there has never been a study conducted in this area. This is important as it would give control over the stoichiometry of CuIn(SexS1-x)2 film which has interesting optical properties as light absorber materials. Effect of pH was studied by titration of the sample dispersions with diluted NaOH. Also, ability of polymer coating to induce coalescence was investigated by adding varying concentration of cationic PDAC into series of fixed concentration of CuSe nanoparticles.