Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemistry

Supervisor

Dr. Zhifeng Ding

Abstract

Solar cell development has been a focus in energy research, with light-absorbing layers as the key theme. Copper indium disulphide (CuInS2) and copper zinc tin sulphide (Cu2ZnSnS4 or CZTS) have energy band gaps that are optimal for solar energy conversion. New preparation methods have been developed with practicality, safety, and low costs in mind. The one-pot method developed in this thesis group has been utilized to create nanocrystals that can be used to absorb light and generate current. The use of low temperatures and minimalistic reaction conditions has led to the production of CIS and CZTS nanocrystals that can be made into thin films. In this work, many analytical methods were used to investigate the physical and chemical nature of the synthesized CIS and CZTS nanocrystals to ensure purity and photoactivity. A layer-by-layer approach was used to confirm the optimal configuration for a solar cell physically and chemically. The quality of CIS and CZTS films were assessed by factors such as the production of photocurrent, the band gap, and interfacial chemical reactions. The solar cell layers were examined using a variety of physical, electrochemical and analytical methods in order to determine the effects of the synthesis and deposition on established properties. The electrochemistry of the interface was examined using photoelectrochemical measurements and intensity modulated photocurrent spectroscopy was also performed at the interface to identify relative reaction rates of the photoprocesses. X-ray absorption near-edge, X-ray photoelectron, X-ray diffraction and Raman spectroscopies examined the physical aspects of the films. Insight into the transfer of photogenerated electrons and effects of surface morphology can be elucidated through the combination of these techniques. A systematic approach towards the development of these nanocrystal-based solar cells consisting of CIS or CZTS has shown great progress towards creating low-cost photovoltaics.

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