Document Type

Thesis - University Access Only

Award Date

2012

Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Xingzhong Yan

Abstract

Cu2ZnSnS4 (CZTS) is considered a promising photovoltaic (PV) material due to its excellent material properties and abundance. Because of the similarity between CZTS iv and Cu(ln,Ga)Se2 (CIGS), many techniques successfully employed in the research and development of CIGS PV technology have been tried on CZTS thin film solar cells (TFSCs). CZTS TFSCs have been successfully fabricated by vacuum-based methods and nonvacuum-based methods, with vacuum-based methods such as evaporation and sputtering leading the CZTS PV technology. However, these techniques are either expensive or utilize toxic gases such as H2S. Therefore, non-vacuum-based and environmentally friendly deposition technologies are needed. The objective of this work was to develop environment-friendly solution-based processing to fabricate CZTS thin film solar cells. Solution-based processing provides a simple way to control the composition by tuning the molar concentration of reagents when preparing the CZTS solgel precursor. The effects of CZTS sol-gel precursor concentration, spin-coating speed, and annealing procedures were studied. UV-visible spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX or EDS), X-ray diffraction (XRD), Raman spectroscopy, and current-voltage characterization were employed to characterize CZTS thin films and CZTS solar cells. The results showed that the properties of CZTS thin films, especially the morphology, were highly dependent on deposition procedures. CZTS samples consisting of I μm crystals were obtained. The best cell in this work had an efficiency of 0.63% with an active area of 0.46 cm 2 . The relatively low efficiency was attributed to a high series resistance and low shunt resistance. Solution-based processing has the potential to produce cost-effective CZTS solar cells due to its simplicity and elimination of H2 S in the annealing process. However improvement in the efficiency of the CZTS solar cells is needed. This may come from optimizing the composition of CZTS thin films, optimizing the thickness of CdS layer, and developing other n-type thin films to form p-n junction with CZTS thin film.

Library of Congress Subject Headings

Solar Cells
Thin films
Photovoltaic power generations

Publisher

South Dakota State University

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Rights Statement

In Copyright