A study of ultra-thin Cu_xS-Cd_yZn_1-yS polycrystalline solar cells

The study of ultra-thin polycrystalline thin films for use in solar cells is an area of significant research importance because of the low cost of materials. This advantage, however, is often off-set by the rather complex structural properties resulting in inferior photovoltaic performance. This work examines the effects of substrate film thickness of Cu_xS-Cd_yZn_1-yS chemically sprayed thin film solar cells and analyses the results based on a simple structural model previously proposed by Kwok (1978). It was observed that for cells made on very thin substrates, leakage effect apparently dominated the photovoltaic characteristics resulting in rather low photovoltaic outputs. When the film thickness was increased to above 4.5 mu m, the cell properties were mostly influenced by the junction profile and the surface properties. This would result in a significantly reduced open-circuit voltage. Both effects were apparently structure dependent.