CdS Window Layer for Large Open Circuit Voltages of Low Environmental-Load CdS/CdTe Solar Cells

Abstract

AbstractThe low ‘environmental-load’ CdS/CdTe solar cells for reducing consumption of Cd compounds have been investigated employing the CdS layers fabricated at various substrate temperatures, TCdS, and a conversion efficiency of 14.1% has been achieved. The nanostructure of CdS crystallites made at different TCdS are compared to the crystallinity of CdS, and CdTe deposited on CdS as well as sulfur fraction in CdTe1-xSx mixed crystal layer unintentionally formed at CdS/CdTe(S) interface. The photovoltaic performances, especially obtained relative high open circuit voltages, are discussed in conjunction with the structural properties as well as electrical properties of the solar cells. The solar cells show a relative high Voc due to the large CdTe grains as well as the narrow depletion layer width. Besides, preventing deterioration of the CdS/CdTe(S) interface is found to be quite effective for achieving high open circuit voltages and fill factors.