Analysis of Predicted and Observed Current Densities in Antimony Sulfide Selenide Thin Film Solar Cells and Prospects for Efficiency Improvement

Abstract

FTO/CdS(100 nm)/Sb2SxSe3−x(455 nm)/C-Ag solar cells were prepared by thermal evaporation of Sb2S3 and Sb2Se3 powders, which gave antimony sulfide selenide absorbers A—Sb2S1.24Se1.76 and B—Sb2S0.44Se2.56. FTO is a commercial SnO2:F coating (7 Ω). Solar cells of A and B (area, 0.5 cm2) have conversion efficiencies 4.7 and 6.8%; with open circuit voltages, 0.496 and 0.418 V; and short-circuit current densities (Jsc), 20.8 and 31.5 mA cm−2. Thin films A and B have optical bandgap (Eg) of 1.40 and 1.29 eV and can lead to light generated current densities (JL) of 32 and 36 mA cm−2 for AM1.5G solar radiation. At finite thickness of 455 nm in the solar cells, the predicted JL for A and B are 27 and 33 mA cm−2, which set their observable Jsc maxima. The shortfall in Jsc in cell A is 23%, and in cell B, it is 4.5%. Under solar radiation (cells at 58 °C), Jsc is 19.8 and 28.2 mA cm−2 for A and B; and at 26 °C, 19.2 and 26.9 mA cm−2. In view of the high current densities typical of high efficiency solar cells, we discuss the prospects toward improving the conversion efficiencies of these cells.