Formation of Photoconductive SnS Thin Films through Reaction of Sn-Metal Films in Sulfur-Vapor

SnS absorber layers of thickness 205–1060 nm were successfully prepared by sulfurization of sputtered Sn precursor films of thickness 100–500 nm in sulfur vapor from an elemental sulfur source. All these SnS thin films showed obvious photo current response and persistent photoconductivity effect. Photocurrent decay constants τ and β of the films of different thickness were obtained from the fitted functions for the decay in their photo current response curves. Effect of the thickness on the photo current decay slope (W(t)) was investigated. In addition, the relationship among τ, β, W(t) and the photovoltaic performance of SnS/i-a-Si/n-a-Si solar cells was investigated and discussed in different thickness of SnS absorber. The best results of an open circuit voltage (Voc) of 360 mV and short circuit current density (Jsc) of 2.4 mA/cm 2 were obtained for the cell with a thickness of 845 nm for SnS. It was found that the trend in the variation of τ and W(t) with the thickness of SnS films was well correlated with the change in Jsc, Voc, fill factor, and conversion efficiency of the cells with the thickness of SnS films.