Theoretical modeling and optimization: Cd-free CTS/Zn(O,S)/ZnO thin film solar cell

Abstract Latterly Zn(O, S) has gained utmost attention as an eco-friendly buffer layer with controllable energy levels for high-performance thin-film solar cell (TFSCs) devices. The article discusses that the conventional detrimental Cd-containing buffer is replaced by the non-toxic Zn(O,S) buffer and yielded a comparable high efficiency. Using SCAPS software, the modeling and numerical simulations of the CTS based solar cell are systematically analyzed. Detail investigations of the band alignment between the CTS absorber and Zn(O, S) buffer layer has been studied as a function of the S/(S+O) ratio along with the effects of thickness, carrier concentration, defect density of buffer layer and absorber layer with interface defect density. The final optimized results of p-CTS/Zn(O,S)/n-ZnO/Al heterojunction revealed that the obtained figure of merit value is comparably high (ɳ=13.65%, VOC = 0.3802 V, JSC = 48.33 mA/cm2, and FF = 74.45%) than the previously reported values. All in all, the present study suggests that Zn(O, S) can be a suitable alternative candidate for the CdS-buffer layer in a CTS-based solar cell.