A comparative study of different buffer layers for CZTS solar cell using Scaps-1D simulation program

In this work, we have optimized a CZTS-based solar cell using solar cell capacitance simulator (SCAPS-1D). We particularly focused on replacing the buffer layer, which is conventionally CdS-based, with a non-toxic and abundant material. To this end, we have made a comparative study with 3 materials (CdS, SnS2, Zn2SnO4) by evaluating the photovoltaic parameters (Short-circuit current density, open circuit voltage, Fill Factor and efficiency) as a function of the buffer layer thickness. We also studied the effect of the active layer thickness on the performance of the cell, in correlation with different materials used for buffer layer elaboration. We concluded that SnS2 is the best candidate to replace CdS, which was considered until now the most suitable material. We thus obtained an efficiency of 12.73% with the structure glass/Mo/CZTS/SnS2/ZnO by avoiding any toxic product and by reducing the thickness of buffer layer to 50 nm.