Improving CZTS/ZTO solar cell efficiency with inorganic BSF layers

Copper zinc tin sulfide (CZTS) thin-film solar cells have garnered significant attention in the solar energy sector. This study aims to enhance the performance of CZTS solar cells by replacing the conventional, toxic CdS buffer layer with Z n 1 − x S n x O (ZTO) for x = 0.2. Utilizing the one-dimensional solar cell capacitance simulator (SCAPS-1D) and informed by experimental data on the physical properties of the solar cell layers, we investigated the effects of thickness, doping density, and defect density of the CZTS absorber layer on the cell’s performance. Initially, an efficiency of 14.76% was achieved. To improve this efficiency, an inorganic back surface field (BSF) layer was incorporated to mitigate charge carrier recombination at the absorber/back contact metal interface. Various materials, including CuO, C u 2 O , Mo S 2 and Mo S e 2 , were evaluated as potential BSF layers. Comparative analysis indicated that the inclusion of the BSF layer significantly enhances the solar cell efficiency, achieving up to 27% with C u 2 O as the BSF material. Furthermore, the study included an analysis of temperature effects and parasitic resistances to comprehensively assess the solar cell’s performance.