Optimizing CuInSe₂ solar cells with kesterite-based upper absorber and back surface field layers for enhanced efficiency: a numerical study

Abstract This study explores the performance enhancement of an innovative multi-layer solar cell structure using the SCAPS-1D (Solar Cell Capacitance Simulator in One Dimension) software. We aim to improve the efficiency of a solar cell structure comprising ZnO/ZnSe/CZTSe/ CuInSe 2 /CZTSSe/Mo by incorporating CZTSe as the upper absorber layer, CuInSe 2 as the main absorber layer, and CZTSSe as a back surface field layer. Initially, we compare the performance of three different configurations by analyzing their J–V characteristics. For the best performing structure, we further examine the external quantum efficiency spectrum. We then evaluate various window (ZnO, ZnMgO, SnO 2 , Zn 2 SnO 4 ) and buffer (ZnSe, ZrS 2 , SnS 2 , In 2 S 3 ) materials, identifying ZnO and ZrS 2 as the most effective for achieving high current density and efficiency. Through detailed simulations, we determine the optimal thicknesses for CZTSSe (0.2 µ m), CZTSe (0.4 µ m), and CuInSe 2 (3.2 µ m). Additionally, by optimizing the acceptor density to 10 20 cm −3 , we significantly enhance the performance of both CZTSe and CZTSSe layers. Temperature management is shown to be crucial, with the highest efficiency observed at 300 K. As a result of these optimizations, the solar cell structure achieves a remarkable efficiency of 35.38%. Furthermore, we compare our results with existing literature to highlight the advancements made in this study. These findings underscore the importance of material selection and structural optimization in developing high-efficiency solar cells and provide a framework for future advancements in photovoltaic technology.