Numerical analysis of the MASnI₃/CZT(Se_1−xS_x) interface to boost the performance via band offset engineering

This study investigates a tin-based perovskite solar cell (PSC) incorporating an inorganic hole transport layer, examined through simulations with the SCAPS simulator. The chosen CuZnSn(Se_1−xS_x) compound emerges as a promising candidate for the hole transport layer, allowing for a tunable band gap via adjustments to the S/(S + Se) ratio. The band gap varies from 0.95 eV for Cu₂ZnSnSe₄ to 1.5 eV for Cu₂ZnSnS₄, achieved through strategic valence band offset engineering at the MAPbI₃/CuZnSn(Se_1−xS_x) interface. However, achieving an optimal Valence Band Offset (VBO) at MASnI₃/CuZnSn(Se_1−xS_x) remains challenging yet crucial for realizing high-performance Perovskite Solar Cells. The device efficiency is systematically optimized by manipulating the S content, resulting in a noteworthy Power Conversion Efficiency of 18.29%. Furthermore, it is uncovered that a carefully selected VBO (0.22 eV) is achieved with the CZTSe_0.4S_0.6 hole transport layer, contributing significantly to the improved performance of the PSC. These findings underscore the importance of precise engineering in achieving optimal device properties for advanced solar energy conversion applications.