Unveiling the Potential of Graphene‐Integrated CsSnCl3 Perovskite Solar Cells: A Numerical Simulation Study

This study investigates the numerical modeling of lead‐free CsSnCl 3 ‐based perovskite solar cells (PSCs) using Solar Cell Capacitance Simulator‐1D simulation. The device structure features TiO 2 as the electron transport layer and Cu 2 O as the hole transport layer. Key parameters such as absorber thickness, acceptor doping concentration, defect densities, electrode work function, and operating temperature are systematically optimized to improve performance. An ultrathin graphene (Grp) interfacial layer is introduced at the CsSnCl 3 /Cu 2 O interface, which enhances charge separation by reducing recombination and improving band alignment. The device efficiency increases from 23.18% (Au/Cu 2 O/CsSnCl 3 /TiO 2 /FTO) to 23.26% with Grp, further to 31.45% with optimized metal contact (W/Cu 2 O/CsSnCl 3 /TiO 2 /FTO), and finally reaches 31.52% by combining both strategies. This efficiency enhancement is attributed to structural optimization, Grp‐enabled interface passivation, and improved charge extraction via metal contact engineering. Although Grp thickness has a limited influence, its presence effectively suppresses recombination losses. The optimized device achieves a power conversion efficiency of 31.52%, open‐circuit voltage ( V oc ) of 1.25 V, short‐circuit current density ( J sc ) of 27.98 mA cm 2 , and fill factor of 89.56%. These findings highlight the potential of Grp interface engineering to boost the performance and stability of CsSnCl 3 PSCs.