Simulating High‐Efficiency, Lead‐Free Inorganic‐Organic Perovskite Tandem Solar Cells with over 46% Efficiency

Abstract Perovskite‐based tandem solar cells (SCs) show significant potential for improving efficiency. In this study, three configurations were designed and optimized: a top cell (ITO/ZnSe/CH 3 NH 3 GeI 3 /CuSCN/Ni), a bottom cell (ITO/ZnSe/CH 3 NH 3 SnI 3 /CuI/Ni), and a tandem cell combining both. Using SCAPS‐1D, the study evaluated how the absorber layer thickness, doping concentration, and defect density affected photovoltaic (PV) performance. It also explored the influence of doping in the back surface field (BSF), interface defect densities, temperature, and back contact work function. The top cell achieved a power conversion efficiency (PCE) of 28.47%, with an open‐circuit voltage (V OC ) of 1.21 V, a short‐circuit current density (J SC ) of 27.17 mA/cm 2 , and a fill factor (FF) of 86.24%. The bottom cell reached a PCE of 18.46%, with a V OC of 0.83 V, a JSC of 27.17 mA/cm 2 , and an FF of 81.839%. The optimized tandem structure demonstrated a notably higher efficiency of 46.89%, with a J SC of 27.17 mA/cm 2 , a V OC of 2.04 V, and an FF of 84.31%. These results suggest the proposed CH 3 NH 3 GeI 3 /CH 3 NH 3 SnI 3 tandem design could pave the way for efficient, eco‐friendly, and cost‐effective PV cells in a near future.