Solar Cell Capacitance Simulator (SCAPS-1D-1D) Based Comparative Study of Lead and Lead-Free Perovskite Solar Cells: Performance Evaluation and Optimization

Tandem perovskite solar cells offer significant potential for achieving high power conversion efficiencies. Using Solar Cell Capacitance Simulator-1D (SCAPS-1D) numerical simulations, several device architectures were designed and optimized in terms of band gaps, layer thicknesses, doping concentrations, and defect densities. The FTO/TiO2/MAPbI3/Spiro-OMeTAD/Au cell achieved a PCE of 43.30% (Voc = 1.5766 V, Jsc = 30.20 mA/cm2, FF = 90.92%). The AZO/ZnO/MAPbI3/CIGS/Au configuration reached 36.21%, while the AZO/ZnO/MASnI3/CIGS/Au device delivered 35.51% efficiency. The best performance was obtained for the FTO/ZnO/MASnI3/CuSCN/Au structure, with a record simulated PCE of 43.71% (Voc = 1.4389 V, Jsc = 36.64 mA/cm2, FF = 85.25%). The exceptional efficiency is attributed to the synergistic combination of optimal band alignment, low defect density, and appropriate doping conditions. Nonetheless, these simulated values surpass current experimental efficiencies of Sn-based perovskites, emphasizing the gap between idealized models and practical realizations. This work provides clear guidelines for functional layer engineering and underscores the need for experimental validation to bridge this gap. The proposed ZnO/MASnI3/CuSCN tandem design represents a promising route toward efficient, stable, and lead-free perovskite solar cells.