Design and Performance Evaluation of Lead-Free Cesium Gold Bismuth Chloride Perovskite Solar Cells with Tunable Transport Layers

All-inorganic double perovskites, such as cesium gold bismuth chloride (Cs 2 AuBiCl 6 ), have emerged as stable and environmentally friendly alternatives to lead-based perovskites. The Solar Cell Capacitance Simulator (SCAPS-1D) was used in this study to simulate a planar perovskite solar cell using absorber Cs 2 AuBiCl 6 . To enhance the device performance, different electron transport materials (ZnSe, 6,6-phenyl C 61 butyric acid methyl ester (PC60BM), SrTiO 3 (STO), CeO 2, CdS, and indium gallium zinc oxide (IGZO)) and hole transport materials (TiS 2, TaS 2, NiS 2, HfS 2, CuSbS 2, and MoS 2 ) were investigated. The work systematically examines the influence of material selection on photovoltaic characteristics, including current density–voltage ( J–V ) and quantum efficiency (QE) responses, layer thickness, defect states, interface defects, and doping concentration. Among the evaluated structures, the configuration with ZnSe as the electron transport material (ETM) and NiS 2 as the hole transport material (HTM) demonstrated the highest performance, yielding a V oc of 0.7669 V, J sc of 42.679 mA/cm 2, a fill factor (FF) of 81.13%, and a power conversion efficiency (PCE) of 26.56%. Furthermore, the optimized double perovskite achieves competitive efficiencies with TiS 2 reaching 26.03%, TaS 2 reaching 25.83%, HfS 2 reaching 25.85%, CuSbS 2 reaching 19.47%, and MoS 2 reaching 26.20%. These findings highlight Cs 2 AuBiCl 6 as a promising lead-free absorber for achieving high efficiency, stability, and sustainability in next-generation perovskite solar cells.