New Double Perovskite Solar Cell Containing Ba ₃ PCl ₃ (A ₃ BX ₃ ) and CsSnI ₃ (ABX ₃ ) Leading to an Improved Efficiency Above 30%

Abstract In photovoltaic (PV) technology, halide perovskites stand out for their exceptional optical properties, improved performance, and cost‐effectiveness. This study utilized SCAPS‐1D to examine a novel dual absorber solar cell, using Ba 3 PCl 3 as the top absorber and CsSnI 3 as the bottom absorber, marking the first comprehensive analysis of this pairing. The research thoroughly investigated the thickness, doping concentrations, and defect densities of each absorber to evaluate their impact on electrical properties such as V OC , J SC , FF, and power conversion efficiency (PCE). Additionally, the study meticulously analyzed the effects of temperature, shunt, and series resistances. The results show that the first device (FTO/SnS 2 /Ba 3 PCl 3 /Au) achieved a PCE of 17.75%, while the second device (FTO/SnS 2 /CsSnI 3 /Au) reached a PCE of 20.63%. Optimized designs combining both absorbers (FTO/SnS 2 /Ba 3 PCl 3 /CsSnI 3 /Au) resulted in a PCE of 30.97%, with a J SC of 47.52 mA/cm 2 , FF of 80.42%, and V OC of 0.81 V. These promising findings offer valuable insights for the future development of experimental solar devices.