Unveiling the potential of lead-free Cs2AgBi0.75Sb0.25Br6 double perovskite solar cells with multilayer charge transport for 30% efficiency

The present study delves into the utilization of computer modeling techniques to analyze a photovoltaic (PV) design incorporating a lead (Pb)-free perovskite absorber material. This innovative structure employs a cesium-based double perovskite material, specifically Cs2AgBi0.75Sb0.25Br6, characterized by an energy bandgap of 1.80 eV. The Cs2AgBi0.75Sb0.25Br6 exhibits a range of advantageous properties, including heightened stability in ambient conditions and appropriately aligned bandgaps. Given these considerations, an extensive exploration of the FTO/CdS/Cs2AgBi0.75Sb0.25Br6 /HTL/Au configuration was undertaken to assess the impact of ten distinct hole transport layers (HTLs) on the solar cell's efficiency. The simulation and analysis of all devices were conducted employing the one-dimensional SCAPS-1D (Solar Cell Capacitance Simulator) tool. Furthermore, the efficiency of the FTO/ETL/Cs2AgBi0.75Sb0.25Br6 /MoO3/Au architecture was probed, employing six different electron transport layers (ETLs) (BaSnO3, PC61BM, SnS2, Ti2O3:Nb, CdS, ZnOS), to discern the optimal combination. Post-optimization, adjustments were made to the absorber and ETL thickness, as well as the acceptor doping and defect density of the absorber, and the donor and defect density of the ETL, for the six combinations assessed. These topologies were also examined for their impacts on series and shunt resistance, capacitance, the Mott-Schottky effect, generation and recombination processes, current–voltage density, and quantum efficiency. Eventually, the most efficient cell in this study achieved a power conversion efficiency (PCE) of 30.30 % and featured the FTO/ZnOS/Cs2AgBi0.75Sb0.25Br6/MoO3/Au configuration. The aforementioned findings hold significant potential for advancing lead-free, double perovskite solar cells (PSCs) that are both more efficient and environmentally sustainable, paving the way for their widespread adoption in the future.