Highly efficient 25.562% Cs2AgBiBr6 double perovskite solar cell with copper barium tin sulfide and ZnO as charge transport channels: an intuition from a theoretical study using SCAPS-1D

Halide perovskite solar cells have become a subject of interest in the photovoltaic domain due to their low cost and simple fabrication methodology. However, the presence of poisonous lead and stability issues have hampered their viability for commercialization. The advent of lead-free double perovskite such as Cs2AgBiBr6 has attracted significant attention. We modeled and analyzed a lead-free perovskite solar cell (PSC), based on Cs2AgBiBr6 with various charge transport layers, to obtain the most efficient configuration with the architecture FTO/ZnO/Cs2AgBiBr6/CFTS/Au. The device presents a power conversion efficiency (PCE) of 15.652%, fill factor (FF) of 62.926, current density (Jsc) of 22.085 mA/cm2, and open circuit voltage (Voc) of 1.126 V. After a comprehensive optimization of layer parameters to include the thickness of the electron transport layer (ETL) and absorber, ETL doping concentration, hole transport layer (HTL) and absorber, defect density of absorber, ETL/absorber and absorber/HTL, and ETL electron affinity, the following optimal values were obtained: 0.04 and 0.4 μm, 1018, 1022 and 1019 cm−3, 1014, 1010 and 1010 cm−2, and 4.0 eV. The final optimized PSC with the aforementioned optimal layer values shows a PCE of 25.562%, FF of 89.958%, Jsc of 19.978 mA/cm2, and Voc of 1.422 V. This performance demonstrates a 38.768% enhancement in PCE over the unoptimized device. The effects of operating temperature, work function of indium tin oxide (ITO), and metal back contact, alongside series resistance and shunt resistance, were evaluated on the optimized device. The resulting metric data obtained from our studies were compared with previously documented literature and showcase the study’s contributions in exploring alternative non-toxic, inorganic perovskite solar photovoltaics (PV), with potential to serve as a steering tool for PV advancement.