Inorganic Lead‐Free Cs2AuBiCl6 Perovskite Absorber and Cu2O Hole Transport Material Based Single‐Junction Solar Cells with 22.18% Power Conversion Efficiency

Abstract Cs 2 AuBiCl 6 is considered to be a potential lead‐free double perovskite alternative for perovskite solar cells. Its electronic and optical properties are investigated using density functional theory. The electronic properties of Cs 2 AuBiCl 6 material ensure a bandgap of 1.40 eV (without considering SOC) and 1.12 eV (with SOC) using mBJ exchange‐correlation functional, close to the optimal bandgap for solar cell application as per the Shockley–Queisser limit. Optical properties suggest a high absorption coefficient ≈10 5 cm −1 with low reflectance, making it the optimal absorber material. Furthermore, the photovoltaic performance of Cs 2 AuBiCl 6 based single‐junction transparent conducting oxide (TCO)/IDL1/Cs 2 AuBiCl 6 /IDL2/Cu 2 O solar cell is investigated using SCAPS‐1D device simulation program. The impact of electron affinity, thickness, carrier concentration, defect density, and interface defect density is examined using interface defect layer (IDL) on the photovoltaic performance. The maximum photoconversion efficiency (PCE) of ≈22.18% is noticed for optimized material's parameters. These studies on TCO/IDL1/Cs 2 AuBiCl 6 /IDL2/Cu 2 O solar cell will provide guidelines for designing and developing an efficient lead‐free perovskite‐based solar cell as an alternative to conventional halide perovskite materials based solar cell.