Performance Engineering of Cs ₂ AuScI ₆ Double Halide Perovskite Solar Cell: A DFT and SCAPS‐1D Approach to 31.82% Efficiency

ABSTRACT In response to pressing environmental priorities, the development of nontoxic and stable alternatives to lead‐based Perovskite solar cells is critical. This study focuses on Cs 2 AuScI 6 , a lead‐free Perovskite, as a promising photovoltaic material. Through density functional theory (DFT) calculations using Wien2k, a bandgap of 1.30 eV is revealed, with Au‐ d and Sc‐ d orbitals playing key roles in electronic properties and Au atoms dominating charge distribution. The material exhibits visible absorption peaks of the 10 5 order, indicating its potential for solar applications. Conducted by DFT, 36 configurations combining various electron transport layers and hole transport layers (HTLs) are investigated. Copper Barium Tin Sulfide (CBTS) is identified as the optimal HTL due to its alignment with the absorber material. Five standout device architectures of ITO/WS 2 /Cs 2 AuScI 6 /CBTS/Ni, ITO/ZnO/Cs 2 AuScI 6 /CBTS/Ni, ITO/TiO 2 /Cs 2 AuScI 6 /CBTS/Ni, ITO/PCBM/Cs 2 AuScI 6 /CBTS/Ni, and ITO/IGZO/Cs 2 AuScI 6 /CBTS/Ni (Where ITO means Indium Tin Oxide) achieved exceptional power conversion efficiencies of 31.48%, 31.46%, 29.44%, 28.75%, and 31.82%, respectively, surpassing the 18.61% efficiency of the ITO/C 60 /Cs 2 AuScI 6 /CBTS/Ni structure. The study further examines practical performance factors, including resistances, temperature effects, current–voltage ( J – V ) characteristics, and quantum efficiency, thereby enhancing its real‐world applicability. These findings highlight the potential of Cs 2 AuScI 6 as a nontoxic, inorganic alternative for perovskite solar technology, contributing to the sustainable development of photovoltaics.