Computational Design and Optimization of a Novel Non‐Toxic KGeI ₃ ‐Based All‐Inorganic Perovskite Solar Cell Using DFT and SCAPS‐1D

ABSTRACT The lead‐free perovskite solar cell (PSC) based on inorganic A‐site cation potassium (K) has recently gained significant attention. This study focuses on the solar cell capacitance simulator (SCAPS‐1D) simulation of lead‐free KGeI 3 perovskite absorber layer, which has a trigonal crystal structure. The simulation methodology is validated by replicating an experimentally fabricated CsPbI 3 PSC, achieving excellent agreement between the simulated and experimental characteristics. Applying this validated model to the novel KGeI 3 PSC system, various electron transport layers (ETLs) and hole transport layers (HTLs) are screened to determine the optimal device architecture. The effect of different layer thickness, doping, and defect density, series and shunt resistance, back metal contact, and temperature on the device performance is also being analyzed. The WS 2 and CuO are found to be the optimum ETL and HTL material. The optimized device structure is FTO/WS 2 /KGeI 3 /CuO/Ni with a power conversion efficiency (PCE) of 22.17%, fill factor (FF) of 81.86%, open circuit voltage ( V OC ) of 1.022 V, and short circuit current density ( J SC ) of 26.48 mA/cm 2 , respectively. Furthermore, the device demonstrates promising thermal stability, maintaining performance at elevated temperatures. This study demonstrates the strong potential of trigonal‐KGeI 3 perovskite for developing efficient, stable, and non‐toxic perovskite solar cells in the future.