A Deep Analysis and Enhancing Photovoltaic Performance Above 31% with New Inorganic RbPbI3‐Based Perovskite Solar Cells via DFT and SCAPS‐1D

Abstract The inimitable structural, electronic, and optical properties of inorganic cubic rubidium‐lead‐halide perovskite have obtained significant attention. In this research, novel rubidium‐lead‐iodide (RbPbI 3 )‐based perovskite solar cells incorporating Tin Sulfide (SnS 2 ) is investigated as an efficient buffer layer, utilizing both Density Functional Theory (DFT) calculations and SCAPS‐1D simulator. Primarily, DFT is used to compute the bandgap, partial density of states (PDOS), and optical properties of the RbPbI 3 absorber, which are then applied in the SCAPS‐1D simulator. An optimized Al/FTO/SnS 2 /RbPbI 3 /Au device is systematically studied. Additionally, the effect of various influencing factors are investigated such as layer bulk defect density, interface defect density, doping concentration, and thickness. The highest power conversion efficiency (PCE) of 31.11% is achieved for the SnS 2 Electron Transport Layer (ETL), with a J SC of 32.47 mA cm −2 , V OC of 1.10 V, and FF of 87.14% for the Al/FTO/SnS 2 /RbPbI 3 /Au structure. Characteristics of quantum efficiency (QE) are also analyzed. Therefore, SnS 2 ETL demonstrates the robust potential for utilization in high‐performance photovoltaic cells based on RbPbI 3 perovskite.