Investigation of novel all-inorganic perovskites Ba3PX3 (X = F, Cl, Br, I) with efficiency above 29%

Lead-free inorganic halide perovskites, specifically Ba3PX3 (X = Cl, F, I, Br) have gained attention in green photovoltaics due to their remarkable mechanical, optical, structural, and electronic properties. Using first-principles calculations, we investigated the mechanical, electronic, and optical characteristics of Ba3PX3, revealing direct band gaps at the Gamma-symmetry point, assessed with the PBE and HSE functionals. The charge distribution analysis shows strong ionic bonding between Ba and halides and covalent bonding between P and halides. The perovskites exhibit desirable optical properties, including high absorption in the visible-UV range, making them ideal for optoelectronic devices. Furthermore, SCAPS-1D simulations on Ba3PF3, Ba3PCl3, Ba3PBr3, and Ba3PI3-based solar cells with the SnS2 ETL layer revealed power conversion efficiencies of 23.15%, 16.13%, 21.63%, and 29.89%, respectively. Consequently, the Ba3PI3 compound shows significant potential as an absorber in solar cells based on the SnS2 ETL layer in the near future.