Lead-free novel perovskite Ba₃AsI₃: First-principles insights into its electrical, optical, and mechanical properties

Lead-free halide perovskites are a crucial family of materials in the fabrication of solar cells. At present, Solar cells are facing several challenges such as mechanical and thermodynamic instability, toxicity, unsuitable optical parameters, bandgap, and absorption coefficient. Ba₃AsI₃ is a halide perovskite which has demonstrated good efficiency and tremendous promise for usage in solar cell applications, and it offers a possible solution to these issues. In this study, the properties of the Ba₃AsI₃ perovskite solar cell were investigated using first-principles density functional theory (FP-DFT) calculations with the CASTEP (Cambridge serial total energy package) formulation. Most of its physical qualities, including its elasticity, electrical composition, bonding, optoelectronic characteristics, and optical characteristics have not yet been explored. In this work, these unexplored properties have been thoroughly investigated using density functional theory-based computations. The Born-Huang criterion and phonon dispersion characteristics have revealed that the material is mechanically stable. The bonding nature has been investigated using the density of states curves, Mulliken population analysis, and electronic charge density. Additionally, different elastic parameters demonstrate that Ba₃AsI₃ has reasonably high machinability and is mechanically isotropic. ELATE's three-dimensional visualization and optical properties also show isotropic behavior in all directions. The band structure shows that the bandgap is direct. Based on its direct bandgap, stability, large range of absorption coefficient, and suitable optical parameters, Ba₃AsI₃ is recommended as an absorber layer for solar cell fabrication in a near future.