Investigation of ultra wide bandgap Flouro-perovskite materials RBeF₃ (R[bond, double bond]K and Li) for smart window applications: A DFT study

The human body is affected by ultraviolet radiation because it can penetrate and harm bodily cells. Although skin cancer and early aging are consequences of prolonged exposure to ultraviolet (UV) rays, sun rays signify immediate excessive exposure. In this context, some structural, optical, electrical, and mechanical properties of the beryllium-based cubic fluoro-perovskite RBeF₃ (R[bond, double bond]K and Li) compounds are examined through the use of density functional theory (DFT) within generalized gradient approximation (GGA) using the Perdew-Burke-Ernzerhof (PBE) approximations (GGA-PBE). The compounds KBeF₃ and LiBeF₃ have space group 221-pm3m, and their lattice constants and volumes are (3.765, 3.566) Å and (53.380, 45.379) ų, respectively, based on their structural properties. Computed results indicate that the compounds' bandgaps are 7.35 eV and 7.12 eV, respectively, with an indirect nature for KBeF₃ and LiBeF₃. The properties of the band structure indicate that both compounds are insulators. The bonding properties of these compounds, RBeF₃, are a combination of covalent and ionic. Optical properties of the compounds are examined which reflect the light-matter interaction like reflectivity, conductivity, and absorption. These materials were likely very hard but brittle, based on a higher bulk modulus B from elastic features, the B/G ratio, Pugh's ratio, and Vickers hardness. The compound RBeF₃, as determined by the findings, is used as a UV protection and reflection layer for car and room windows.