The optimized of tunable all-inorganic metal halide perovskites CsNBr

We report the study of chemical and physical characteristics of all-inorganic metal halide perovskites CsNBr3 (N2+ = Ge, Sn, Pb) via implementation of first-principles approaches in the framework of density functional theory (DFT) methodologies. Three different DFT approximations include Perdew–Burke–Ernzerhof (PBE), PBESOL, and Wu-Cohen (WC) within the generalized gradient approximation (GGA) based on the full-potential linearized augmented plane-wave (FPLAPW) scheme are used in unification with Kohn–Sham (KS) equation as executed in WIEN2k package. In addition, the hybrid functional (HSE06) was utilized to reproduce accurate energy-gaps (Egap) in the PBE-band-structures of CsNBr3 perovskites. It is found that the present results of GGA approaches for structural, electronic, and optical properties are consistent with the existing experimental and previous DFT data, where PBE gives values closer to experiments than others. Nonmagnetic and semiconducting properties, with reliable Egap localized at the R-symmetry point, are revealed by the three GGA results of band structures and density of states for all CsNBr3 perovskites. Moreover, the photonic energy-dependent optical properties of CsNBr3 perovskites comprising the real and imaginary parts of the dielectric function, conductivity, reflectivity, refractive index, and absorption and extinction coefficients have been realized using the GGA approaches. The semiconducting direct Egap (Egap = 0.9814–1.9086 eV) and high optical absorption implies that the three cesium bromide perovskites CsNBr3 can utilize in designing inorganic photovoltaic (PV) solar cells, photodetectors, photodiodes, and other PV devices working in ultraviolet–visible range