CASTEP investigation of structural, electronic, and optical properties of halide perovskites RbXCl₃ (X = Ge, Sn, Pb) for solar cell applications

This work aims to test the structural, electronic, and optical properties of RbXCl₃ (X = Ge, Sn, Pb). The presented discussion is reported through the Cambridge Assembly Serial Total Energy Package (CASTEP) based on density functional theory (DFT). DFT with the Generalized Gradient Approximation GGA correlational function and ultra-soft pseudo potential (PBE) is reported. RbGeCl₃, RbSnCl₃, and RbPbCl₃ are in the cubic phase. The calculated band gaps of RbGeCl₃, RbSnCl₃, and RbPbCl₃ are 1.03, 1.07, and 2.13 eV, respectively. The finding of a band gap is very well corroborated by the existing data. The band structures are further evaluated by partial density of state (PDS) and total density of state (TDOS). The partial and total density of states confirms the degree of localization of electrons. Optical properties were discussed in detail with the hypothetical dielectric function. It has been found that the dielectric function exhibits a wide range of energy transparency concerning its dielectric function. Materials were found to be effective in absorbing ultraviolet light, and having narrow band gaps which may be used for optoelectronic and solar cell appliances.