First-Principle Study of the Structural, Electronic, and Optical Properties of Cubic Cesium Lead Halide Perovskites for Photovoltaic System

Lead halide perovskites have attracted considerable attention as optoelectronic materials because these materials have high photovoltaic conversion efficiency. The current study is based on Density Functional Theory (DFT). This theory was used to calculate the structural, optical, and electronic properties of the lead halide perovskites CsPbX3 (X = Chlorine (Cl), Bromine (Br), Iodine (I)) compounds . In order to calculate the above mentioned properties of cubic perovskites CsPbX3 (X = Cl, Br, I), Full Potential Linear Augmented Plane Wave (FP-LAPW) method was implemented in conjunction with DFT utilizing LDA, GGA-PBE and mBJ approximations. A good agreement was found between experimentally measured values and theoretically calculated lattice constants. These compounds have a direct and wide band gap located at the point of R-symmetry, while the band gap decreases from ‘Cl’ to ‘I’ down the group. The densities of electrons revealed a strong ionic bond between Cs and halides and a strong covalent bond between ‘Pb’ and (Cl, Br, and I). The dielectric functions (reflectivity, refractive indices, absorption coefficients), optical conductivities (real and imaginary part) and other optical properties indicated that these compounds have novel energy harvester applications. The modeling of these perovskite compounds shows that they have high absorption power and direct band gaps in visible ultraviolet range and it also shows that these compounds have potential applications in solar cells.