First-principles calculations to investigate structural, electronic, elastic, optical and transport properties of halide double perovskites Cs2ABF6 (AB = BiAu, AgIr, CuBi, GaAu, InAs, InAg, InAu, InSb and InBi) for solar cells and renewable energy applications

Abstract

The first-principles calculations are used for a comprehensive study of the novel halide double perovskites by using the CASTEP code which is based on DFT. The correlational function of the GGA-PBE with the ultra-soft pseudo potential USP plane wave was utilized to carry out the present study. For all novel halide double perovskites, the lattice parameters were determined first, and the compounds were subjected to the mechanical stability criteria. From 0.56 to 4.99 eV, the Cs2ABF6 materials are found to be direct band-gaps. The dielectric functions of the materials of interest are large near and in the middle ultraviolet regions. They become smaller in the far and extreme ultraviolet regions. Furthermore, the Cs2ABF6 are found to be elastically stable, ductile, anisotropic and relatively low hard materials. A comprehensive analysis of the optoelectronics and thermoelectric nature with a given band gaps are carried out. This reflects the use of Cs2ABF6 in solar cells, energy storage devices, photovoltaic devices, radiation detectors, photonic crystals, light emitting diodes and thermoelectric generators. Thermoelectric coefficients such as the figure of merit thermal and electrical conductivities, Seebeck coefficient (S), and are also examined to check the possibility of these materials in the field of thermoelectric. The computed value of ZT reflects (ZT ∼ 1) Cs2ABF6 materials and reveals that such type of materials holds a virtuous route toward thermoelectric applicability.