Anion replacement effect on the physical properties of metal halide double perovskites Cs2AgInX6 (X=F, Cl, Br, I)

This article is about structural, electronic, optical and thermoelectric properties of metal halide double perovskites Cs2AgInX6 (X = F, Cl, Br, I). These properties are computed using the highly accurate full potential linearized augmented plane wave method based of density functional theory. To acquire suitable ground state lattice parameters, generalized gradient approximation has been used. The calculated structural parameters are found in excellent agreement with the available literature. In addition, modified Becke-Johnson potential is taken into account for precise calculation of band structures. These structures discover the direct semiconducting nature of investigated compounds, however, value of the band gap decreases from F to I anion replacement. As consequences, the optical absorption edge shifts toward lower energies. To further evaluate physical behavior, thermoelectric properties such as Seebeck coefficients, thermal conductivities, electrical conductivities and figure of merits are also calculated. This study specifies present double perovskites as probable candidates for optical and thermoelectric devices.