Physical properties of alkali metals-based iodides via Ab-initio calculations

Abstract

Methods based on density functional theory are used to evaluate the thermodynamic, mechanical, optoelectronic and thermoelectric properties of the alkali metal-based iodides: XGeI3 (X = K, Rb and Cs). The thermodynamic stability of these compounds is checked by negative formation energy, and mechanical stability tested through tensor analysis of Chapin's method. For optoelectronic and thermoelectric properties, the recently developed modified Becke–Johnson potential is applied for accurate analysis of bandgap values. The optical properties are explored in terms of dielectric constants and refraction, while thermoelectric properties are explained by electrical and thermal conductivities, Seebeck coefficient, power factor and figure of merit scale. The narrow bandgap, high value of light absorption in the visible region and thermoelectric efficiency make XGeI3 prospective materials for renewable energy applications.