Investigation of structural, electronic, optical and thermoelectric properties of hallide double perovskite Rb2AlAgX6 (X = Cl, I): A first-principles DFT study

Abstract

In order to meet the demands of the energy consumption, double perovskites (DP) are a dependable green energy source. Consequently, there is a great deal of promise for thermoelectric and optoelectronic device applications when studying these perovskite halides. Our work examined the thermoelectric and optoelectronic properties of Rb2AlAgCl6 and Rb2AlAgI6 halides using Density Functional Theory (DFT). The tolerance factor and energy of formation for the halides that were examined show that they are stable in the cubic phase, structurally and thermodynamically. We calculated the bandgaps for Rb2AlAgCl6 (Eg = 3.82 eV) and Rb2AlAgI6 (Eg = 1.321 eV) using mBJ potentials, and compared them to the reported values. The optical characteristics of the materials under investigation were revealed through the use of a complicated dielectric function. The computed optical findings show that the materials are suitable for optoelectronic applications, with maximal light absorption occurring in the ultraviolet (UV) and infrared (IR) ranges. Optical parameters obtained includes large values of absorption coefficients (∼105cm−1), low reflectivity (∼1–15 %), and high optical conductivity (∼1015 sec−1). Thermoelectric properties revealed enhanced power factor for Rb2AlAgI6 as compared to Rb2AlAgCl6. These results imply that these materials are appropriate for application in optical and thermoelectric devices.