First‐principles investigation of <scp>Rb<sub>2</sub>Ag</scp>(Ga/In)Br<sub>6</sub> for thermoelectric and photovoltaic applications
Gourav Gourav, Mukaddar Sk, K. Ramachandran, Saurabh Ghosh
Abstract
Abstract In this article, we have systematically investigated the structural, electronic, optical and thermoelectric properties of Rb 2 Ag(Ga/In)Br 6 . The resulting negative formation energy along with the absence of imaginary phonon modes confirm the thermodynamic stability of Rb 2 Ag(Ga/In)Br 6 . In addition, the derived electronic properties by using GGA‐PBE + mBJ + SOC functional show that the direct band gap values are 1.21 eV and 1.42 eV for Rb 2 AgGaBr 6 and Rb 2 AgInBr 6 , respectively. Furthermore, the dispersed direct band nature of Rb 2 Ag(Ga/In)Br 6 leads to their outshining optical properties such as higher order (10 5 cm −1 ) absorption coefficient, appreciable optical conductivity, and low reflectivity. Moreover, the higher figure of merit values of Rb 2 Ag(Ga/In)Br 6 are resulted from their ultra‐low thermal conductivity and high electrical conductivity. Thus, Rb 2 Ag(Ga/In)Br 6 are predicted to be potential photovoltaic and thermoelectric materials.