Systematic study of optoelectronic and thermoelectric properties of new lead-free halide double perovskites A2KGaI6(A = Cs, Rb) for solar cell applications via ab-initio calculations

Abstract

The variant perovskites are considered novel materials for studying solar cells and other electro-optic applications. Born’s stability criteria confirm the mechanical stability, while Poisson coefficient (ν > 0.26) and Pugh ratio (B0/G > 1.75) certify the ductile nature of the compounds by investigating elastic properties. For Cs2KGaI6 and Rb2KGaI6, the computed bandgap is direct 1.81 eV and 1.85 eV, respectively, in terms of exploring the band structures. Their band gaps may capture electromagnetic waves in the visible spectrum, excelling themfor solar cell devices. The optical properties have been studied against photon energy (eV) with maximum transition and absorption in the visible region. BoltzTrap code is employed for the thermoelectric properties executed by electrical conductivity, thermal conductivity, power factor, and figure of merit (ZT), which shows a slight variation in the temperature. Hence, the considered lead-free double perovskite compounds offer applications in solar cell devices and p-type semiconducting behavior predictive in transport investigations.