New lead-free double perovskites A2NaInI6 (A = Cs, Rb) for solar cells and renewable energy; first principles analysis

The conversions of light energy and heat energy into electrical energy are the leading source of renewable energy and extensively studied from the last decade. Therefore, we have explained structural, elastic, optical, and thermal properties A2NaInI6 (A = Cs, Rb) by density functional theory based Wien2K code. Computations of spin–orbit coupling (SOC) for speculating the precise bandgap and association of with SOC and without SOC is established. Poisson ratio and Pugh's ratio for both compounds in this study endorsed the character of ductility. The direct gaps for (Cs/Rs)2NaInI6 are 1.111 eV/1.121 eV calculated which are essential for solar cells. The optical properties are examined for optical properties. Large absorption coefficients in the near-visible region for both compounds certify that these compounds are suitable solar cells. Thermoelectric properties and figure of merit (ZT) systematically evaluated in the temperature range of 200–800 K.