Electronic, Optical and Thermoelectric Properties of Cs2XInCl6 (X = Ag, Na) Halide Double Perovskites

Herein, the optoelectronic, structural, thermoelectric, and elastic features of halide double perovskites (HDPs) Cs2XInCl6 (X = Ag, Na) are examined by using full-potential linearized augmented plane wave (FP-LAPW) technique. The generalized gradient approximation (GGA) and Tran-Blaha modified Becke-Johnson (TB-mBJ) potential are employed to figure out the features of the mentioned compounds. The computed values of direct band gaps (E-g) for Cs2AgInCl6 and Cs2NaInCl6 compounds are 2.52 and 5.24 eV, correspondingly. The stability of perovskites is confirmed in terms of formation energy Delta H-f, tolerance factor (tau), and octahedral factor. Furthermore, optical properties analysis demonstrates that the studied compounds exhibit conductivity and absorptivity across a broad range of incident photon energy with minimum R(omega). Moreover, outcomes of elastic parameters display isotropic and ductile nature for both materials. Thermoelectric (TE) properties like thermal conductivity (k/tau), power factor (PF), electrical conductivity (sigma/tau), and Seebeck coefficient (S) are also calculated by utilizing BoltzTrap code. Cs2NaInCl6 attains the maximum value of ZT (0.76) with PF of 0.42. Computed TE and optical parameters indicate that Cs2XInCl6 (X = Ag, Na) are promising for usages in solar absorbing and energy conversion devices.