First-principle analysis of optical and thermoelectric properties in alkaline-based perovskite compounds AInCl₃ (A = K, Rb)

This study utilized density functional theory (DFT) within Wien2K code to assess the physical characteristics of cubic halide perovskites AInCl(3) (A = Rb, K). Structural optimization was carried out using the generalized gradient approximation (GGA), and electronic properties were computed employing the modified Becke-Johnson potential (mBJ). The stability of these compounds was confirmed through formation energy calculations and phonon dispersion analysis, further supported by the determination of various elastic coefficients, demonstrating their mechanical stability and natural ductility. Furthermore, optical parameters such as refractive index, reflectivity, absorption coefficient, and loss functions were estimated and analyzed. Notably, transport properties were investigated for RbInCl3 and KInCl3. AInCl(3) (A = Rb, K) exhibited a high Seebeck coefficient and achieved the largest figure of merit, approximately 0.99, signifying their significant potential for thermoelectric applications.