Study of electronic, mechanical, optical, and thermoelectric properties of stable double perovskites Cs2K(Ga/In)I6 for solar cells renewable energy

Double perovskites are exceptional materials for thermoelectric and optoelectronic applications in pursuing green energy. In this study, a comprehensive analysis of Cs₂K(Ga/In)I₆ has been conducted, focusing on its mechanical, electronic, optical, and thermoelectric properties by using wien2k, BoltzTraP, ShengBTE, and Phonopy codes. The stability of these compounds has been ensured by considering the tolerance factor, formation energy, phonon spectra, and elastic constants. The elastic and thermophysical properties, including ductility, anisotropy, Debye temperature, and melting temperature, are reported to be noteworthy. The band gaps of Cs₂K(Ga/In)I₆, measured to be 1.92 and 2.08 eV, indicate the presence of absorption bands in both the visible and ultraviolet regions. Significant absorbance, polarization, low optical reflectivity, and energy loss have been discussed in relation to photovoltaic applications. In addition, the transport characteristics are examined by analyzing the Seebeck coefficient and thermal and electrical conductivities. Due to their high figure of merit and exceptionally low lattice thermal conductivity at room temperature, these materials are highly recommended for thermoelectric generators.