First principles study of electronic, optical, and thermoelectric properties of K2Pd (Cl/Br)6 for solar cells and renewable energy

The vacancy-ordered double perovskites are extensively studied for solar cells and thermoelectric characteristics. Herein, the electronic, mechanical, optical, and transport characteristics of K2Pd(Cl/Br)(6) are addressed comprehensively. The structural, and dynamic stabilities are confirmed by tolerance factors (0.93, 0.95) and the positive frequencies of phonon band structures. The criteria for mechanical stability and elastic parameters ensure their stable, anisotropic, and ductile nature. The computation of band structures (BS) and density of states (DOS) show band gaps 2.0 eV, and 1.3 eV for K2PdCl6, and K2PdBr6, respectively. The optical properties are calculated by dielectric constants, absorption coefficient, and their dependent parameters. The K2PdBr6 has an ideal absorption band for visible light solar cells. The thermoelectric performance has been analyzed by figure of merit (ZT). The positive Seebeck coefficient p-type nature with significantly high ZT (0.73, 0.74) at room temperature.