Mechanical, optoelectronic and thermoelectronic properties of double perovskites halides Rb2TCl6 [T = V, Cr, Mn] for optoelectronics and thermoelectronic applications

Recent research studies have generated stable lead-free inorganic double perovskites halides (A2TX6), replacing Pb2+-containing compounds' risky and unstable structures. The current study thoroughly examines the mechanical, optoelectronic, and thermoelectronic properties of the three perovskites halides Rb2TCl6 (T = V, Cr, Mn) in order to explore their potential applications. The FP-LAPW within the Wien2k computational code was used to apply the generalized gradient approximation (GGA) in the frame of density functional theory (DFT) in order to elucidate the above properties of Rb2TCl6. By using the Charpin and BoltzTraP techniques, we calculated and analyzed the mechanical parameters and thermoelectric properties of Rb2TCl6, respectively. Additionally, the cubic elastic constants as well as their derivative parameters meeting the ductile nature range were used to validate the durability of the studied materials. The formation energy results indicate that all Rb2TCl6 compounds exhibit mechanical and thermodynamic stability. According to this study, the change of cationic T-site from V to Cr to Mn is mainly responsible for the production of half-metallic (HM) and semiconductor nature in Rb2TCl6. Moreover, the GGA-PBE calculations successfully provided accurate direct band-gaps for the HM (Eg = 2.128 eV; T = V) and (Eg = 2.111 eV; T = Cr) and semiconductor (Eg = 1.2640 eV in spin-up and Eg = 1.7010 eV in the spin-down; T = Mn). The calculated optical parameters reveal that the three Rb2TCl6 perovskites demonstrate decent optoelectronic efficiency combined with high conductivity and absorption. These results reveal that perovskites halides are useful materials and candidates for spintronics and optoelectronics devices. Furthermore, the present study elucidates that the temperature-dependent nature of the thermoelectronic properties is due largely to their amazing electronic structures. These Rb2TCl6 materials may find wide use in thermoelectric applications, as evidenced by the ideal value of their calculated figure of merit (ZT = 1.0).