Theoretical Investigation of a new Double Perovskites of Rb₂CuSbZ₆ (Z = F, Br, and I) for Sustainable Technologies

The present investigation thoroughly evaluates the structural, optoelectronic, elastic, and transport properties of Rb₂CuSbZ₆ (where Z = F, Br, and I). The assessment includes the application of the Born-Huang criterion, the tolerance factor, and the formation energy to ensure the thermodynamic, structural, and mechanical stability of the compounds. Analysis of elastic and mechanical parameters supports their ductile nature and directed bonding capabilities. Utilizing the Tran and Blaha-modified Becke-Johnson approximations, the study estimates the band gap values of Rb₂CuSbF₆, Rb₂CuSbBr₆, and Rb₂CuSbI₆ as 1.37 eV, 0.72 eV, and 0.36 eV, respectively, indicating characteristics of indirect bandgap semiconductors. Extensive scrutiny of optical parameters reveals remarkable dielectric and absorption capabilities within the visible light spectrum. Consequently, Rb₂CuSbZ₆ (where Z = F, Br, and I) double perovskites are recommended for utilization in solar cell applications and optoelectronic devices. Furthermore, assessments of their transport properties indicate that the examined compounds display attributes of a p-type semiconductor, alongside an exceptionally low thermal conductivity and a high power factor, making them highly suitable for energy harvesting devices.