First-principles investigation of mechanical and optoelectronic performance of halide double perovskites Rb ₂ LiScX ₆ (X=Cl, Br, I) for energy harvesting

Halide double perovskites (HDPs) based on Rubidium are becoming progressively more renowned as ecologically friendly, thermally stable and structurally stable semiconductors for energy harvesting and UV-based optoelectronics. This work implemented density functional theory and the WIEN2K code to examine the phase configuration, electrical, optical and elastic traits of a new lead-free HDPs, Rb 2 LiScX 6 (X[Formula: see text]Cl, Br, I). The materials were constituted to crystallize in a fixed cubic configuration, with lattice constants increasing from Rb 2 LiScCl 6 to Rb 2 LiScI 6 because of halogen size effects. The stability of materials in terms of cubic phase and thermodynamics is validated by the tolerance factor and formation enthalpy. The calculated direct band gaps of 4.59[Formula: see text]eV (Rb 2 LiScCl[Formula: see text], 3.64[Formula: see text]eV (Rb 2 LiScBr[Formula: see text] and 2.58[Formula: see text]eV (Rb 2 LiScI[Formula: see text] suggest encouraging UV absorption characteristics. Optical analysis indicates significant absorption in the UV region and high dielectric constants, especially for Rb 2 LiScI[Formula: see text] The analysis of mechanical parameters confirms mechanical stability and anisotropy. These results identify Rb 2 LiScX 6 compounds as robust, lead-free materials with excellent optoelectronic and mechanical properties for future optoelectronic technologies.