ABSTRACT The increasing depletion of traditional energy resources requires the exploration for sustainable alternatives. This study provides a detailed investigation of lead‐free halide double perovskites Li 2 ScCuX 6 (X = F, Cl) using density functional theory (DFT) in the CASTEP code with GGA‐PBE functional and TB‐mBJ corrections. Structural optimization shows that both compounds are cubic and stable, with lattice parameters of 8.35 Å for Li 2 ScCuF 6 and 9.91 Å for Li 2 ScCuCl 6 . The negative formation energies of −2.217 eV/atom for Li 2 ScCuF 6 and −1.648 eV/atom for Li 2 ScCuCl 6 indicate their thermodynamic stability. Their Goldschmidt tolerance factors are 0.82 and 0.80, exhibiting structural stability. An electronic structure analysis shows that GGA‐PBE predicts metallic behavior for Li 2 ScCuF 6 , with a 0 eV bandgap, while Li 2 ScCuCl 6 is semiconducting with a bandgap of 1.874 eV. However, the more accurate TB‐mBJ correction reveals significant bandgaps of 1.10 eV for Li 2 ScCuF 6 and 1.76 eV for Li 2 ScCuCl 6 , demonstrating that both materials are semiconductors. Mechanical property assessment indicates ductile behavior with Pugh's ratios above 1.75, positive Cauchy pressures exhibiting ionic bonding, and anisotropic features. Optical characteristics represent of 4.58 (Li 2 ScCuF 6 ) and 4.07 (Li 2 ScCuCl 6 ), with Li 2 ScCuCl 6 indicating UV absorption (2.4 × 10 5 cm −1 at 4.90 eV) while Li 2 ScCuF₆ shows visible‐region activity. Phonon dispersion exhibit dynamical instability, while AIMD simulations at 300 K demonstrate dynamical stability. Thermodynamic analysis exposes higher Debye temperatures for the fluoride compound, exhibiting robust atomic bonding. These results establish Li 2 ScCuX 6 (X = F, Cl) perovskites as favorable candidates for next‐generation optoelectronic applications, UV photodetectors, and sustainable energy conversion materials.
Hussain et al. (Tue,) studied this question.