Unveiling the multifunctional potential of K₂YCuX₆ (X=Cl,Br): Structural, mechanical and optical insights for renewable energy frontiers

This study investigates the structural, electronic, optical and mechanical properties of K 2 YCuX 6 ([Formula: see text]) using advanced density functional theory (DFT) within the full potential linearized augmented plane wave (FP-LAPW) framework. Structural stability was validated through tolerance factor calculations, yielding values of 0.96 and 0.97 for K 2 YCuCl 6 and K 2 YCuBr 6 , respectively, while formation energy analysis confirmed thermodynamic stability with values of [Formula: see text]1.71 and [Formula: see text]1.73[Formula: see text]eV/atom. Mechanical stability was ensured by satisfying the Born criteria. Elastic anisotropy was revealed from anisotropic factor which is found to be 1.71 and 1.73 for K 2 YCuX 6 ([Formula: see text]). Electronic structure analysis revealed direct band gaps of 2.18[Formula: see text]eV for K 2 YCuCl 6 and 1.84[Formula: see text]eV for K 2 YCuBr 6 , attributed to significant p,d-hybridization between Cu-3d and halogen-p orbitals. Optical properties exhibited strong absorption across the visible and ultraviolet regions, with absorption coefficients exceeding 10 5 [Formula: see text]cm[Formula: see text]. Collectively, the findings demonstrate the multifunctional nature of K 2 YCuX 6 ([Formula: see text]), establishing them as strong candidates for next-generation solar cells and optoelectronic devices.