Prospecting K₂InLiX₆ (X = Cl, Br, I) double perovskite for photovoltaic and optoelectronic applications: a DFT-based analysis

This work presents a theoretical investigation of double halide perovskites K₂InLiX₆ (X = Cl, Br, I), aiming to advance their technological applications. In this context, K₂InLiX₆ (X = Cl, Br, I) compounds were comprehensively investigated in detail via density functional theory to explore their structural, mechanical, and optoelectronic characteristics. The investigated materials were observed to be dynamically, thermodynamically, and elastically stable. Structural analysis indicates an increase in lattice parameters and cell volume with larger halide substitution, whereas the tolerance factor and their positive phonon frequencies confirm structural and dynamical stability. All three compounds were found to have direct band gaps, with their values varying as the halogen at the “X” site is replaced. Mechanical evaluation confirmed that the titled compounds satisfy stability criteria while exhibiting anisotropic and ductile characteristics. An inclusive analysis of optical spectra, comprising dielectric functions, absorption coefficient, refractive index, and optical conductivity, reveals strong absorption, high conductivity, and low reflectivity. Overall, it is concluded that K₂InLiX₆ (X = Br, I) materials are promising for solar cells, while all the studied materials are valuable for photovoltaic and optoelectronic applications.