DFT Analysis of Structural, Elastic and Optoelectronic Enhancements in LiGeCl₃ Under Pressure for Photovoltaic Applications

This study focuses on the crystalline lithium-based perovskite material, LiGeCl₃, with a view to improving its structural, elastic, electronic and optical properties by exploiting the effect of hydrostatic pressure. Combining density of states (DOS and PDOS) analysis with DFT and GGA approximation results, it is shown that the application of pressure reduces the lattice parameter, enhancing self-cohesion and stabilising the atomic structure. At ambient pressure, LiGeCl₃ exhibits semiconducting properties with a direct band gap, dominated by the p-orbitals of Cl atoms in the valence band and Ge in the conduction band. Under increasing pressure (0 to 6 GPa), the band gap is progressively reduced until it disappears at 6 GPa, leading to an electronic transition from a semiconducting to a metallic state. This transition results from the compression of the crystal lattice, which intensifies orbital interactions and causes the valence and conduction bands to overlap. In addition, pressure significantly enhances the optoelectronic properties of LiGeCl₃, including absorption in the visible spectrum, spectral reflectivity and refractive index, making the material more suitable for photovoltaic applications. These results highlight the potential of LiGeCl₃ in engineering advanced materials for semiconductor and optoelectronic devices, while demonstrating the crucial role of hydrostatic pressure as a tool for modulating material properties