DFT Insights into Mechanical, Vibrational, Electronic, and Optical Properties of Bulk WSe₂ Dichalcogenide

The elastic, vibrational, and electro-optical properties of WSe₂ using the first-principles approach have been explored in this study. The lattice parameters of WSe₂ are consistent with the available results. The structural stability of WSe₂ has been proven by satisfying the stability conditions and from the phonon dispersion spectra. According to the elastic constants and moduli, WSe₂ is a material with a high level of machinability, rather soft, mechanically and elastically anisotropic, and brittle in nature. The relatively lower values of the thermodynamic parameters suggest that WSe₂ could be an excellent option as a thermal barrier coating (TBC) material. The overlap of the acoustic and optical modes of phonons in the lower frequency region is responsible for the enhancement of the anharmonicity of the crystal and hence reduces the thermal conductivity. WSe₂ is an indirect band gap material with band gap values 0.88 (LDA) and 1.329 eV (sX-LDA) with small values of carrier effective mass. Therefore, WSe₂ could be a potential candidate for electronic device applications. The optical investigation revealed that the material has a high refractive index, dielectric constant, and absorption coefficient, and considerable optical anisotropy. According to the reflectivity spectra, WSe₂ could be employed as an anti-reflection coating material. By examining the optical properties, it can be noted that WSe₂ is widely used to develop wave-guides, photonic devices, photovoltaic cells, and other optoelectronic devices.