Theoretical investigation of electronic and optical properties of 2D transition metal dichalcogenides MoX2 (X = S, Se, Te) from first-principles

Abstract

To use the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method in density functional theory (DFT), we have calculated the electronic structure and linear optical properties of 2D Transition metal dichalcogenides (TMDs), MoX 2 (X = S, Se, Te). The predicted optical gap of MoX 2 monolayers are in good agreement with the available experimental and theoretical data. The real and imaginary parts of dielectric function, optical absorption coefficient, reflectivity and energy loss function are also discussed in details for two directions of applied external electric field ( E ‖ x and E ‖ z ). It is found that the dielectric functions are highly anisotropic in low energy range (below 9 eV) and becomes isotropic in high energy range (above 9 eV). The most promising feature of MoX 2 monolayers is high value absorption coefficient with a wide absorption spectrum making them very suitable material for solar cells and optoelectronic applications. Also, the wide band gap of TMDs which is thickness dependent makes them promising candidates for optoelectronic devices. The results of our systematic study are expected to guide the experimentalists to achieve suitable properties related to band gap modifications via optical absorption measurements at the nanoscale. • DFT calculation were performed on the electro-optical properties of MoX 2 monolayer. • The band-structure and the static dielectric constant agree well with available data in the literature. • The optical spectra are isotropic along two directions of polarization. • The most promising feature of MoX 2 monolayers is high value absorption with a wide absorption spectrum. • Our study guide the experimentalists to achieve suitable properties via optical absorption measurements at nanoscale.