Structural Stability and Electronic and Optical Properties of Bulk WS2 from First-Principles Investigations

Tungsten disulfide (WS2) has attracted great attention for use in optoelectronics due to its suitable bandgap and adjustable properties. However, the structure and photoelectric properties of bulk WS2 are not well understood. The first-principles method is applied herein to study the structural stability and electronic and optical properties of WS2. Two phases, viz. hexagonal and rhombohedral, are considered. The results reveal that the two bulk WS2 phases are thermodynamically and dynamically stable based on the enthalpy of formation and phonon dispersion. The structural stability of WS2 is attributed to the S–W–S sandwich structure. The calculated bandgap of hexagonal and rhombohedral WS2 is 1.552 eV and 1.488 eV, respectively, indicating that WS2 is semiconducting. The calculated optical properties show that WS2 exhibits excellent adsorption capacity for ultraviolet light, whether in the hexagonal or rhombohedral structure.