First-principles study on the electronic and optical properties of WS2 and MoS2 monolayers

This study explores the electronic and optical properties of WS2 monolayer using first-principle calculations based on density functional theory. Results show that WS2 monolayer demonstrates large absorption coefficient and photoconductivity and high refraction index in the visible light range. Generally, the optical properties of WS2 monolayer are considerably similar to those of MoS2, although approximately 0.2 eV ultraviolet-shift has been found in the visible light range. This result indicates that WS2 monolayer can also be extensively used as an efficient optical material similar to MoS2 monolayer. The mechanism of the optical properties is explored using the density of state and the partial density of state. (C) 2017 Published by Elsevier B.V. on behalf of The Physical Society of the Republic of China (Taiwan).