Electronic Structure, Optical Properties, and Potential Applications of n-BN/WS2 (n=1 to 4) Heterostructures

摘要

In contrast to bulk semiconductors, the bandgap of two-dimensional (2D) transition-metal dichalcogenide monolayers is strongly dependent on the dielectric environment. The optical properties of these 2D materials can also be significantly modified by substrate screening. We report herein the structural, electronic, and optical properties of n-BN/WS2 heterostructures consisting of a WS2 monolayer on top of n layers of BN substrates (n = 1 to 4) based on first-principles calculations and theoretical analysis. The results reveal that the bandgap of the n-BN/WS2 heterostructures decreases with increasing number of dielectric layers in the environment, while the band edge is enhanced. The 1-BN/WS2 heterostructure with one layer of BN is apt for photocatalytic water splitting applications. The imaginary part of the dielectric function also shows that the n-BN/WS2 layers exhibit semiconductor properties. As the number of layers is increased, the static dielectric constant increases. The n-BN/WS2 layers also exhibit optical anisotropy. These results suggest a pathway to engineer the bandgap of 2D materials via substrate choice.