Substrate effects on the properties of few-layer MoS2 and the MoS2/WS2 heterostructure from first-principles GW*

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are important materials in optoelectronic applications, in which these 2D materials are often placed on suitable substrates. As a result, the electronic and optical properties of TMDs can be modulated by the various substrates that they are deposited on. Here, we focus on the effect of two commonly used substrates in experiments – hexagonal boron nitride and gold – on three systems: monolayer MoS2, bilayer MoS2, and the MoS2/WS2 heterostructure. To reduce the computational cost, we employ the first-principles dielectric embedding GW to capture the dielectric effect of the substrate, which leads to a quantitative agreement with existing experiments. We further discuss the strengths and weaknesses of different approaches in describing the substrate effect.