Figure 4.

Variation in the PL intensity in the heterobilayer and a schematic representation of the band structure under strain. The dependence of the WS₂ to MoS₂ PL intensity ratio in the heterobilayer under (a) tensile and (b) compressive strains. The intensity ratio is monotonically increased and decreased under tensile and compressive strain, respectively. A schematic representation showing the contrasting trends of the evolution of electronic band structure in monolayers of MoS₂ and WS₂ under (c) tensile (red) and (d) compressive (blue) strain. “direct” and “indirect” represent the direct semiconducting characteristic and direct to indirect transition, respectively.