Twist-driven wide freedom of indirect interlayer exciton emission in MoS2/WS2 heterobilayers

Summary: Theoretical and first-principal studies involving twisted two-dimensional (2D) heterobilayer transition metal dichalcogenides (TMDs) predict interlayer exciton (ILE) emission energy amplitudes (the energy difference between the lowest and the highest ILE emission energies) in the range of 100–260 meV. This can be translated into an interfacial exciton periodic potential modulation depth of 100–260 meV. However, experimental studies on twisted TMD heterobilayers have reported only a narrow depth of ILE emission of up to ∼70 meV. Here, we report a wide degree of freedom twist-angle-driven indirect ILE emission in chemical vapor deposition (CVD)-grown MoS2/WS2 vertical heterobilayers (up to ∼10%, amplitude of 120 ± 30 meV). This is attributed to the close interlayer spacing between MoS2 and WS2 courtesy of their similar hexagonal crystal symmetry with an almost similar size, coupled with interlayer spacing tuneability at various twist angles. The wide degree of freedom of ILE emission opens exciting avenues for exploring intriguing phenomena in tuneable twistronics