Strain control of the electronic structure in WS2 homobilayers with 0° and 60° stacking angles

Two-dimensional transition metal dichalcogenides combine attractive semiconductor properties with exceptionally strong light-matter interaction. Their mechanical robustness allows the modulation of their optical and electronic functionalities via strain. Bilayers introduce the stacking angle as an additional parameter, whose role in the strain response is still elusive. Here, we combine differential reflectance spectroscopy and density functional theory calculations to explore the strain response of WS2 homobilayers with 0 degrees and 60 degrees stacking angles. The change of the excitonic resonance energies and linewidths depends on the stacking angle, highlighting the scope for the manipulation of the electronic structure of two-dimensional semiconductors via the synergistic harnessing of the strain and angle control parameters.