Coupling and Interlayer Exciton in Twist‐Stacked WS₂ Bilayers

Interlayer electronic and mechanical couplings of transitional metal dichalcogenides due to Van der Waals force determine their band structure and Raman modes evolution, respectively. Twist‐stacked WS 2 bilayers have been synthesized with twist angles of 0°, 13°, 30°, 41°, 60°, and 83° via chemical‐vapor depositon, which allows us to study the coupling effect by Raman and photoluminescence spectroscopy and density function calculation. The photoluminescence property implies that these random‐twisted WS 2 bilayers behave as quasi‐direct bandgap material due to weakened interlayer coupling as a result of larger interlayer distances than the nontwisted 0° and 60° stacked WS 2 bilayers (with an indirect band gap). In addition, an additional small peak (A I ) near the excitonic transition peak (A) is observed from the twisted bilayers, which can be attributed to the interlayer exciton transition.