Excitonic Evolution in WS₂/MoS₂ van der Waals Heterostructures Turned by Out-of-Plane Localized Pressure

In this study, we explore the exciton dynamics in a WS2/MoS2 van der Waals (vdW) heterostructure under varying pressures by integrating a laser-confocal photoluminescence (PL) spectroscope and an atomic force microscope (AFM). For the WS2/MoS2 heterostructure, the exciton emission belonging to MoS2 is too weak to be distinguished from the PL spectra. However, upon contact with a Si probe, the emission intensity of WS2 excitons significantly decreases from 34,234 to 6560, thereby matching the intensity level of MoS2. This alteration substantially facilitates the exploration of interlayer excitonic properties within the heterostructures using PL spectroscopy. Furthermore, the Si probe can apply out-of-plane localized pressure to the heterostructure. With increasing pressure, the emission intensity of the WS2 trions decreases at a rate twice that of other excitons, and the exciton energy increases at a rate of 0.1 meV nN−1. These results elucidate that the WS2 trions are particularly sensitive to the out-of-plane pressure within a WS2/MoS2 vdW heterostructure.