Tuning the exciton-phonon coupling in 2D vdW heterostructure by pressure

Van der Waals (vdW) heterostructures of 2D crystals opened a new platform to explore novel properties emerged from layer-layer interaction. For example, the interplay between electron correlations and atomic structure in Moiré superlattices can lead to exotic phenomena ranging from correlated insulators superconductor, and topological states. In addition to the electron interaction, the interlayer electron–phonon interaction is also ubiquitous in vdw heterostructure. In WSe₂-hBN heterostructures, optically silent hBN phonons could emerge in Raman spectra through resonant coupling to WSe₂ electronic transitions. Here, we demonstrate that such an interfacial exciton-phonon coupling could be tuned by pressure. In hBN sandwiched monolayer WSe₂, we observed a giant shift of the resonance of exciton-phonon complex, up to 150 meV, by applying hydrostatic pressure up to 5 GPa.