Coupling-Assisted Renormalization of Excitons and Vibrations in Compressed MoSe₂–WSe₂ Heterostructure

Vertical heterostructures (HSs) constructed with two-dimensional (2D) materials is expected to generate fascinating properties due to interlayer coupling between neighboring layers. However, interlayer coupling can be easily obscured by cross-contamination during transfer processes, rendering their experimental demonstration challenging. Here, we explore the coupling-assisted renormalization of excitons and vibrations in a mechanically fabricated MoSe 2 –WSe 2 HS through high-pressure photoluminescence, Raman spectra, and density functional theory calculations. Accompanied by the interlayer coupling enhancement, the excitonic and vibrational renormalizations involving dimensionality and composition variations were achieved. A cycle of 2D–3D–2D excitonic evolution was disclosed and pressure-induced emergence of X – exciton of MoSe 2 in HS was found reflecting the band structure transition in the MoSe 2 –WSe 2 HS. The Raman spectra reveals that the coupled A 2 ″ vibrations of WSe 2 and MoSe 2 in HS was stiffened and out-of-plane A 1 ′ vibrations of WSe 2 and MoSe 2 in HS got coherent upon pressure modulation. This coupling-assisted renormalization in MoSe 2 –WSe 2 HS can be extended to other 2D layered HSs, which indicates the possibility to design a flexible HS with controlled excitonic and vibrational system for light-emitting diodes, excitonic, and photovoltaic devices.