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 MoSe2–WSe2 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 MoSe2 in HS was found reflecting the band structure transition in the MoSe2–WSe2 HS. The Raman spectra reveals that the coupled A2″ vibrations of WSe2 and MoSe2 in HS was stiffened and out-of-plane A1′ vibrations of WSe2 and MoSe2 in HS got coherent upon pressure modulation. This coupling-assisted renormalization in MoSe2–WSe2 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.