Dynamic tuning of exciton hybridization and dipole moments in trilayer WSe₂ by the hydrostatic pressure

Pressure is an efficient tuning knob for dynamically modulating the interlayer separation and coupling in van der Waals materials. The multilayer transition metal dichalcogenides (TMDs) that feature strong light-matter interactions and spin-valley locked superlattices provide a versatile platform for studying the effects under hydrostatic pressures. Here, through the measurements of reflectance contrast spectra at low temperatures, we systematically investigate trilayer WSe₂ devices in a diamond anvil cell (DAC) with the ability to dynamically control the pressures and electric fields. The intralayer exciton energy exhibits small blue shifts, attributed to an increase of the interlayer hopping parameter. More intriguingly, electric field dependences of the optical response reveal that the dipole moments of interlayer excitons decrease at a rate of ~ 7% per GPa. Meanwhile, we observe a boost of the coupling strength between intra- and interlayer excitons, reaching approximately three times the value at ambient conditions when subjected to a pressure of 6.3 GPa. Our results establish that the excitonic transitions and interactions can be effectively manipulated by the hydrostatic pressure, opening new avenues for exploring many-body physics and engineering new functional optoelectronics in 2D van der Waals heterostructures.