Wrinkle and near-resonance effects on the vibrational and electronic properties in compressed monolayer MoSe.

Pressure has been considered as an effective technique to modulate the structural, electronic, and optical properties of transition metal dichalcogenide (TMDs) materials. Here, by performing in situ high pressure Raman, photoluminescence (PL) and absorption measurements, we systematically investigated the vibrational and electronic properties evolution of monolayer MoSe grown on a SiO/Si substrate under high pressure. When the pressure increased up to 4.84 GPa, an unexpected phonon mode at 367 cm appeared, which was identified as the Raman-inactive A'' mode and was activated under high pressure. Combined with the analysis of absorption spectroscopy, this phenomenon can be attributed to the pressure-induced wrinkle and near-resonance effects in compressed monolayer MoSe. Subsequently, A' split into two peaks after 7.44 GPa, providing further distinct evidence for the pressure-induced wrinkle effect in compressed monolayer MoSe. Moreover, this wrinkle effect can also lead to a rapid quenching of photoluminescence in monolayer MoSe. These results suggest that the substrate plays an important role in determining the vibrational and electronic properties of compressed monolayer MoSe, and can provide valuable information on the electronic and optoelectronic applications of monolayer MoSe under extreme conditions.