Pressure-Dependent Light Emission of Charged and Neutral Excitons in Monolayer MoSe.

Tailoring the excitonic properties in two-dimensional monolayer transition metal dichalcogenides (TMDs) through strain engineering is an effective means to explore their potential applications in optoelectronics and nanoelectronics. Here we report pressure-tuned photon emission of trions and excitons in monolayer MoSe via a diamond anvil cell (DAC) through photoluminescence measurements and theoretical calculations. Under quasi-hydrostatic compressive strain, our results show neutral (X) and charged (X) exciton emission of monolayer MoSe can be effectively tuned by alcohol mixture vs inert argon pressure transmitting media (PTM). During this process, X emission undergoes a continuous blue shift until reaching saturation, while X emission turns up splitting. The pressure-dependent charging effect observed in alcohol mixture PTM results in the increase of the X exciton component and facilitates the pressure-tuned emission of X excitons. This substantial tunability of X and X excitons in MoSe can be extended to other 2D TMDs, which holds potential for developing strained and optical sensing devices.