Pressure-dependent optical and vibrational properties of monolayer molybdenum disulfide

Abstract

Controlling the band gap by tuning the lattice structure through pressure engineering is a relatively new route for tailoring the optoelectronic properties of two-dimensional (2D) materials. Here, we investigate the electronic structure and lattice vibrational dynamics of the distorted monolayer 1T-MoS (1T′) and the monolayer 2H-MoS via a diamond anvil cell (DAC) and density functional theory (DFT) calculations. The direct optical band gap of the monolayer 2H-MoS increases by 11.7% from 1.85 to 2.08 eV, which is the highest reported for a 2D transition metal dichalcogenide (TMD) material. DFT calculations reveal a subsequent decrease in the band gap with eventual metallization of the monolayer 2H-MoS , an overall complex structure-property relation due to the rich band structure of MoS . Remarkably, the metastable 1T′-MoS metallic state remains invariant with pressure, with the J , A , and E modes becoming dominant at high pressures. This substantial reversible tunability of the electronic and vibrational properties of the MoS family can be extended to other 2D TMDs. These results present an important advance toward controlling the band structure and optoelectronic properties of monolayer MoS via pressure, which has vital implications for enhanced device applications. 2 2 2 2 2 2 2 1g 2g 2 2