Regulation of electronic structure of monolayer MoS2 by pressure

Understanding pressure-regulated electronic properties is crucial for integrating two-dimensional semiconductors into flexible electronic devices and pressure sensors. We thoroughly explored the tunability of the electronic structure of monolayer MoS2 upon the application of perpendicular pressure and shear stress by using first-principles calculations. The band gap increased at low pressures and then decreased as the pressure increased. Variations in the band gap are caused by the combined interaction of the increasing and decreasing trends in the band gap. The increase in the band gap is induced by the enhancement of the p-d orbital interaction at the top of the valence band (TVB). The delocalization of charge and unstable hybridization bonding causes a reduction in the band gap. The band gap under perpendicular pressure modes is closely related to the structural variation. Shear stress can effectively reduce the band gap with minimal change to the crystal structure. The maximum point at the TVB and the minimum point at the bottom of the conduction band are different for all pressure modes, resulting in various anisotropic properties. This study provides a theoretical basis for modulating the electrical and optical properties of monolayer MoS2.