Strain effects on electronic states and lattice vibration of monolayer MoS2

•First-principle calculation is conducted to study the strain effects on the electronic states and lattice vibration of monolayer MoS2.•It is illustrated that the strain-sensitive ππ bond-like interaction between interlayers may lead to the reduced band gap.•Tensile strain will lower the force constants and soften the optical modes, moreover, some new vibration modes will be induced.•The frequency shift is sensitive to the loading modes, uniaxial or biaxial.

First-principle calculations are done to study the electronic states and lattice vibration of monolayer MoS2 under tensile strain. It is found that the band gap decreases with the strain, which is consistent with the experimental results measured by photoluminescence and adsorption spectra. The decreased band gap can be ascribed to the strain-sensitive ππ bond-like interaction between interlayers. As a result of lowered crystal symmetry, the degenerate E′ mode is split into two modes and some new modes are induced. The frequency shift of the E′ modes is different for the case under uniaxial and biaxial tensile strain. Hence, the electronic and optical properties of MoS2 should change with strain significantly. Accordingly, the performances of MoS2 based electronic/photoelectric devices can be optimized; and even new sensors might be designed to detect pressure.

Graphical abstractUnder tensile strain, the electronic states and the lattice vibration of monolayer MoS2 change considerably, resulting in the reduced band gap and softened vibration modes. This is closely related to the strain-sensitive ππ bond-like interaction between inter-layers.Figure optionsDownload full-size imageDownload as PowerPoint slide