Tensile Strain-Controlled Photogenerated Carrier Dynamics at the van der Waals Heterostructure Interface.

ABSTRACT

Customizing the photogenerated carrier dynamics would make the two-dimensional (2D) materials highly adaptable to various application scenarios. On the basis of time-domain ab initio nonadiabatic molecular dynamics simulation, we find that 4% tensile strain can suppress the electron transfer at the van der Waals heterostructure MoS2/WS2 interface. Our analysis shows that after the electron-hole pair is excited in the K valley in WS2 direct electron transfer from WS2@K to MoS2@K is very difficult because of the weak interlayer coupling in the K valley, and thus, it happens through the T valley as WS2@K-MoS2@T-MoS2@K. When the tensile strain is applied, the energy of WS2@K is decreased, resulting in the suppression of electron transfer. Our study suggests that tuning of the interlayer charge-transfer dynamics by external strain is possible, which provides valuable insights into the functional design of photonic devices based on 2D materials.