Uniaxial tensile strain modulation of the photoinduced ultrafast charge transfer dynamics in the MoS2/WS2 heterostructure

Strain engineering has been reported as an effective strategy for controlling the electronic properties and modulating the charge transfer dynamics in two-dimensional (2D) semiconducting materials. Herein, by performing the time-dependent ab initio nonadiabatic molecular dynamics simulation, we deeply investigated the uniaxial tensile strain-modulated photoinduced ultrafast charge transfer dynamics of MoS2/WS2 heterostructure. Our calculations demonstrate that the uniaxial tensile strain along the armchair/zigzag direction can significantly modulate the ultrafast electron transfer dynamics in the MoS2/WS2 heterostructure, but has little effect on the hole transfer dynamics. Most importantly, the photoexcited electron transfer process of the system under 4% zigzag direction tensile strain is completely suppressed, and the photoexcited hole transfer pathway is turned into MoS2@Γ → WS2@Γ. It is further revealed that the time scale of ultrafast electron transfer of MoS2/WS2 heterostructure subjected to 2% zigzag direction tensile strain is about 1.7 ps with the transfer pathway of WS2@K → MoS2@K, and the time scale of ultrafast hole transfer is 32 fs. Overall, these findings strongly support that the tunability of photoinduced ultrafast charge transfer dynamics by strain engineering implies potential applications in the flexible electronics and optoelectronics based on 2D materials. Graphic abstract