Observation of Hole Transfer in MoS2/WS2 Van der Waals Heterostructures

The ultrafast dynamics for the formation/recombination of interlayer exciton and charge transfer in MoS2/WS2 heterostructures are studied by pump–probe measurements combined with density functional theory simulations. MoS2/WS2 heterostructure forms a type-II band alignment where the conduction band minimum is in MoS2 and the valance band maximum locates in the WS2 layer, respectively. By modulating the transient absorption configurations, a significant hole transferring process is observed from the MoS2 layer to the WS2 layer, instead of electrons moving oppositely, forming spatially interlayer excitons with longer lifetimes than that occurring in individual monolayers in hundreds of femtoseconds. This work gives a comprehensive understanding of ultrafast exciton dynamics of MoS2/WS2 and confirms its potential for realizable gate-controllable optoelectronics.