The effects of intercalated environmental gas molecules on carrier dynamics in WSe 2 /WS 2 heterostructures.

Effective tuning of carrier dynamics in two-dimensional (2D) materials is significant for multi-scene device applications. Using first-principles and ab initio nonadiabatic molecular dynamics calculations, the kinetics of O 2 , H 2 O, and N 2 intercalation into 2D WSe 2 /WS 2 van der Waals heterostructures and its effect on carrier dynamics have been comprehensively explored. It is found that the O 2 molecule prefers to dissociate into atomic O atoms spontaneously after intercalation of WSe 2 /WS 2 heterostructures, whereas H 2 O and N 2 molecules remain intact. O 2 intercalation significantly speeds up the electron separation process, while H 2 O intercalation largely speeds up the hole separation process. The lifetime of excited carriers can be prolonged by O 2 or H 2 O or N 2 intercalations. These intriguing phenomena can be attributed to the effect of interlayer coupling, and the underlying physical mechanism for tuning the carrier dynamics is fully discussed. Our results provide useful guidance for the experimental design of 2D heterostructures for optoelectronic applications in photocatalysts and solar energy cells.