Photoinduced Anomalous Electron Transfer Dynamics at a Lateral MoS₂-Graphene Covalent Junction

Photoinduced charge separation significantly affects the optoelectronic performance of the lateral MoS₂-graphene junctions. Generally, an adiabatic mechanism governs electron transfer (ET) at a chemically binding interface. Counterintuitively, we demonstrate, using nonadiabatic (NA) molecular dynamics, that an NA mechanism dominates the ET from MoS₂ to graphene in the lateral MoS₂-graphene covalent junction. The anomalous ET mechanism arising from the built-in electric field formed at the interface that decreases the donor-acceptor interaction by driving electrons and holes moving to opposite directions. Driven by both graphene and MoS₂ vibrations, the photoexcited electrons on MoS₂ rapidly transfer into graphene by the NA mechanism within 200 fs, which is faster than electron-phonon energy relaxation and ensures that "hot" electrons can be successfully extracted before they cool and lose energy to heat. The study establishes a mechanistic understanding of the complex charge-phonon dynamics in the lateral MoS₂-graphene junctions that are key to optoelectronic and photovoltaic applications.