Interlayer Coherent Dipole–Dipole Coupling Facilitates Charge Transfer in Multilayer Transition Metal Dichalcogenide Heterostructures

Abstract

Inserting intermediate layers in transition metal dichalcogenide heterostructures (TMD HSs) has become an efficient approach to modulating interlayer charge transfer rates. However, it could not only modify the distance of charge transfer but also potentially alter the interlayer coupling strength within HSs, which would profoundly influence the charge transfer rate in the opposite direction. Here, to gain insight into the dual roles of inserted intermediate layers in multilayer TMD HSs, MoS₂-nL WSe₂-MoSe₂ (n = 1–3) HSs were designed and systemically investigated. Different from the electron tunneling model following exponential behavior, we demonstrate that the coherent dipole–dipole coupling between 2L WSe₂ and MoSe₂ occurs, facilitating the averaged electron transfer rate (1/0.21 ps^–1) from MoSe₂ to MoS₂. This is 3.7 times (an order of magnitude) faster than that of 1/0.77 ps^–1 (1/2.08 ps^–1) in the MoS₂-1L WSe₂-MoSe₂ HS (MoS₂-3L WSe₂-MoSe₂ HS), emphasizing its importance in multilayer TMD HS device design.