Abstract
The success of van der Waals heterostructures made of graphene, metal dichalcogenides and other layered materials, hinges on the understanding of charge transfer across the interface as the foundation for new device concepts and applications. In contrast to conventional heterostructures, where a strong interfacial coupling is essential to charge transfer, recent experimental findings indicate that van der Waals heterostructues can exhibit ultrafast charge transfer despite the weak binding of these heterostructures. Here we find, using time-dependent density functional theory molecular dynamics, that the collective motion of excitons at the interface leads to plasma oscillations associated with optical excitation. By constructing a simple model of the van der Waals heterostructure, we show that there exists an unexpected criticality of the oscillations, yielding rapid charge transfer across the interface. Application to the MoS 2 /WS 2 heterostructure yields good agreement with experiments, indicating near complete charge transfer within a timescale of 100 fs.
Original language | English |
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Article number | 11504 |
Journal | Nature Communications |
Volume | 7 |
DOIs | |
State | Published - May 10 2016 |
Funding
We thank D. Han, E. Cruz-Silva and M. Lucking for helps on TDDFT-MD and valuable suggestions. We also thank Ashok Kumar for sharing with us the pseudopotentials and Liang Chen for helping with understanding related experiments. H.W., D.W., Y.S. and S.Z. were supported by the US Department of Energy (DOE) under Grant No. DESC0002623, J.B. was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF-2015R1C1A1A02037024) and KBSI grant C36117, L.L. was supported by Eugene P. Wigner Fellowship at the Oak Ridge National Laboratory and the Center for Nanophase Materials Sciences (a DOE Office of Science User Facility), and V.M. acknowledges support from the Office of Naval Research and New York State under NYSTAR program C080117. We also acknowledge the supports by the supercomputer time provided by NERSC under the Grant No. DE-AC02-05CH11231 and the Center of Computational Innovations (CCI) at RPI.