Momentum-resolved Interlayer Charge and Energy Transfer in a Monolayer WSe2/Graphene Heterostructure
- PC Online Talk
- Date: Oct 29, 2020
- Time: 11:00 AM (Local Time Germany)
- Speaker: Dr. Shuo Dong
- FHI Department PC

Upon photoexcitation below the ML-WSe2 bandgap, the conduction band
minima (K and Q valleys) of ML-WSe2 are found to be populated with a 50
fs time delay with respect to the excited states of graphene,
unambiguously revealing interlayer charge transfer (ICT) through hot
electron injection. By tuning the pump wavelength near resonance with
the ML-WSe2 A-exciton, we observe a balanced charge flow of electrons
and holes, evidencing an efficient energy transfer from the excitons in
ML-WSe2 to the graphene layer as quasiparticles. Thereby, the finite
center-of-mass momentum of excitons in semiconducting WSe2 compensates
the momentum mismatch of quasi-free carriers in the linearly dispersing
graphene bands, preserving the momentum-conserved interlayer energy
transfer (IET).
[1] Jin, C. et al. Ultrafast dynamics in van der waals heterostructures. Nature nanotechnology 13,994–1003 (2018).
[2] Froehlicher, G., Lorchat, E. & Berciaud, S. Charge versus energy
transfer in atomically thingraphene-transition metal dichalcogenide van
der Waals heterostructures. Physical Review X 8, 011007 (2018)
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