Journal
ACS NANO
Volume 8, Issue 12, Pages 12717-12724Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nn505736z
Keywords
van der Waals heterostructure; transition metal dichalcogenides; molybdenum disulfide; molybdenum diselenide; 2D materials; transient absorption; exciton
Categories
Funding
- National Science Foundation of USA [DMR-0954486, IIA-1430493]
- Kansas NSF EPSCoR First Award [EPS-0903806]
- University of Kansas
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [0954486] Funding Source: National Science Foundation
- Office of Integrative Activities [1430519] Funding Source: National Science Foundation
- Office of Integrative Activities
- Office Of The Director [1430493] Funding Source: National Science Foundation
- Office Of The Director [1430519] Funding Source: National Science Foundation
Ask authors/readers for more resources
We observe subpicosecond charge separation and formation of indirect excitons a van der Waals heterostructure formed by molybdenum disulfide and molybdenum diselenide monolayers. The sample is fabricated by manually stacking monolayer MoS2 and MoSe2 flakes prepared by mechanical exfoliation. Photoluminescence measurements confirm the formation of an effective heterojunction. In the transient absorption measurements, an ultrafast laser pulse resonantly injects excitons in the MoSe2 layer of the heterostructure. Differential reflection of a probe pulse tuned to the MoS2 exciton resonance is immediately observed following the pump excitation. This proves ultrafast transfer of electrons from MoSe2 to MoS2 layers, despite the strong Coulomb attraction from the holes in the resonantly excited excitons. Conversely, when excitons are selectively injected in MoS2, holes transfer to MoSe2 on an ultrafast time scale, too, as observed by measuring the differential reflection of a probe tuned to the MoSe2 resonance. The ultrafast charge transfer process is followed by the formation of spatially indirect excitons with electrons and holes residing in different layers. The lifetime of these indirect excitons are found to be longer than that of the direct excitons in individual MoS2 and MoSe2 monolayers.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available