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Nat Nanotechnol. 2014 Sep;9(9):682-6. doi: 10.1038/nnano.2014.167. Epub 2014 Aug 24.

Ultrafast charge transfer in atomically thin MoS₂/WS₂ heterostructures.

Author information

1
1] Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA [2].
2
1] Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA [2] Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [3].
3
Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China.
4
Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
5
1] Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Materials Science and Engineering, University of California, Berkeley, California 94720-1760, USA [3] School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, USA.
6
1] Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Materials Science and Engineering, University of California, Berkeley, California 94720-1760, USA.
7
1] Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA [2] Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [3] Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

Abstract

Van der Waals heterostructures have recently emerged as a new class of materials, where quantum coupling between stacked atomically thin two-dimensional layers, including graphene, hexagonal-boron nitride and transition-metal dichalcogenides (MX2), give rise to fascinating new phenomena. MX2 heterostructures are particularly exciting for novel optoelectronic and photovoltaic applications, because two-dimensional MX2 monolayers can have an optical bandgap in the near-infrared to visible spectral range and exhibit extremely strong light-matter interactions. Theory predicts that many stacked MX2 heterostructures form type II semiconductor heterojunctions that facilitate efficient electron-hole separation for light detection and harvesting. Here, we report the first experimental observation of ultrafast charge transfer in photoexcited MoS2/WS2 heterostructures using both photoluminescence mapping and femtosecond pump-probe spectroscopy. We show that hole transfer from the MoS2 layer to the WS2 layer takes place within 50 fs after optical excitation, a remarkable rate for van der Waals coupled two-dimensional layers. Such ultrafast charge transfer in van der Waals heterostructures can enable novel two-dimensional devices for optoelectronics and light harvesting.

PMID:
25150718
DOI:
10.1038/nnano.2014.167

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