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Title: Efficient Interlayer Relaxation and Transition of Excitons in Epitaxial and Non-epitaxial MoS2/WS2 Heterostructures

Semiconductor heterostructurs provide a powerful platform for the engineering of excitons. Here we report on the excitonic properties of two-dimensional (2D) heterostructures that consist of monolayer MoS2 and WS2 stacked epitaxially or non-epitaxially in the vertical direction. We find similarly efficient interlayer relaxation and transition of excitons in both the epitaxial and non-epitaxial heterostructures. This is manifested by a two orders of magnitude decrease in the photoluminescence and an extra absorption peak at low energy region of both heterostructures. The MoS2/WS2 heterostructures show weak interlayer coupling and essentially act as an atomic-scale heterojunction with the intrinsic band structures of the two monolayers largely preserved. They are particularly promising for the applications that request efficient dissociation of excitons and strong light absorption, including photovoltaics, solar fuels, photodetectors, and optical modulators. Our results also indicate that 2D heterostructures promise to provide capabilities to engineer excitons from the atomic level without concerns of interfacial imperfection.
 [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [3] ;  [3] ;  [1] ;  [2] ;  [4]
  1. North Carolina State Univ., Raleigh, NC (United States)
  2. Univ. of North Carolina, Charlotte Hill, NC (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. North Carolina State University
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 15; Journal ID: ISSN 1530-6984
American Chemical Society
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
36 MATERIALS SCIENCE; Molybdenum disulfide; tungsten disulfide; van der Waals epitaxy; interlayer charge transfer; two-dimensional heterojunction