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Description:

Transition metal dichalcogenide monolayers represent unique platforms for studying both electronic and phononic interactions as well as intra- and intervalley exciton com- plexes. Here, we investigate the upconversion of exciton photoluminescence in MoSe2 monolayers. Within the nominal transparency window of MoSe2 the exciton emission is enhanced for resonantly addressing the spin-singlet negative trion and neutral biexci- ton at a few tens of meV below the neutral exciton transition. We identify that the A’1 optical phonon at the K valley provides the energy gain in the upconversion process at the trion resonance, while ZA(K) phonons with their spin- and valley-switching property support the biexciton driven upconversion of the exciton emission. Interestingly, the latter is unpolarized due to a superposition state formed by the two bright excitons at the K valleys. Our study highlights high-order exciton complexes interacting with optical and acoustic K-valley phonons and upconverting light into the bright exciton.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Van der Waals contacts, Schottky barrier, MoS2 transistor

Date published: 2023-10-05

Publisher: American Chemical Society (ACS)

Journal:

• The Journal of Physical Chemistry Letters (ISSN: 19487185) vol. 14 issue. 39 p. 8702-8708

Funding:

• Deutsche Forschungsgemeinschaft TRR 160 B4 249492093
• European Commission 101017733
• National Center for Research and Development QUANTERAII/1/74/EQUAISE/2022

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1021/acs.jpclett.3c01982

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Updated at: 2025-02-14 16:30:18 +0900

Published on MDR: 2025-02-14 16:30:18 +0900