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Engineering the properties of quantum materials via strong light-matter coupling is a compelling research direction with a multiplicity of modern applications. Those range from modifying charge transport in organic molecules in the strong coupling regime, steering particle correlation and interactions, and even controlling chemical reactions. Here, we study the modification of the material properties via strong coupling and demon- strate an effective inversion of the excitonic band-ordering in a monolayer of WSe2 with spin-forbidden, optically dark ground state, which results in the brightening of this intrinsically dark material. In our experiments, we harness the strong light-matter coupling between cavity photon and the high energy, spin-allowed bright exciton, and thus creating two bright polaritonic modes in the optical bandgap with the lower polariton mode pushed below the WSe2 dark state. We demonstrate that in this regime the commonly observed luminescence quenching stemming from the fast relaxation to the dark ground state is prevented. We probe this effec- tive brightening by temperature-dependent photoluminescence, and we find an excellent agreement with a theoretical model accounting for the inversion of the band ordering and phonon-assisted polariton relaxation.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: Quantum materials, light-matter coupling, excitonic band-ordering

Date published: 2022-05-30

Publisher: Springer Science and Business Media LLC

Journal:

• Nature Communications (ISSN: 20411723) vol. 13 issue. 1 3001

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

MDR DOI:

First published URL: https://doi.org/10.1038/s41467-022-30645-5

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Updated at: 2025-02-28 08:30:17 +0900

Published on MDR: 2025-02-28 08:30:18 +0900