Regensburg 2022 – scientific programme
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DS: Fachverband Dünne Schichten
DS 12: 2D Materials 4 (joint session HL/CPP/DS)
DS 12.7: Talk
Tuesday, September 6, 2022, 11:30–11:45, H36
Brightening of a dark monolayer semiconductor via strong light-matter coupling in a cavity — •Hangyong Shan1, Ivan Iorsh2, Bo Han1, Falk Eilenberger4, Martin Esmann1, Sebastian Klembt3, Sven Höfling3, Carlos Antón-Solanas1, Ivan A. Shelykh2, and Christian Schneider1 — 1Oldenburg University, Oldenburg, Germany. — 2St. Petersburg, Russia — 3Universität Würzburg, Würzburg, Germany — 4Friedrich Schiller University, Jena, Germany
We study the modification of the material properties via strong coupling and demonstrate an effective inversion of the excitonic band-ordering in a monolayer of WSe2 with spin-forbidden, optically dark ground state. 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, which results in the brightening of this intrinsically dark material. We probe this effective 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.