Active control of excitonic strong coupling and electroluminescence in electrically driven plasmonic nanocavities.

Zheng, Junsheng; Krasavin, Alexey V; Yang, Ruoxue; Wang, Zhenxin; Feng, Yuanjia; Tang, Longhua; Li, Linjun; Guo, Xin et al. · Sci Adv · 2025

basic_science · Level V

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Abstract

Enhancement and active control of light-matter interactions at the atomic scale is important for developing next-generation nanophotonic and quantum optical devices. Here, we demonstrate electric control of excitonic strong coupling and electroluminescence (EL) by integrating a semiconductor monolayer into a nanometer gap of single electrically driven nanocube-on-mirror plasmonic nanocavities, which provide unmatched optical and electrical confinement. In particular, in a strongly coupled system of nanocavity plasmons and tungsten diselenide (WSe<sub>2</sub>) excitons, an ultrastrong electric field generated in the nanocavity gap enables reversible modulation of the Rabi splitting between ~108 and 102 milli-electron volts with a bias of only 2.5 volts. In the quantum tunneling regime (realized by decreasing the gap size), by injection of carriers into a nanocavity-integrated tungsten disulfide (WS<sub>2</sub>) monolayer, spectrally tunable EL (controlled by the bias polarity) is achieved with a room-temperature quantum efficiency reaching ~3.5%, showing an improvement of more than 10<sup>3</sup> times over previous works.