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arXiv · 2304.05957

Radiative suppression of exciton-exciton annihilation in a two-dimensional semiconductor

Luca Sortino·Merve Gülmüs·Benjamin Tilmann·Leonardo de S. Menezes·Stefan A. Maier
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Abstract

Two-dimensional (2D) semiconductors possess strongly bound excitons, opening novel opportunities for engineering light-matter interaction at the nanoscale. However, their in-plane confinement leads to large non-radiative exciton-exciton annihilation (EEA) processes, setting a fundamental limit for their photonic applications. In this work, we demonstrate suppression of EEA via enhancement of light-matter interaction in hybrid 2D semiconductor-dielectric nanophotonic platforms, by coupling excitons in WS$ _2 $ monolayers with optical Mie resonances in dielectric nanoantennas. The hybrid system reaches an intermediate light-matter coupling regime, with photoluminescence enhancement factors up to 10$ ^2 $. Probing the exciton ultrafast dynamics reveal suppressed EEA for coupled excitons, even under high exciton densities $>$ 10$^{12}$ cm$^{-2} $. We extract EEA coefficients in the order of 10$^{-3} $, compared to 10$^{-2} $ for uncoupled monolayers, as well as absorption enhancement of 3.9 and a Purcell factor of 4.5. Our results highlight engineering the photonic environment as a route to achieve higher quantum efficiencies for low-power hybrid devices, and larger exciton densities, towards strongly correlated excitonic phases in 2D semiconductors.

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Luca Sortino, Merve Gülmüs, Benjamin Tilmann, Leonardo de S. Menezes, Stefan A. Maier. 2023-04-12. Radiative suppression of exciton-exciton annihilation in a two-dimensional semiconductor. https://arxiv.org/abs/2304.05957

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