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

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 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. Enhancing light-matter interaction in 2D semiconductors coupled to Mie-resonant dielectric nanoantennas leads to the suppression of exciton-exciton annihilation, overcoming a fundamental limit for light emission in atomically thin materials.