  Recent advances in emerging atomically thin transition metal dichalcogenide
semiconductors with strong light-matter interactions and tunable optical
properties provide novel approaches for realizing new material functionalities.
Coupling two-dimensional semiconductors with all-dielectric resonant
nanostructures represents an especially attractive opportunity for manipulating
optical properties in both the near-field and far-field regimes. Here, by
integrating single-layer WSe2 and titanium oxide (TiO2) dielectric metasurfaces
with toroidal resonances, we realized robust exciton emission enhancement over
one order of magnitude at both room and low temperatures. Furthermore, we could
control exciton dynamics and annihilation by using temperature to tailor the
spectral overlap of excitonic and toroidal resonances, allowing us to
selectively enhance the Purcell effect. Our results provide rich physical
insight into the strong light-matter interactions in single-layer TMDs coupled
with toroidal dielectric metasurfaces, with important implications for
optoelectronics and photonics applications.
