Greatly amplified spontaneous emission of colloidal quantum dots mediated by a dielectric‐plasmonic hybrid nanoantenna

Optical nanoantennas can efficiently harvest electromagnetic energy from nanoscale space and boost the local radiation to the far field. The dielectric‐metal nanogap is a novel design that can help to overcome the core issue of optical loss in all‐metal nanostructures while enabling photon density of states larger than that in all‐dielectric counterparts. This article reports that a crystalline spherical silicon nanoparticle on metal film (SiNPoM) nanoantenna can largely enhance the spontaneous emission intensity of quantum dots by an area‐normalized factor of 69 and the decay rate by 42‐fold compared with quantum dots on glass. A high total quantum efficiency of over 80%, including ~20% for far‐field radiation and ~60% for surface plasmon polaritons, is obtained in simulation. Thanks to not only the low optical loss in dielectric nanoparticles but also the appropriate gap thickness which weakens the non‐radiative decay due to the quenching from metal. Mie resonant modes additionally provide the flexible control of far‐field emission patterns. Such a simple optical nanoantenna can be combined with various nanoscale optical emitters and easily extended to form large area metasurfaces functioning as active regions in light‐emitting devices in applications such as advanced display, wireless optical communication, and quantum technology.