Assembly of Centimeter-Scale Plasmonic Nanocavities for Bright and Ultrafast Emission of Red Carbon Dots

Carbon dots (CDs) have great potentials in quantum emitters due to their simple synthesis, low cost, high stability, and tunable band gap; however, the low solid-state emission efficiency, as well as nanosecond-scale radiative lifetime, limits their applications requiring bright and fast emission. Here, a bright and ultrafast emission of red-emissive carbon dots (R-CDs) with narrow bandwidth (<30 nm) is achieved at room temperature by coupling with a plasmonic nanopatch antenna (NPA). The NPA manufacturing combines a conventional spin-coating process with a conformal transfer-print thin film technology, providing a widely applicable nanocavity for field enhancement with uniform quality in centimeter scale and accurate control of the position of emitters. The effective NPA–CD coupling generates an increase in the emission intensity of a factor of 76 and a shortened radiative lifetime of 80 ps, which demonstrates an 82-fold faster rate than the emission rate of uncoupled R-CDs. The NPA structure also shows striking enhancement of Raman spectra of carbon dots with an enhancement factor over 105. These results may benefit the low-cost and large-scale fabrication of plasmonic cavity and enable carbon dots to find applications in quantum optics, from low-threshold nanolaser to single-photon source.