Plasmon-Enhanced Two-Photon Absorption in Photoluminescent Semiconductor Nanocrystals

In this work, we demonstrate the two-photon fluorescence of covellite-phase copper sulfide nanodisks and investigate the role of the surface plasmon resonance on emission. Using selenium doping, we blue-shift the plasmon resonance toward the two-photon absorption edge. We observed a 3-fold enhancement of emission in these samples and report two-photon action cross sections that are an order of magnitude greater than conventional fluorophores. These nanomaterials offer a novel all-in-one platform for engineering plasmon exciton coupling in the absence of a physical or chemical interface.