  We propose a novel scheme of photon upconversion based on harnessing the
energy of plasmonic hot carriers. Low-energy photons excite hot electrons and
hot holes in a plasmonic nanoparticle, which are then injected into an adjacent
semiconductor quantum well where they radiatively recombine to emit a photon of
higher energy. We theoretically study the proposed upconversion scheme using
Fermi-liquid theory and determine the upconversion quantum efficiency to be as
high as 25% in 5 nm silver nanocubes. This upconversion scheme is linear in its
operation, does not require coherent illumination, offers spectral tunability,
and is more efficient than conventional upconverters.
