Hot carriers in plasmonic systems for photon upconversion
Photons absorbed by small metal nanoparticles create hot carriers in the metal nanoparticle which decay too quickly to be useful. My research proposes trapping these hot-carriers to slow down their decay process and thereby increasing the chance of harnessing their energy. Such a scheme may be implemented using a metal/semiconductor quantum well heterostructure. It is possible to arrange this system such that it absorbs low-energy photons, creates hot-carriers which are trapped in the quantum well and the quantum well emits high-energy photons. Thus photon upconversion, a new functionality is possible by harnessing the energy of lost photons.
This novel scheme of photon upconversion based on harnessing the energy of plasmonic hot carriers is promising because the theoretical prediction of the upconversion quantum efficiency is as high as 25% in 5 nm silver nanocubes. Current solid-state upconverters are only 2-5% efficient. Additionally, this upconversion scheme is linear in its operation, does not require coherent illumination, and offers spectral tunability.