Photon Upconversion Based on Sensitized Triplet-Triplet Annihilation ( s TTA) in Solids

The conversion of low-energy photons into radiation of higher energy is useful for bioimaging, 3D displays and other applications. In particular, upconversion of the infrared portion of the solar spectrum, which is typically not absorbed by the light-harvesting materials used in solar technologies, allows additional photons to be harnessed and boosts the efficiency of photovoltaic and photocatalytic devices. Therefore, low power photon upconversion of non-coherent light based on sensitized triplet-triplet annihilation (sTTA) has been recently recognized as a potential viable approach towards enhancing the efficiency of sunlight-powered devices through sub-bandgap photon harvesting.