Sensitized triplet–triplet annihilation based photon upconversion in full organic and hybrid multicomponent systems

In the last 15 years, attention dedicated to organic conjugated systems experienced outstanding growth because of renewed interest in mechanisms involving triplet states such as singlet fission, thermally activated delayed fluorescence, and intersystem crossing enhanced phosphorescence. Photon upconversion via sensitized triplet–triplet annihilation ( sTTA) enables conversion low-energy photons into high-energy ones, it has been proposed multicomponent an efficient managing strategy non-coherent photons. This mechanism exploits two optically dark emitter moieties produce The annihilating triplets are through Dexter energy transfer by a light-harvester, typically molecule or nanocrystal, so sTTA is usually performed bi-component systems. high yield observed at low excitation intensities stimulated thriving research field, leading development large family fully hybrid upconverters. Here, we compare evolution these families with respect main figures merit, highlighting strengths weaknesses both approaches, according results reported literature. data presented also discussed perspective future developments pointing out challenges that still be faced for technological use process.