Chiral self-assembly regulated photon upconversion based on triplet-triplet annihilation

Photon upconversion (UC) based on triplet-triplet annihilation (TTA) in quasi-solid or solid state has been attracting much research interest due to its great potential applications. To get effective UC, precisely controlled donor-acceptor interaction is vitally important. Chiral self-assembly provides a powerful approach for sophisticated regulation of molecular interaction. Here we report a chiral self-assembly controlled TTA-UC system composed of chiral acceptor and achiral donor. It is found that racemic mixture of acceptors could form straight fibrous nanostructures, which show strong UC emission, while chiral assemblies for homochiral acceptors emit weak upconverted light. The racemic assemblies allow efficient triplet-triplet energy transfer (TTET) and further realize efficient UC emission, while the homochiral assemblies from chiral acceptor produce twisted nanostructures, suppressing efficient triplet energy transfer and annihilation. The establishment of such chiral self-assembly controlled UC system highlights the potential applications of triplet fusion in optoelectronic materials and provides a new perspective for designing highly effective UC systems.