三重項-三重項消滅に基づくフオトン?アップコンバージョンとその新展開

摘要

Photon upconversion based on triplet-triplet annihilation (TTA-UC) has recently attracted much attention because it works with weak non-coherent light such as sunlight. It has a great potential in many applications from solar energy harvesting to bioimaging and photodynamic therapy. By changing the combination of donor (triplet sensitizer) and acceptor (emitter), it is possible to achieve different wavelength conversions such as near IR (NIR)-to-visible and visible-to-UV UC. Most previous TTA-UC systems have used molecular diffusion in solution or soft polymer, however, they require strong excitation light and suffer from severe oxygen quenching. Instead of this molecular-diffusion-based mechanism, we have been proposing a new energy-migration-based mechanism, where excited triplet energy migrates among dense chromophore assemblies and annihilate to show UC emission. This new strategy allows highly efficient, air-stable UC emission at extremely low excitation intensity, opening a new era of UC research towards real-world applications.