Bodipy-Anthracene Dyads as Triplet Photosensitizers: Effect of Chromophore Orientation on Triplet-State Formation Efficiency and Application in Triplet-Triplet Annihilation Upconversion

Bodipy-anthracene dyads with two chromophores assuming orthogonal geometry to enhance the spin-orbital charge-transfer intersystem crossing (SOCT-ISC) were prepared. The photosensitizers show strong absorption of visible light, efficient triplet-state formation (quantum yield 90%), and a long-lived triplet state (85 mu s). The dipole moment orientation exerts significant effect on the ISC efficiency. It is also the first time that photosensitizers based on SOCT-ISC were used for triplet-triplet annihilation upconversion. The upconversion quantum yield is up to 15.8%.