Triplet–triplet annihilation upconversion kinetics of C60–Bodipy dyads as organic triplet photosensitizers

Abstract

Three new triplet photosensitizers consisting of a bodipy derivative and C₆₀ moieties were synthesized for triplet–triplet annihilation upconversion of perylene. With the extension of the π-conjugated structure of the bodipy derivative, the three photosensitizers exhibited different absorption wavelengths, e.g. 517 nm for B-2, 532 nm for B-4, and 557 nm for B-6. The steady-state and transient absorption, steady-state fluorescence, and upconverted fluorescence emission were investigated to reveal step-by-step the dynamic processes of the above systems. The quantum yields of intramolecular energy transfer, intersystem crossing, and triplet–triplet energy transfer were measured. From the upconverted fluorescence emission spectra, the overall quantum yield of the triplet–triplet annihilation upconversion, Φ_UC, was determined to be 5.80% for B-2, 7.95% for B-4, and 4.99% for B-6.