Thermally-assisted photosensitized emission in a trivalent terbium complex

Luminescent lanthanide complexes containing effective photosensitizers are promising materials for use in displays and sensors. The photosensitizer design strategy has been studied for developing the lanthanide-based luminophores. Herein, we demonstrate a photosensitizer design using dinuclear luminescent lanthanide complex, which exhibits thermally-assisted photosensitized emission. The lanthanide complex comprised Tb(III) ions, six tetramethylheptanedionates, and phosphine oxide bridge containing a phenanthrene frameworks. The phenanthrene ligand and Tb(III) ions are the energy donor (photosensitizer) and acceptor (emission center) parts, respectively. The energy-donating level of the ligand (lowest excited triplet (T-1) level = 19,850 cm(-1)) is lower than the emitting level of the Tb(III) ion (D-5(4) level = 20,500 cm(-1)). The long-lived T-1 state of the energy-donating ligands promoted an efficient thermally-assisted photosensitized emission of the Tb(III) acceptor (D-5(4) level), resulting in a pure-green colored emission with a high photosensitized emission quantum yield (73%). Luminescent lanthanide complexes are promising materials for use in displays and sensors, however, these materials often undergo thermal quenching. Here, the authors synthesize and characterize a terbium dinuclear phosphine oxide-bridged phenanthrene complex, which exhibits thermally-enhanced emission.

Automated summary

In this study, a photosensitizer design strategy using a dinuclear luminescent lanthanide complex was demonstrated, which exhibited thermally-assisted photosensitized emission. The complex consisted of Tb(III) ions, six tetramethylheptanedionates, and a phosphine oxide bridge containing a phenanthrene frameworks. The phenanthrene ligand and Tb(III) ions acted as the energy donor and acceptor parts, respectively. The efficient thermally-assisted photosensitized emission of the Tb(III) acceptor resulted in a pure-green colored emission with a high photosensitized emission quantum yield of 73%.