Synthesis, photoluminescence, and energy transfer mechanism of a reactive Eu(III)-complex used in white light-emitting diodes

A reactive Eu(III)-complex Eu(TTA)3 ( UA ) was synthesized with 2-thenoyltrifluoroacetone (TTA) as primary ligand and undecylenic acid (UA) as active ligand. The structure of the complex was characterized by elemental analysis, FT-IR spectra, and UV–vis absorption spectra. The results indicate that the Eu(III) ion is successfully coordinated with primary ligand TTA and active ligand UA. Fluorescence spectra suggest that the complex exhibits excellent red emission of Eu(III) ion with a peak at 611 nm being monitored at 365 nm of near ultraviolet. Meanwhile, the complex has also shown a long fluorescence lifetime of 1.4259 ms and a high quantum yield of 86.7%. The singlet and triplet energy levels for the ligands of rare earth complexes were calculated using Gaussian 03 program package. Intramolecular energy transfer diagram was established and an energy transfer process following Dexter electron exchange mechanism was demonstrated, which provides the experimental data and theoretical foundation for the development of high-performance luminescent materials. The result of TGA shows that the complex keeps stable at 156°C or below. All the results demonstrate that the reactive Eu(III)-complex can be used as the red-light material in white light-emitting diodes phosphor.