Blue-light excitable red-emitting Eu3+-doped TiO2 phosphor for WLED applications: Judd-Ofelt analysis and systematic investigation on its optical properties

Red-emitting Eu3+-activated TiO2 phosphors with excellent color purity of 99.9% have been successfully synthesized by a facile sol-gel method. PLE spectrum demonstrates that the obtained products have absorption bands ranging from 370 to 540 nm, with the highest band peaking at 464 nm. Under the blue excitation of 464 nm, the characteristic emissions of Eu3+ ions corresponding to the D-5(0) -> F-7(J) transitions are observed, with the dominant emission peak at 614 nm. The optimal annealing temperature and dopant concentration are 5 h at 500 ? and 1.3 mol%, respectively. The PL quenching mechanism is attributed to the dipole-quadrupole interaction. The Judd-Ofelt analysis is carried out to explore the local structure environment around the Eu3+ ions. It is found that the highest asymmetry of the local environment surrounding Eu3+ ions and the strongest covalence Eu-O bond is attained at the annealing temperature of 500 ? and the activation energy is determined to be 0.385 eV. The fluorescence lifetime of the 614 nm emission was found to be 0.44 ms. These results indicate that the Eu3+-doped TiO2 phosphor may be a promising red-emitting phosphor for white light-emitting diodes.

Automated summary

Red-emitting Eu3+-activated TiO2 phosphors with excellent color purity have been synthesized. Under blue excitation, characteristic emissions of Eu3+ ions at 614 nm are observed, indicating potential applications in white light-emitting diodes.