New Eu2+-activated borophosphate phosphors Ba3(ZnB5O10)PO4 for near-ultraviolet-pumped white light-emitting diodes

Abstract

We presented a series of Ba3(ZnB5O10)PO4: Eu2+ borophosphate phosphors and highlighted their photoluminescence characteristics of intrinsic Eu2+ emission. Under near-ultraviolet excitation, the composition-optimized Ba2.95(ZnB5O10)PO4: 0.05Eu2+ generated bright blue emission peaking at 415 nm with an internal quantum efficiency of 30.1%, corresponding to the electric-dipole allowed 4f-5d transition of the Eu2+ ions. The nonradiative transition between Eu2+ ions in Ba3(ZnB5O10)PO4: Eu2+ phosphors was attributable to be the dipole–dipole interaction, and the activation energy for thermal quenching was calculated to be 0.223 eV. Crystallographic site-occupations of Eu2+ ions in the Ba3(ZnB5O10)PO4 host were also assigned and only one Eu2+ luminescence center that substituted nine-coordinated Ba site was confirmed. The Ba2.95(ZnB5O10)PO4: 0.05Eu2+ phosphor exhibited a better light yield with chromaticity coordinates of (0.168, 0.049) and correlated color temperature of 2009 K than that of commercial phosphor BaMgAl10O17: Eu2+. These results indicate the Ba3(ZnB5O10)PO4: Eu2+ phosphors are competitive as the promising blue-emitting phosphor-converted materials for white light-emitting diodes.