Highly thermally stable and tunable luminescence in microwave-assisted synthesized Na3Ca4(TeO3)(PO4)3:Dy3+,Eu3+ for ultra-high color rendering white light-emitting diodes

Abstract

For the commercial application of the Eu3+-activated red phosphors in NUV (∼365 nm)-excited phosphor-converted white light-emitting diodes (pc-wLED), the serious obstacle is that they cannot be efficiently excited by ∼365 nm. To deal with the trouble, we employed the energy transfer between Dy3+ sensitizer excited by ∼365 nm and Eu3+ activator, and a color-tunable phosphor Na3Ca4(TeO3)(PO4)3 (NCTP):Dy3+,Eu3+ was prepared via a fast microwave-assisted solid-state reaction. Under the 363 nm excitation, the luminous color is adjusted to red owing to the Dy3+→Eu3+ energy transfer with high efficiency, which is controlled by the dipole–dipole interaction. Moreover, the introduction of Dy3+ sensitizers in NCTP:Eu3+ enhances the structural rigidity, resulting in high luminescence thermostability. The luminescent intensity at 423 K remains 90.7% of that at 298 K. Notably, the 365 nm chip-excited pc-wLED device assembled with NCTP:0.09Dy3+,0.4Eu3+, commercial blue BaMgAl10O17:Eu2+, and green (Ba,Sr)2SiO4:Eu2+ phosphors emits warm-white light (0.3657,0.3725) with the ultra-high Ra (94.9) and low CCT (4399 K). This work offers a feasible Dy3+→Eu3+ energy transfer path for the development of efficient Eu3+-activated red phosphor towards ultra-high color rendering pc-wLED.