Cyan-to-yellow color tunable NaAlSiO4:Eu2+ with high quantum efficiency and thermal stability for white light-emitting diodes

Phosphor-converted white light-emitting diodes (white pc-LEDs) require efficient and thermal stable phosphors with broad-band emission to fulfill the requirement of high-quality illumination. In this work, Eu2+-activated nepheline, NaAlSiO4:Eu2+ with tunable emission was synthesized successfully. The emission band can be tuned from cyan to yellow region through changing flux, synthetic temperature, and/or Eu2+ doping content without changing crystal structure. The tunable emission is due to the variation of occupancy of Eu2+ on two different Na crystallographic sites. Results indicate that using H3BO3 as flux, increasing synthetic temperature and Eu2+ content are beneficial to efficient yellow emission of NaAlSiO4:Eu2+. Na0.92AlSiO4:0.04Eu(2+) synthesized at 1300 degrees C with H3BO3 has high internal (95.14%) and external (78.14%) quantum efficiencies. It also exhibits excellent thermal stability that the emission intensity keeps nearly unchanged within 100 degrees C. The fabricated proto type white pc-LED by using the phosphor as a yellow component has a color rendering index of 92.0. These results indicate that the as-synthesized phosphors have great potential for application in white pc-LED devices.

Automated summary

Eu2+-activated nepheline, NaAlSiO4:Eu2+, with tunable emission from cyan to yellow region, was successfully synthesized in this study. The emission band can be adjusted by changing synthetic conditions without affecting crystal structure. Results show that using H3BO3 as flux, increasing synthetic temperature and Eu2+ content favor efficient yellow emission. The as-synthesized phosphors exhibit high quantum efficiencies and excellent thermal stability, making them suitable for white pc-LED applications.