Issue 29, 2019

Highly efficient and thermally stable single-activator white-emitting phosphor K2Ca(PO4)F:Eu2+ for white light-emitting diodes

Abstract

Phosphor-converted white light-emitting diodes (w-LEDs) have become the new generation of lighting. Several strategies have been introduced to realize a high CRI value for illumination. However, these strategies suffer from new problem(s), such as reabsorption, different deterioration rates among the phosphors, different thermal stability for diverse emission bands, and/or the decrease of quantum efficiency for the phosphor. Therefore, it is desired to develop new phosphors that not only realize a high CRI value for w-LEDs, but also resolve the above problems. In this work, a site-preference driven color-tunable Eu2+-activated K2Ca(PO4)F phosphor was prepared. The color-tunable phosphor exhibits two broad emission bands peaking at 485 and 660 nm upon UV excitation. White emission is realized in K2Ca(PO4)F:0.006Eu2+. The internal and external quantum efficiencies of the white-emitting phosphor are 91.5 and 66.9%, respectively. The phosphor also exhibits good thermal stability, namely, the emission intensity at 423 K maintains >80% of that at room temperature, and the intensity ratio between the two emission bands remains nearly unchanged within 423 K. A white LED device has also been fabricated using a 365 nm LED chip and K2Ca(PO4)F:0.006Eu2+, showing a high color rendering index (Ra = 87.6). These results indicate that the K2Ca(PO4)F:Eu2+ phosphor is a promising candidate for UV-pumped w-LEDs.

Graphical abstract: Highly efficient and thermally stable single-activator white-emitting phosphor K2Ca(PO4)F:Eu2+ for white light-emitting diodes

Supplementary files

Article information

Article type
Paper
Submitted
28 May 2019
Accepted
27 Jun 2019
First published
30 Jun 2019

J. Mater. Chem. C, 2019,7, 8982-8991

Highly efficient and thermally stable single-activator white-emitting phosphor K2Ca(PO4)F:Eu2+ for white light-emitting diodes

Y. Li, Z. Qiu, J. Zhang, X. Ji, X. Zhang, S. Liao, W. Zhou, L. Yu and S. Lian, J. Mater. Chem. C, 2019, 7, 8982 DOI: 10.1039/C9TC02844G

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