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Issue 9, 2015
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K2Ln(PO4)(WO4):Tb3+,Eu3+ (Ln = Y, Gd and Lu) phosphors: highly efficient pure red and tuneable emission for white light-emitting diodes

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Abstract

A novel phosphate/tungstate family, K2Ln(PO4)(WO4) (Ln = Y, Gd and Lu) doped with Tb3+ and Eu3+ is synthesized via a conventional high-temperature solid-state reaction to explore new pure red phosphors with high critical concentration for white light-emitting diodes (WLEDs). The results from the Rietveld method show that the crystal structures of the hosts are composed of phosphate layers and tungstate zigzags, and the Ln3+–Ln3+-units are isolated by the [PO4]3− groups in phosphate layers. The critical concentration of Tb3+ and Eu3+ is up to 40–50% in the singly doped phosphors, which is ascribed to the interaction of the isolated Ln3+ ions being mitigated by [PO4]3− and [WO4]2− groups, such that the special structure of K2Ln(PO4)(WO4) helps the interaction of luminescence centres. The energy transfer from Tb3+ to Eu3+ in K2Ln(PO4)(WO4) is demonstrated by fluorescence decay times. By adjusting the ratio of Eu3+ and Tb3+, we can tune the emission colour of K2Ln(PO4)(WO4):Tb3+,Eu3+ from green to yellow, orange and pure red. For K2Tb0.5Eu0.5(PO4)(WO4), the internal quantum efficiency is as high as 76.45% under an excitation of 394 nm, and the emission intensity at 150 °C is 92.2% of that at 25 °C.

Graphical abstract: K2Ln(PO4)(WO4):Tb3+,Eu3+ (Ln = Y, Gd and Lu) phosphors: highly efficient pure red and tuneable emission for white light-emitting diodes

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Publication details

The article was received on 22 Oct 2014, accepted on 10 Dec 2014 and first published on 10 Dec 2014


Article type: Paper
DOI: 10.1039/C4TC02406K
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J. Mater. Chem. C, 2015,3, 2107-2114

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    K2Ln(PO4)(WO4):Tb3+,Eu3+ (Ln = Y, Gd and Lu) phosphors: highly efficient pure red and tuneable emission for white light-emitting diodes

    D. Wen, J. Feng, J. Li, J. Shi, M. Wu and Q. Su, J. Mater. Chem. C, 2015, 3, 2107
    DOI: 10.1039/C4TC02406K

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