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Narrow-band red-emitting Sr[LiAl3N4]:Eu2+ as a next-generation LED-phosphor material

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Abstract

To facilitate the next generation of high-power white-light-emitting diodes (white LEDs), the discovery of more efficient red-emitting phosphor materials is essential. In this regard, the hardly explored compound class of nitridoaluminates affords a new material with superior luminescence properties. Doped with Eu2+, Sr[LiAl3N4] emerged as a new high-performance narrow-band red-emitting phosphor material, which can efficiently be excited by GaN-based blue LEDs. Owing to the highly efficient red emission at λmax ~ 650 nm with a full-width at half-maximum of ~1,180 cm−1 (~50 nm) that shows only very low thermal quenching (>95% relative to the quantum efficiency at 200 °C), a prototype phosphor-converted LED (pc-LED), employing Sr[LiAl3N4]:Eu2+ as the red-emitting component, already shows an increase of 14% in luminous efficacy compared with a commercially available high colour rendering index (CRI) LED, together with an excellent colour rendition (Ra8 = 91, R9 = 57). Therefore, we predict great potential for industrial applications in high-power white pc-LEDs.

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Figure 1: Photoluminescence properties of next-generation red-emitting Sr[LiAl3N4]:Eu2+.
Figure 2: Crystal structure characterization of next-generation red-emitting Sr[LiAl3N4]:Eu2+.
Figure 3: Structural overview of next-generation red-emitting Sr[LiAl3N4]:Eu2+.
Figure 4: Morphology and composition of next-generation red-emitting Sr[LiAl3N4]:Eu2+.
Figure 5: Low-temperature luminescence of next-generation red-emitting Sr[LiAl3N4]:Eu2+.

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Acknowledgements

The authors thank T. Miller and C. Hoch for recording the single-crystal X-ray data and C. Minke for performing the EDX and solid-state NMR measurements (all at LMU Munich). We would like to thank P. Huppertz and H. Ohland, Philips Technologie GmbH Lumileds Development Center Aachen for luminescence measurements. Furthermore the authors gratefully acknowledge financial support from the Fonds der Chemischen Industrie (FCI).

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P.P., P.J.S. and W.S. conceived and designed the project. P.P. performed the bulk of the experimental work with significant help from V.W., C.H., A.T. and A-K.H. All authors participated in measurements and analysis of the data, discussed the results and took part in producing the manuscript.

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Correspondence to Wolfgang Schnick.

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The authors declare no competing financial interests.

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Pust, P., Weiler, V., Hecht, C. et al. Narrow-band red-emitting Sr[LiAl3N4]:Eu2+ as a next-generation LED-phosphor material. Nature Mater 13, 891–896 (2014). https://doi.org/10.1038/nmat4012

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