Luminescence properties and warm white LED application of a ternary-alkaline fluoride red phosphor K2NaAlF6:Mn4+

Author(s): L. Y. Wang ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , E. H. Song ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , T. T. Deng ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Y. Y. Zhou ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Z. F. Liao ⁶ ^, ⁷ ^, ⁸ ^, ⁵ , W. R. Zhao ⁶ ^, ⁷ ^, ⁸ ^, ⁵ , B. Zhou ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Q. Y. Zhang ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵

Publication date (Electronic): 2017

Journal: Dalton Transactions

Publisher: Royal Society of Chemistry (RSC)

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Abstract

Electroluminescence spectra and a photograph of a LED device featuring K ₂NaAlF ₆:Mn ⁴⁺ under 20 mA drive current as well as a CIE chromaticity diagram for the WLED.

Abstract

Herein, a Mn ⁴⁺ ion doped complex ternary-alkaline fluoride red phosphor K ₂NaAlF ₆:Mn ⁴⁺ has been synthesized through a facile two-step co-precipitation method at room temperature. The crystal structure, morphological properties and influence of the dopant concentration, temperature and humidity on luminescence properties as well as the performance of the as-synthesized phosphor used in white light emitting diodes (WLEDs) were investigated carefully. Intense absorption in the blue region (∼460 nm) and bright narrow-band red emission (∼630 nm) with high color purity were observed from this resultant powder. Temperature-dependent investigation and reliability examination in a HTHH environment (85 °C high temperature and 85% high humidity) indicate that the obtained ternary-alkaline fluoride phosphor K ₂NaAlF ₆:Mn ⁴⁺ presents more exceptional thermal quenching behavior and longevity compared to some other binary-alkaline fluorides. Moreover, using K ₂NaAlF ₆:Mn ⁴⁺ as a red light component, a warm WLED with a preferable color rendering index ( R _a = 85.5) and luminous efficacy (LE = 91.2 lm W ⁻¹) as well as a low corresponding color temperature (CCT = 3650 K) is easily achieved, further revealing the great potential of the as-prepared ternary-alkaline fluoride red phosphor K ₂NaAlF ₆:Mn ⁴⁺ for WLED applications.

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Advances in Phosphors for Light-emitting Diodes.

Lupin Chun-Che Lin, Ru-Shi Liu (2011)

Light-emitting diodes (LEDs) are excellent candidates for general lighting because of their rapidly improving efficiency, durability, and reliability, their usability in products of various sizes, and their environmentally friendly constituents. Effective lighting devices can be realized by combining one or more phosphor materials with chips. Accordingly, it is very important that the architecture of phosphors be developed. Although numerous phosphors have been proposed in the past several years, the range of phosphors that are suitable for LEDs is limited. This work describes recent progress in our understanding of the prescription, morphology, structure, spectrum, and packaging of such phosphors. It suggests avenues for further development and the scientific challenges that must be overcome before phosphors can be practically applied in LEDs.