Using rare earth doped thiosilicate phosphors in white light emitting LEDs: Towards low colour temperature and high colour rendering

Smet, Philippe; Korthout, Katleen; Haecke, Jo E. Van; Poelman, Dirk

doi:10.1016/j.mseb.2007.07.042

Cited by 84 publications

(51 citation statements)

References 15 publications

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“…Several ternary sulfide compounds have also been proposed as LED phosphor, with especially the thiogallates receiving some attention due to much better stability than for instance the thioaluminates (in casu green-emitting SrGa 2 S 4 :Eu 2+ [37,38,71] choosing the alkaline earth ion (Ca, Sr, Ba) and the dopant ion (Ce, Eu) [144]. A drawback is the relatively low thermal quenching temperature, typically in the 400 to 450K range.…”

Section: Sulfides and Oxysulfidesmentioning

confidence: 99%

Selecting Conversion Phosphors for White Light-Emitting Diodes

Smet

Parmentier

Poelman

2011

J. Electrochem. Soc.

703

501

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Light emitting diodes (LEDs) are on the verge of a breakthrough in general lighting, due to their rapidly improving efficiency. Currently, white LEDs with high color rendering are mainly based on wavelength conversion by one or more phosphor materials. This Review first describes how to quantify the quality of a light source, discussing the color rendering index (CRI) and alternative color quality indices. Then, six main criteria are identified and discussed, which should be fulfilled by a phosphor candidate to be considered for actual application in LEDs. These criteria deal with the shape and position of the emission and the excitation spectra, the thermal quenching behavior, the quantum efficiency, the chemical and thermal stability and finally with the occurrence of saturation effects. Based on these criteria, the most common dopant ions (broad-band emitting Eu AbstractLight emitting diodes (LEDs) are on the verge of a breakthrough in general lighting, due to their rapidly improving efficiency. Currently, white LEDs with high color rendering are mainly based on wavelength conversion by one or more phosphor materials. This Review first describes how to quantify the quality of a light source, discussing the color rendering index (CRI) and alternative color quality indices. Then, six main criteria are identified and discussed, which should be fulfilled by a phosphor candidate to be considered for actual application in LEDs. These criteria deal with the shape and position of the emission and the excitation spectra, the thermal quenching behavior, the quantum efficiency, the chemical and thermal stability and finally with the occurrence of saturation effects. Based on these criteria, the most common dopant ions (broad-band emitting Eu

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Section: Sulfides and Oxysulfidesmentioning

confidence: 99%

Selecting Conversion Phosphors for White Light-Emitting Diodes

Smet

Parmentier

Poelman

2011

J. Electrochem. Soc.

703

501

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“…Europium doped sulfide phosphors have gained renewed attention as alternatives for oxide phosphors, because they are more suited to obtain saturated red emission [2]. The thiosilicate materials Ba 2 SiS 4 [3] and Ca 2 SiS 4 [3,4] were recently investigated for use as phosphor hosts in white phosphor…”

Section: Introductionmentioning

confidence: 99%

Structure and luminescence of (Ca,Sr)₂SiS₄ : Eu²⁺ phosphors

Parmentier¹,

Smet²,

Bertram³

et al. 2010

J. Phys. D: Appl. Phys.

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Sr 2 SiS 4 :Eu 2+ , Ca 2 SiS 4 :Eu 2+ and the solid solution of both, europium-doped (Ca,Sr) 2 SiS 4 , were investigated as UV-VIS excitable green to red powder phosphors. Sr 2 SiS 4 :Eu 2+ shows two emission bands, peaking at 480 nm and 550 nm. By changing the ratio between Ca 2+ and Sr 2+ , the photoluminescent emission spectrum can be tuned. Using X-ray diffraction, the phase composition and lattice parameters of the thiosilicate compounds were determined. The material forms a single, monoclinic Sr 2 SiS 4 -like phase up to 40% substitution of Sr 2+ by Ca 2+ . From 50% to 90% of substitution by Ca 2+ , phase separation was observed, leading to more complex emission spectra.These spectra were studied in detail using photoluminescence spectroscopy, cathodoluminescence microscopy and temperature dependent optical measurements. The thermal quenching temperature decreases from 470 K in Ca 2 SiS 4 :Eu 2+ to 380 K in Sr 2 SiS 4 :Eu 2+ upon increasing substitution of Ca 2+ by Sr 2+ . The possibilities of these materials as wavelength converters for white LEDs were evaluated.

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“…[18][19][20] As for the sulfides, a very comprehensive review concerning their optical properties and suitability for LED application has been published recently 21 and recent advances in materials, techniques and properties of phosphors in phosphors-converted white light-emitting diodes have been summarized. 22 23 Exploring new types of sulfides with good thermal stability such as thiogallates might be a new direction. Moreover, sulfides with different cation sites may give the solution of wide spectral dispersion in the green and red region.…”

mentioning

confidence: 99%

Circadian Light Source Based on K_xNa_1-xLuS₂:Eu²⁺ Phosphor

Jarý¹,

Havlák²,

Bárta³

et al. 2017

ECS J. Solid State Sci. Technol.

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The presented work describes a functional demonstration device representing the source of white light with tunable color correlated temperature. Tunability is achieved by using two different kinds of excitation diodes (nearUV and blue) in combination with a proper K x Na 1-x LuS 2 :Eu 2+ phosphor. Its luminescence due to the Eu 2+ 5d-4f allowed transition covers a broad emission region in visible range under both nearUV and blue excitations. The possibility to change the intensity ratio of the excitation diodes yields the changes of the output color correlated temperature. These changes are clearly demonstrated by shifts in the CIE color space; light quality is also quantified and discussed using CRI (color rendering index) and CQS (color quality scale) metrics.

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Using rare earth doped thiosilicate phosphors in white light emitting LEDs: Towards low colour temperature and high colour rendering

Cited by 84 publications

References 15 publications

Selecting Conversion Phosphors for White Light-Emitting Diodes

Selecting Conversion Phosphors for White Light-Emitting Diodes

Structure and luminescence of (Ca,Sr)₂SiS₄ : Eu²⁺ phosphors

Circadian Light Source Based on K_xNa_1-xLuS₂:Eu²⁺ Phosphor

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Using rare earth doped thiosilicate phosphors in white light emitting LEDs: Towards low colour temperature and high colour rendering

Cited by 84 publications

References 15 publications

Selecting Conversion Phosphors for White Light-Emitting Diodes

Selecting Conversion Phosphors for White Light-Emitting Diodes

Structure and luminescence of (Ca,Sr)2SiS4 : Eu2+ phosphors

Circadian Light Source Based on KxNa1-xLuS2:Eu2+ Phosphor

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Product

Resources

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Structure and luminescence of (Ca,Sr)₂SiS₄ : Eu²⁺ phosphors

Circadian Light Source Based on K_xNa_1-xLuS₂:Eu²⁺ Phosphor