The elevated colour rendering of white-LEDs by microwave-synthesized red-emitting (Li, Mg)3RbGe8O18:Mn4+ nanophosphors

2021 ◽  
Vol 50 (8) ◽  
pp. 3044-3059
Author(s):  
Malini Abraham ◽  
Arup K. Kunti ◽  
Thejas K.K. ◽  
Nuño Amador-Mendez ◽  
Noëlle Gogneau ◽  
...  
Keyword(s):  
White Led ◽  
Blue Led ◽  
White Leds ◽  
Colour Rendering

The bright red emitting (Li, Mg)3RbGe8O18:Mn4+ nanophosphors significantly enhanced the colour rendering of a white-LED based on blue-LED chip and YAG:Ce3+ phosphor.

Growth and Light Properties of Fluorescent SiC for White LEDs

2012 ◽  
Vol 717-720 ◽  
pp. 87-92
Author(s):  
Mikael Syväjärvi ◽  
Rositza Yakimova ◽  
Motoaki Iwaya ◽  
Tetsuya Takeuchi ◽  
Isamu Akasaki ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
White Light ◽  
Energy Savings ◽  
Red Light ◽  
Visible Range ◽  
White Led ◽  
Light Emitting ◽  
Blue Led ◽  
White Leds ◽  
New Type

The LED technology started to developed many years ago with red light emitting diodes. To achieve the blue LED, novel growth technologies and process steps were explored, and made it possible to demonstrate efficient blue LED performance from nitrides. The efficiency was further developed and blue LEDs were commercially introduced in the 1990’s. The white LED became possible by the use of the blue LED and a phosphor that converts a part of the blue light to other colors in the visible range to combine into white light. However, even today there are limitations in the phosphor-based white LED technology, in particular for general lighting, and new solutions should be explored to speed the pace when white LEDs will be able to make substantial energy savings. In this paper we overview gallium nitride materials evolution and growth concepts for LEDs. We describe the fluorescent silicon carbide material prepared by a novel growth technology for a new type of white LED in general lighting with pure white light. This paper introduces an interesting research in fundamental growth and optical properties of light emitting silicon carbide.

scholarly journals Stacked phosphor coating technology for white LEDs with high colour temperature and high colour rendering index

2017 ◽  
Vol 51 (1) ◽  
pp. 147-153 ◽  
Author(s):  
P Ge ◽  
Z Zhou ◽  
J Zhang ◽  
H Wang
Keyword(s):  
Light Sources ◽  
White Led ◽  
Phosphor Powder ◽  
Phosphor Layer ◽  
Coating Technology ◽  
Luminous Efficacy ◽  
Colour Temperature ◽  
White Leds ◽  
Phosphor Coating ◽  
Colour Rendering

Existing white LEDs use a blue LED chip to stimulate phosphor powder to form white light. The surface coated with a phosphor layer directly affects the colour rendering index, the luminous efficacy and the colour temperature. We have encapsulated a white LED source with chip-on-board packaging to meet the requirements for a high power, high colour temperature, high colour rendering index LED using stacked phosphor coating. This chip-on-board white LED light source can achieve a colour rendering index over 95 and a luminous efficacy over 100 lm/W while the colour temperature is 5700 K. This technology can be widely used in commercial lighting applications where high quality light sources are needed.

Tunable white light of a Ce3+,Tb3+,Mn2+ triply doped Na2Ca3Si2O8 phosphor for high colour-rendering white LED applications: tunable luminescence and energy transfer

2017 ◽  
Vol 46 (28) ◽  
pp. 9272-9279 ◽  
Author(s):  
Wei Lü ◽  
Huawei Xu ◽  
Jiansheng Huo ◽  
Baiqi Shao ◽  
Yang Feng ◽  
...  
Keyword(s):  
Energy Transfer ◽  
White Light ◽  
White Led ◽  
White Leds ◽  
Full Color ◽  
Color Rendering Index ◽  
Color Rendering ◽  
Colour Rendering

We report a full-color emitting Na2Ca3Si2O8:Ce3+,Tb3+,Mn2+ phosphor with a high color rendering index for UV white LEDs.

Study of High-Power White LED's Lifetime Based on Accelerated Life Test

2013 ◽  
Vol 800 ◽  
pp. 205-209 ◽  
Author(s):  
De Sheng Li ◽  
Nian Yu Zou ◽  
Yun Cui Zhang ◽  
Xiao Yang He ◽  
Yi Yang
Keyword(s):  
High Power ◽  
Accelerated Life Test ◽  
Reliability Test ◽  
White Led ◽  
Life Test ◽  
Arrhenius Model ◽  
White Leds ◽  
Accelerated Life ◽  
Temperature Levels

The study of LED reliability becomes more and more important with LED widely used in various areas, and accelerated life test (ALT) as an element of reliability test is widely used to predict the lifetime of LED. In this paper, ALTs have been carried out at various current levels and various temperature levels. In the current ALT experiment, three kinds of stressing currents were demonstrated for 1W white LEDs and lumen flux of the tested LEDs were studied, and based on Eyting model, lifetime of the tested LEDs is calculated about 6.86×105h. In the temperature ALT experiment, two kinds of stressing temperature were demonstrated for the same type of white LEDs and lumen flux were also studied, and based on Arrhenius model, lifetime of the tested LEDs is calculated about 7.41×105h. In addition, the color shifting velocity is faster than lumens depreciation velocity was observed in our experiment, which means the lifetime evaluating of white LED should be paid more attention.

An excellent cyan-emitting orthosilicate phosphor for NUV-pumped white LED application

2017 ◽  
Vol 5 (47) ◽  
pp. 12365-12377 ◽  
Author(s):  
Yongfu Liu ◽  
Jack Silver ◽  
Rong-Jun Xie ◽  
Jiahua Zhang ◽  
Huawei Xu ◽  
...  
Keyword(s):  
High Performance ◽  
Luminescence Properties ◽  
White Led ◽  
White Leds ◽  
Promising Application

The Ba9Lu2Si6O24:Ce3+cyan phosphor has excellent luminescence properties and displays promising application in NUV-based white LEDs with high performance.

scholarly journals Simultaneously Improve White LED Omni-Directional Package Efficacy and Spatial Color Uniformity on Scattered Photon Extraction Technology

Crystals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 21 ◽  
Author(s):  
Tsung-Xian Lee ◽  
Yun-Chieh Huang
Keyword(s):  
Extraction Efficiency ◽  
Critical Index ◽  
Light Extraction Efficiency ◽  
Color Temperature ◽  
Scattered Photon ◽  
Lens Design ◽  
White Led ◽  
Extraction Technology ◽  
White Leds ◽  
Color Uniformity

The Scattered Photon Extraction (SPE™) based on the concept of TIR lens combined with remote phosphor is proven to be one of the effective solutions for improving white LED efficiency, and it provides the omnidirectional light distribution for luminaire design. Not only the light extraction efficiency (LEE) is important, but also the angular uniformity of correlated color temperature (CCT) is a critical index in the evaluation of high-quality white LEDs. A non-optimized SPE™ will cause an increase in the angular CCT deviation (ACCTD) and ultimately affect lighting quality. Two possible ways using lens design are proposed to reduce the ACCTD and even improve its efficiency. Among them, using the concept of light guiding to design the lens can minimum the deviation of forward and backward CCT from 2720 K to 657 K, and the overall efficiency can be further enhanced by 12% compared to typical SPE™ lens.

Luminescence properties of Na2SiF6:Mn4+red phosphors for high colour-rendering white LED applications synthesized via a simple exothermic reduction reaction

2017 ◽  
Vol 1 (5) ◽  
pp. 928-932 ◽  
Author(s):  
Tian-Chun Lang ◽  
Tao Han ◽  
Ling-Ling Peng ◽  
Ming-Jing Tu
Keyword(s):  
Emission Spectra ◽  
Reduction Reaction ◽  
Luminescence Properties ◽  
White Led ◽  
Red Emission ◽  
Red Phosphors ◽  
Colour Rendering

Na2SiF6:Mn4+red phosphors were synthesizedviaa simple exothermic reduction reaction, and produced a sharp red emission spectra.

Narrow band red emitting europium complexes and their application in smart white LEDs and vapoluminescent sensors

2020 ◽  
Vol 49 (19) ◽  
pp. 6205-6219 ◽  
Author(s):  
Rachna Devi ◽  
Sivakumar Vaidyanathan
Keyword(s):  
Narrow Band ◽  
White Led ◽  
Acid Base ◽  
Europium Complexes ◽  
White Leds ◽  
Color Rendering Index ◽  
Color Rendering

The synthesized molecular Eu-complex based hybrid white LED showed superior color rendering index. In addition, the complex also showed on-off-on luminescence with exposure to acid–base vapours.

scholarly journals New paradigm of multi-chip white LEDs: combination of an InGaN blue LED and full down-converted phosphor-converted LEDs

2011 ◽  
Vol 19 (S3) ◽  
pp. A270 ◽  
Author(s):  
Ji Hye Oh ◽  
Jeong Rok Oh ◽  
Hoo Keun Park ◽  
Yeon-Goog Sung ◽  
Young Rag Do
Keyword(s):  
New Paradigm ◽  
Blue Led ◽  
White Leds
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