YAG glass-ceramic phosphor for white LED (II): luminescence characteristics

Tanabe, Setsuhisa; Fujita, Sakae; Yoshihara, Shizue; Sakamoto, Akihiko; Yamamoto, Shigeru

doi:10.1117/12.614681

Cited by 88 publications

(34 citation statements)

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“…The original nanostructure of the biphasic YAG-Al 2 O 3 ceramics may explain the high quantum efficiency by strong confinement effects which induce high luminous efficiency 57,58 . The QE is much superior to that of conventional SiO 2 -based YAG transparent glass-ceramics (about 30%) 34 . The high QE of the material can also be linked to the high crystalline quality of the YAG nanocrystals in the YAG-Al 2 O 3 composite ceramic 59 .…”

Section: Resultsmentioning

confidence: 81%

“…Unfortunately, in addition to the complex elaboration of stoichiometric Y 3 Al 5 O 12 glass bulk 29,30 , the large density difference between the glass (∼4.08 g/cm 3 ) 31 and the crystalline (4.55 g/cm3) YAG phases prevents transparency to be retained during crystallization using a full and congruent crystallization from glass approach 32 . This is the reason why Tanabe et al developed transparent YAG glass-ceramics 33,34 .…”

Section: Introductionmentioning

confidence: 99%

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Pressureless glass crystallization of transparent yttrium aluminum garnet-based nanoceramics

et al. 2018

Nat Commun

138

111

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Transparent crystalline yttrium aluminum garnet (YAG; Y3Al5O12) is a dominant host material used in phosphors, scintillators, and solid state lasers. However, YAG single crystals and transparent ceramics face several technological limitations including complex, time-consuming, and costly synthetic approaches. Here we report facile elaboration of transparent YAG-based ceramics by pressureless nano-crystallization of Y2O3–Al2O3 bulk glasses. The resulting ceramics present a nanostructuration composed of YAG nanocrystals (77 wt%) separated by small Al2O3 crystalline domains (23 wt%). The hardness of these YAG-Al2O3 nanoceramics is 10% higher than that of YAG single crystals. When doped by Ce3+, the YAG-Al2O3 ceramics show a 87.5% quantum efficiency. The combination of these mechanical and optical properties, coupled with their simple, economical, and innovative preparation method, could drive the development of technologically relevant materials with potential applications in wide optical fields such as scintillators, lenses, gem stones, and phosphor converters in high-power white-light LED and laser diode.

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Section: Resultsmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Pressureless glass crystallization of transparent yttrium aluminum garnet-based nanoceramics

et al. 2018

Nat Commun

138

111

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“…Developing a pre-fabricated phosphor layer and then coating it on the chip may present better mechanical reliability. Approaches include Lumiramic technology invented by Lumileds [108], glass-ceramic phosphor [109,110] and thin film of pre-cured phosphor silicone (TFP) studied by our research group. Lumiramic and glass-ceramic techniques embed phosphor particles in transparent ceramics.…”

Section: Prospectmentioning

confidence: 99%

Status and prospects for phosphor-based white LED packaging

Liu

Wang

et al. 2009

Front. Optoelectron. China

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The status and prospects for high-power, phosphor-based white light-emitting diode (LED) packaging have been presented. A system view for packaging design is proposed to address packaging issues. Four aspects of packaging are reviewed: optical control, thermal management, reliability and cost. Phosphor materials play the most important role in light extraction and color control. The conformal coating method improves the spatial color distribution (SCD) of LEDs. High refractive index (RI) encapsulants with high transmittance and modified surface morphology can enhance light extraction. Multi-phosphor-based packaging can realize the control of correlated color temperature (CCT) with high color rendering index (CRI). Effective thermal management can dissipate heat rapidly and reduce thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE). Chip-on-board (CoB) technology with a multilayer ceramic substrate is the most promising method for high-power LED packaging. Low junction temperature will improve the reliability and provide longer life. Advanced processes, precise fabrication and careful operation are essential for high reliability LEDs. Cost is one of the biggest obstacles for the penetration of white LEDs into the market for general illumination products. Mass production in terms of CoB, system in packaging (SiP), 3D packaging and wafer level packaging (WLP) can reduce the cost significantly, especially when chip cost is lowered by using a large wafer size.

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“…Several previous studies have investigated light propagation in a phosphor medium and different assumptions were used in simulating phosphor scattering such as isotropic scattering, random scattering, and Mie scattering. [2][3][4][5][6][7] However, the majority of these studies lack supporting experimental data to validate their models. Among those who supplied experimental results, their experimental setup share similar problems-the incident light only covers several discrete wavelengths; the transmitted light and reflected light are not measured simultaneously so the light source fluctuations were not excluded from the analysis; the cross talk between integrating spheres (if two such spheres were used) was ignored.…”

Section: Introductionmentioning

confidence: 99%

Phosphor modeling and characterization

Jenkins

2014

Opt. Eng

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Abstract. The prevalent method to develop a phosphor recipe (based on trial and error) to create white light with a blue light-emitting diode (LED) is time-consuming. We developed a new method for determining parametric values in a simulated phosphor model through systematic testing of phosphor samples and optimizing the parameter values with ray-trace software. The model employs Mie volume scattering together with absorption and down-conversion. A double-integrating sphere spectral measurement system was constructed to perform phosphor characterization. It was used to characterize a YAG phosphor over a wide range of phosphor concentrations and thicknesses. The final phosphor model was proven to accurately predict the phosphor performance. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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YAG glass-ceramic phosphor for white LED (II): luminescence characteristics

Cited by 88 publications

References 1 publication

Pressureless glass crystallization of transparent yttrium aluminum garnet-based nanoceramics

Pressureless glass crystallization of transparent yttrium aluminum garnet-based nanoceramics

Status and prospects for phosphor-based white LED packaging

Phosphor modeling and characterization

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