Facile one-step fabrication of 2-layered and 4-quadrant type phosphor-in-glass plates for white LEDs: an insight into angle dependent luminescence

Kim, Eden; Unithrattil, Sanjith; Sohn, In Seong; Kim, Seung Jun; Chung, Woon Jin; Im, Won Bin

doi:10.1364/ome.6.000804

Cited by 43 publications

(27 citation statements)

References 16 publications

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“…The distinguishable emission bands from the component phosphors are clearly observed when using this phosphor geometrical design; while the green emission is merged into the broad band peaking in the red region when using the conventional phosphor mixing design, confirming the photon reabsorption can be greatly reduced in the former case. In the further work, they proposed a facile one‐step fabrication technique to eliminate the interfacial layer between alternate quadrants and hence the leakage of light through this layer . Figure a exhibits the digital photograph of the one‐step fabricated GCs and their luminescent photographs on state.…”

Section: Materials Systemsmentioning

confidence: 99%

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Glass Ceramic Phosphors: Towards Long‐Lifetime High‐Power White Light‐Emitting‐Diode Applications–A Review

Lin

Cheng

et al. 2018

Laser & Photonics Reviews

290

124

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With the technological advancements of high‐quality lightings and high‐end displays, white light‐emitting‐diodes (w‐LEDs) are quickly developing towards high energy density excitation, high output power and high device stability, which requires outstanding thermal properties of the phosphor color converters. In this connection, all‐inorganic luminescent glass ceramic (GC), exhibiting excellent physical/chemical stability to address the serious aging and yellowing issues of conventional phosphor/silicone composite, receives great attention recently and is regarded as a new generation color converter with longevity. Herein, a thorough survey of the research progress of this kind of material is made, with focus put on the design principle, microstructure‐property relationship, packaging technology and the burgeoning application direction. Some challenging issues are discussed and potential directions are suggested for further developing the phosphor‐glass composite fulfilling various requirements in practical application. This Review can promote rapid progress of long‐lifetime high‐power w‐LEDs.

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Section: Materials Systemsmentioning

confidence: 99%

“…b) Corresponding EL spectra obtained under 350 mA and 20 V. c) CIE‐1931 chromaticity coordinates of the constructed warm w‐LED. Reproduced with permission . Copyright 2015, American Optical Society.…”

Section: Materials Systemsmentioning

confidence: 99%

Glass Ceramic Phosphors: Towards Long‐Lifetime High‐Power White Light‐Emitting‐Diode Applications–A Review

Lin

Cheng

et al. 2018

Laser & Photonics Reviews

290

124

View full text Add to dashboard Cite

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“…The report showed that the total emission intensity of the onestep fabricated PiG was enhanced by about 112%. 86 Peng et al Control of pore in phosphor plate and particle size of phosphor.-In wLEDs, the residual porosity in the phosphor plate is a critical factor determining the efficacy, color coordinates, and color angular shift of the light emitted by the LED units. As a result of the sintering process, the porosity of the plate decreases and the transmission of the blue component increases.…”

Section: Aspects Of Improvement For High-power Applicationsmentioning

confidence: 99%

Review—Phosphor Plates for High-Power LED Applications: Challenges and Opportunities toward Perfect Lighting

Kim

Viswanath

Unithrattil

et al. 2017

ECS J. Solid State Sci. Technol.

Self Cite

127

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In the past decades, solid-state lighting based on phosphors as energy converters has been a fast-growing industry. Phosphorconverted white light-emitting diodes (pc-wLEDs) enable high-power applications and miniaturization; for this, the phosphor must have good stability and high efficiency. In order to satisfy this demand, phosphor plates have been proposed instead of conventional organic-based phosphor binders. In this review, such phosphor plates are categorized according to their synthesis methods, and the advantages and disadvantages of each category are detailed. In addition, we describe the major aspects of phosphor plates that require improvement for applications in high-power devices. For the fabrication of high-power LEDs, the phosphor configuration, color purity, porosity, and particle size of glass powders are key properties to enhance the luminescence efficiency and reduce the generation of heat inside wLED packages, thereby improving thermal stability. The advent of authentic, energy-efficient lighting in the home and workplace significantly affected the modern way of life. Beginning with the mass production of incandescent light bulbs, and with the subsequent evolution of fluorescence lights, lighting technology has developed rapidly in the last few decades. Since Edison's incandescent bulb in 1879, 1 artificial lighting has been developed to increase power output and decrease the size of the system. The development of red light-emitting diodes (LEDs) in 1962 2 and blue LEDs in 1993 3 allowed innovation in lighting and display. In particular, combinations of blue LEDs and yellow phosphors are used for many applications because they can realize cheap and efficient white solid-state lighting with several advantages including long lifetimes, eco-friendly behavior, and the capacity of miniaturization. 4-6In phosphor-converted white LEDs (pc-wLEDs), the phosphor converter dispersed in silicon resin (phosphor-in-silicon; PiS) is directly packed on a blue InGaN chip.7 When driven by a bias current, the emitted blue light absorbed by the phosphor is emitted as yellow light; together with the transmitted blue light, this constitutes white luminescence. However, this method lacks a red component, which entails the drawbacks of a poor color rendering index (CRI) and limited correlated color temperature (CCT). To overcome these drawbacks, one proposed method mixes yellow phosphors with phosphors having green to red emissions under blue excitation. 8 In pc-wLEDs, the color is primarily determined by the ratio of the blue emission from the LED chip to the yellow to red emission from the phosphor. However, the efficacy and brightness are determined by the converted yellow to red emission, as it contributes the bulk of lumens. In this configuration, the heat generated from the LED chip and phosphor cannot be efficiently dissipated because of the poor thermal stability and weak thermal conductivity of the resin, which causes luminous decay and color shifting in white light-emitting diodes (wLEDs).9 When the tempe...

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“…However, heat generated from high‐power LEDs may lead to yellowing, carbonization, and browning of the encapsulant and thus change the color temperature of the WLED and decrease its luminous efficacy. Different techniques have emerged to overcome these drawbacks, among these we find approaches such as glass‐ceramics, and phosphor in glass (PIG) . A PIG is formed by mixing a transparent glass powder with a phosphor material, and then the green body is sintered at a certain temperature, usually below 800°C.…”

Section: Introductionmentioning

confidence: 99%

“…Several approaches have been proposed to increase CRI value in PIGs, including randomly mixing glass and yellow phosphor with red phosphor, codoping YAG:Ce 3+ with Mn 2+ , embedding YAG in doped glass with Eu, creating alternated sections of yellow phosphor and red phosphor with circular section patterns, applying a thin red layer by screen printing, mixing both yellow and red phosphor and incorporate them on top of a glass via screen printing and recently creating alternated yellow and red sections by screen printing . CaAlSiN 3 :Eu 2+ (CASN:Eu 2+ ) is one of the most used phosphors with red emission .…”

Section: Introductionmentioning

confidence: 99%

Eu³⁺‐doped glass as a color rendering index enhancer in phosphor‐in‐glass

et al. 2018

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A new method for improving color rendering index (CRI) and low correlated color temperature (CCT) in high‐power white‐light‐emitting diodes (WLEDs) is proposed. We used a configuration of phosphor‐in‐glass (PIG) and studied light output changes with the increment in concentration of yellow‐emitting Y3Al5O12:Ce3+ (YAG:Ce3+) phosphor. The PIG was coupled on the top of blue‐light‐emitting diodes (LED) chip (465 nm). To compensate the lack of red emission in the phosphor, Eu3+‐doped tellurium glass with different europium content was employed as a red emitter. The suitable contents of YAG:Ce3+ and Eu3+ were 7.5 weight percent (wt%) and 3 mol percent (mol%), respectively. The CRI value went from 72 to 82, whereas the CCT was reduced from 24 933 to 6434 K. The proposed structure can improve CCT as well as CRI of WLEDs just by placing a glass on top.

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Facile one-step fabrication of 2-layered and 4-quadrant type phosphor-in-glass plates for white LEDs: an insight into angle dependent luminescence

Cited by 43 publications

References 16 publications

Glass Ceramic Phosphors: Towards Long‐Lifetime High‐Power White Light‐Emitting‐Diode Applications–A Review

Glass Ceramic Phosphors: Towards Long‐Lifetime High‐Power White Light‐Emitting‐Diode Applications–A Review

Review—Phosphor Plates for High-Power LED Applications: Challenges and Opportunities toward Perfect Lighting

Eu³⁺‐doped glass as a color rendering index enhancer in phosphor‐in‐glass

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Facile one-step fabrication of 2-layered and 4-quadrant type phosphor-in-glass plates for white LEDs: an insight into angle dependent luminescence

Cited by 43 publications

References 16 publications

Glass Ceramic Phosphors: Towards Long‐Lifetime High‐Power White Light‐Emitting‐Diode Applications–A Review

Glass Ceramic Phosphors: Towards Long‐Lifetime High‐Power White Light‐Emitting‐Diode Applications–A Review

Review—Phosphor Plates for High-Power LED Applications: Challenges and Opportunities toward Perfect Lighting

Eu3+‐doped glass as a color rendering index enhancer in phosphor‐in‐glass

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Eu³⁺‐doped glass as a color rendering index enhancer in phosphor‐in‐glass