Robust moisture and thermally stable phosphor glass plate for highly unstable sulfide phosphors in high-power white light-emitting diodes

Lee, Jin Seok; Unithrattil, Sanjith; Kim, Sung Hoon; Lee, In Jae; Lee, Hyungeui; Im, Won Bin

doi:10.1364/ol.38.003298

Cited by 57 publications

(28 citation statements)

References 4 publications

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“…Lee et al [12] designed segmented PiGs with CASN:Eu 2 , but they can only be applied to large multi-chip LEDs since they need to be diced and reassembled. The intermixing of SrGa 2 S 4 :Eu 2 for green and CASN:Eu 2 was also reported [13] using SiO 2 -ZnO-B 2 O 3 glass, which can be sintered above 600°C. However, the CASN:Eu 2 phosphor starts to degrade at 600°C.…”

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confidence: 61%

“…As shown in the figure, the CASN:Eu 2 starts to lose its color and PL intensity from 600°C and drops thereafter. The oxidation of Eu 2 into Eu 3 and possible chemical decomposition of nitride phosphors at the sintering temperature are believed to be responsible for the thermal degradation [13,14]. This makes it hard to adjust the chromaticity of the PiGs with conventional glasses at sintering temperatures higher than 600°C.…”

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confidence: 99%

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Control of chromaticity by phosphor in glasses with low temperature sintered silicate glasses for LED applications

et al. 2014

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Phosphor-in-glass (PiG) color converters for LED applications were fabricated with a mixture of phosphors, Y₃Al₅O₁₂:Ce³⁺ (yellow) and CaAlSiN₃:Eu²⁺ (red). The low sintering temperature (550°C) of SiO₂-Na₂O-RO (R=Ba, Zn) glass powder enabled the inclusion of CaAlSiN₃:Eu²⁺ (red) phosphor which cannot be embedded with conventional glass powders for PiGs. By simply varying the mixing ratio of glass to phosphors as well as the ratio of yellow to red phosphors, the facile control of the CIE chromaticity coordinates and correlated color temperature of the LED following the Planckian locus has been achieved. Phosphors were well distributed within the glass matrix without noticeable reactions, preserving the enhanced thermal quenching property of the PiG compared to those with silicone resins, for LEDs.

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confidence: 61%

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Control of chromaticity by phosphor in glasses with low temperature sintered silicate glasses for LED applications

et al. 2014

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“…In addition, the fabrication of bulk luminescent material of millimeter thickness became not practically needed for a WLED. Therefore, the fabrication of inorganic luminescence layers by a single and cost‐efficient process supported by robust moisture and thermal stability is highly desirable in high‐power white light‐emitting diodes …”

Section: Introductionmentioning

confidence: 99%

Surface crystallized Mn‐doped glass‐ceramics for tunable luminescence

2019

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Monolithic luminescent glass‐ceramic is highly desirable for solid‐state lighting as it is stable and robust, while in practical light‐emitting devices only a thin luminescent layer is used for more efficient excitation and light extraction. In this paper, Mn2+‐doped glass and glass‐ceramic with the composition of 60SiO2‐8Na2O–20ZnO–12Ga2O3 were fabricated by the conventional melt‐quenching technique. We observe that the crystallization of α‐Zn2SiO4 nanocrystals takes place on the glass surface with controllable thickness after heat treatment. The glass samples show typical red emission peaking at λ = 620 nm that can be ascribed to the spin‐forbidden 4T1g(G) → 6A1g(S) transition of Mn2+ (d5) located in the octahedral coordination site of the glass host. After surface crystallization this red emission is retained and a new green emission at 528 nm is observed through the control of the crystallization temperature and duration, thus offering tunable emission characteristics promising for the lighting application. This change in the visible emission is interpreted in terms of the change of coordination state of Mn2+ from octahedral in a glass matrix to tetrahedral in the surface precipitated α‐Zn2SiO4 crystals.

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“…Therefore, not only YAG:Ce 3+ -based PiG but also PiG with phosphors of various emission wavelengths have been reported by many researchers. Lee et al 65 reported the feasibility of using PiG as an encapsulant for highly unstable SrGa 2 S 4 :Eu 2+ sulfide phosphors, which were not previously used in wLED applications because of high chemical instability. Zhu et al 66 developed a green PiG using β-SiAlON:Eu 2+ phosphor under various blue laser flux densities.…”

Section: Glass Phosphor Plate (Gpp)mentioning

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.

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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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Robust moisture and thermally stable phosphor glass plate for highly unstable sulfide phosphors in high-power white light-emitting diodes

Cited by 57 publications

References 4 publications

Control of chromaticity by phosphor in glasses with low temperature sintered silicate glasses for LED applications

Control of chromaticity by phosphor in glasses with low temperature sintered silicate glasses for LED applications

Surface crystallized Mn‐doped glass‐ceramics for tunable luminescence

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

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