Long-Term Stable, Low-Temperature Remote Silicate Phosphor Thick Films Printed on a Glass Substrate

Kim, Jun Sik; Kwon, Oh Hyeon; Jang, Jin Woo; Lee, Sung Hyun; Han, Sung‐Jun; Lee, Joo Hong; Cho, Yong Soo

doi:10.1021/co500169t

Cited by 31 publications

(20 citation statements)

References 27 publications

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“…Nonconventional ideas to enhance the luminescence performance of, specifically, the remote structure have been recently reported in various ways. They include new low‐cost phosphor layers, glass‐involved phosphor pellets, printing/coating techniques, and new phosphor structures for better performance of white LED structures. However, there have been limited improvements in luminous efficacy, which still remains a serious challenge hindering commercial success.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Luminescence Characteristics of Remote Yellow Silicate Phosphors Printed on Nanoscale Surface‐Roughened Glass Substrates for White Light‐Emitting Diodes

Kim

Eswaran

Kwon

et al. 2016

Advanced Optical Materials

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techniques, [ 6,13,16 ] and new phosphor structures [ 17,18 ] for better performance of white LED structures. However, there have been limited improvements in luminous effi cacy, which still remains a serious challenge hindering commercial success.Trapped loss of light in the air-gap (due to backward photons) and total internal refl ection (TIR) arising within the remote structure are the main factors that critically limit the light extraction. [19][20][21] The reported earlier methods such as scattered photon extraction [ 22 ] and diffused refl ection cup approach [ 23 ] have mainly improved the extraction of back refl ected light. By contrast, few studies to enhance the luminous effi cacy by reducing the TIR in the phosphor part have been reported. Our approach in this study is to adopt a simple nanoscale surface roughening technique to enhance the luminous efficacy by minimizing the TIR at the air-phosphor layer and airglass substrate interface of a remote phosphor LED consisting of yellow phosphor screen-printed on a glass substrate. In the past, surface roughening or surface texturing approaches have been applied to the top n-GaN layer of blue InGaN LED chips to enhance blue light emission by minimizing TIR at the semiconductor-air interface. [24][25][26] Notwithstanding the promising results of surface roughening methods, there have been very limited reports on the deployment of surface texturing techniques for the phosphor layer. One related report is about the random texturing in the case of yttrium aluminum garnet (YAG) phosphor by means of an imprint technique which resulted in an increased luminous fl ux by ≈5.4%. [ 27 ] A patterned YAG phosphor created by pulsed spray coating on a transparent silicone encapsulant resin using a circular mask was reported without increasing the luminous effi cacy. [ 28 ] In this work, we explore a simple surface roughening technique of the glass substrate used as a base for printable remote silicate phosphor, (Ba,Sr,Ca) 2 SiO 4 :Eu 2+ , for the purpose of enhancing the luminescence performance. Compared to other YAG-based phosphors, this yellow silicate phosphor is known to possess higher luminous effi cacy and to have advantages in commercial utilization and cost-effectiveness. We recently reported the utilization of a glass substrate for printable silicate Nonconventional ways to modify phosphor structures have been reported to enhance the overall luminous effi cacy of white light-emitting diodes (LED). Here, a nanoscale texturing technique of a glass substrate with the simple printing process of yellow (Ba,Sr,Ca) 2 SiO 4 :Eu +2 silicate phosphor paste is combined to achieve enhanced white luminescence performance. It is demonstrated that the luminous effi cacy of the resulting printed phosphor layer can be enhanced by ≈16% as a result of controlling surface roughness of the substrate up to 151 nm. The substantial improvement obtained by texturing both sides of the substrate is attributed to the reduction of total internal refl ection of rays at the glass-air interfac...

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Section: Introductionmentioning

confidence: 99%

Enhanced Luminescence Characteristics of Remote Yellow Silicate Phosphors Printed on Nanoscale Surface‐Roughened Glass Substrates for White Light‐Emitting Diodes

Kim

Eswaran

Kwon

et al. 2016

Advanced Optical Materials

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“…The improved thermal stability of the PiG plates in comparison to those prepared with commercial silicon resin was confirmed by measuring the thermal quenching property, which had not previously been properly addressed for PiG thick films . The inset in Figure shows the thermal quenching property of the present thick films, which was recorded with relative PL intensity for varying temperatures.…”

Section: Cri Cct Efficacy and Thickness Of Pig Thick Films With Vamentioning

confidence: 70%

“…In film form, however, PiG does not require postprocessing and can be applied to various surfaces providing high versatility in design and pattern formation. These advantageous features and the versatility of the screen printing method used to fabricate it increase the feasibility of using PiG in applications . Chae et al .…”

Section: Cri Cct Efficacy and Thickness Of Pig Thick Films With Vamentioning

confidence: 99%

“…In order to improve CRI for thick film applications, it is important to introduce a commercial red phosphor such as CaAlSiN 3 :Eu 2+ (CASN:Eu 2+ ) using glass with a low sintering temperature, as CASN:Eu 2+ is thermally damaged above 600°C . Fabricating PiG thick films using UV‐curable polymer and low sintering temperature glass have been suggested as ways to embed thermally weak silicate phosphors. However, the polymer matrix is expected to show a thermal degradation similar to that of the organic resin used for conventional white LEDs.…”

Section: Cri Cct Efficacy and Thickness Of Pig Thick Films With Vamentioning

confidence: 99%

“…However, the polymer matrix is expected to show a thermal degradation similar to that of the organic resin used for conventional white LEDs. In addition, their low sintering temperature glass based on Bi 2 O 3 ‐ZnO‐B 2 O 3 has visible absorption due to multivalent Bi‐ions, which hinders practical applications in addition to their low luminous efficacy . Thus, it is crucial to have a transparent low sintering temperature glass without heavy‐metal ions for PiG thick film formation.…”

Section: Cri Cct Efficacy and Thickness Of Pig Thick Films With Vamentioning

confidence: 99%

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Phosphor‐in‐glass thick film formation with low sintering temperature phosphosilicate glass for robust white LED

et al. 2017

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Phosphor-in-glass (PiG) thick film was fabricated on a borosilicate glass substrate using a conventional screen printing method and employing phosphosilicate glass to allow low-temperature sintering. The vehicle content and sintering temperature were optimized to form a thick film with a thickness of~50 lm. Commercial yellow (Y 3 Al 5 O 12 :Ce 3+ ) and red (CaAlSiN 3 :Eu 2+ ) phosphors were successfully incorporated within the glass matrix and then sintered at 550°C. Color-tunable white LEDs were achieved using the PiG thick films as a color converter by varying the glass to phosphor (GtP) ratio. The high luminous efficacy of up tõ 120 lm/W and high color rendering index of up to 89 in combination with the thermal quenching property prove the practical feasibility of the PiG thick films for high-power/high-brightness LED applications. K E Y W O R D S glass, luminescence, phosphors, thick films

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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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Long-Term Stable, Low-Temperature Remote Silicate Phosphor Thick Films Printed on a Glass Substrate

Cited by 31 publications

References 27 publications

Enhanced Luminescence Characteristics of Remote Yellow Silicate Phosphors Printed on Nanoscale Surface‐Roughened Glass Substrates for White Light‐Emitting Diodes

Enhanced Luminescence Characteristics of Remote Yellow Silicate Phosphors Printed on Nanoscale Surface‐Roughened Glass Substrates for White Light‐Emitting Diodes

Phosphor‐in‐glass thick film formation with low sintering temperature phosphosilicate glass for robust white LED

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

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