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Articles de revues sur le sujet « Pc-WLEDs »

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Auteur : Grafiati

Publié le 16 septembre 2023

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1

Thuy My, Le Thi, My Hanh Nguyen Thi et Hoang Thinh Nhan. « Yellow-green emitting CaGa2S4:Eu2+ phosphor : an application for enhancing the luminous flux of the white light emitting diodes ». Indonesian Journal of Electrical Engineering and Computer Science 32, n^o 1 (1 octobre 2023) : 90. http://dx.doi.org/10.11591/ijeecs.v32.i1.pp90-97.

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The <span lang="EN-GB">optimal spectral characteristics and photometric qualities in white-emitting light-emitting diodes (WLEDs) featuring red-emitting LEDs instead of phosphor (pc/R-WLEDs) were determined using the luminescent efficiency (LE) theory. The color quality scale (Rf) is higher than 97K for correlating color temperature (CCTs) ranging between 2700K and 6500K. We first identified genuine pc/R-WLEDs having Rf levels at 96–97, LE levels at 120–124 lm/W with CCT levels at 2969K, 4468K, 5682K, as well as 6558K with the utilization of all four-color phosphors: blues (448 nm), reddish (650 nm) LEDs, greenish (507 nm), and yellowish (586 nm). When compared to phosphorus-converted white-emitting LEDs (pc-WLEDs) and quantum dots white-emitting LEDs (QD-WLEDs), the pc/R-WLEDs, rather than the QD-WLED, would make better representatives of improved color version, notably in the reduced color temperatures, and could eventually replace current pc-WLEDs</span>.

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Dang Huu, Phuc, Nguyen Le Thai et Phan Xuan Le. « Studying CdS:In green phosphor's impacts on white-light emitting diode with higher luminous flux ». Materials Science-Poland 40, n^o 2 (1 août 2022) : 159–69. http://dx.doi.org/10.2478/msp-2022-0014.

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Abstract A lumen efficiency (LE) simulation model with the Monte Carlo method is introduced to the white-light-emitting diode devices that utilize the red LED (light-emitting diode) dyes instead of red-emitting phosphors (R-WLEDs). By simulating this model, the desirable spectrum-related indices and photometric efficiencies, which are adequate for superior chromatic consistency (or R f > 97), can be accomplished for R-WLEDs under the correlated color temperature (CCT) range of 5000–8000 K. The structure of the R-LED has LEDs in red and blue colors (650 nm and 448 nm) combined with phosphors possessing yellow and green emissions (586 nm and 507 nm). In comparison with pc-WLEDs (WLEDs operating with conversion phosphors) and QD-WLEDs (WLED devices with quantum dots), pc/R-WLED devices could present its outperformance to the others and become a promising way to achieve remarkable chromatic generation, particularly under the condition of small color temperature limit, and act as a substitute for the pc-WLED devices.

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Dang, Huu Phuc, Nguyen Thi Phuong Loan, Thanh Tung Nguyen et Sang Dang Ho. « Applying calcium fluoride and silica particles : A solution to improve color homogeneity of pc-WLEDS ». International Journal of Electrical and Computer Engineering (IJECE) 11, n^o 5 (1 octobre 2021) : 3864. http://dx.doi.org/10.11591/ijece.v11i5.pp3864-3869.

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<span>This article focuses on enhancing the lighting efficiency of pc-WLEDs, a new and advanced lighting solution that has received lots of attention. To adapt to the demand of modern lighting, the lighting performance of pc-WLEDs must be improved, especially the color homogeneity and luminous flux, two of the most important quality indicators of pc-WLEDs. Through experiments, this article proposes using the scattering enhancement particles (SEPs) such as CaF<sub>2 </sub>and SiO<sub>2 </sub>with yellow phosphor Y<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>:Ce<sup>3+</sup> in pc-WLEDs configuration. The pc-WLEDs model is created by using the LightTools program and set at 8500 K correlated color temperature, while the experimental results yielded from this simulation will be verified by Mie-scattering theory. The information from this article reveals the scattering coefficients of SEPs at 455 nm and 595 nm wavelengths. Moreover, it is confirmed that the employment of CaF<sub>2 </sub>is effective in promoting the color but may damage the luminous efficiency if the concentration is too high while the SEP material, SiO<sub>2</sub>, exhibits high luminous efficiency at all concentration.</span>

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Tsai, Chun-Chin. « Color Rendering Index Thermal Stability Improvement of Glass-Based Phosphor-Converted White Light-Emitting Diodes for Solid-State Lighting ». International Journal of Photoenergy 2014 (2014) : 1–6. http://dx.doi.org/10.1155/2014/407239.

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High color rendering index performance has been required for phosphor-converted warm-white light-emitting diodes (PC-WWLEDs) in lighting industry. The characteristics of low-temperature fabricated phosphor (yellow: Ce3+:YAG, green: Tb3+:YAG, and red: CaAlClSiN3:Eu2+) doped glass were presented for applications to high color rendering index warm-white-light-emitting diodes. Color coordinates (x, y) = (0.36, 0.29), quantum yield (QY) = 55.6%, color rending index (CRI) = 85.3, and correlated color temperature (CCT) = 3923 K were characterized. Glass-based PC-WWLEDs was found able to maintain good thermal stability for long-time high-temperature operation. QY decay, CRI remenance, and chromaticity shift were also analyzed for glass- and silicone-based high-power PC-WLEDs by thermal aging at 150°C and 250°C for industrial test standard’s aging time 1008 hours. Better than the silicone’s, thermal stability of glass-based PC-WLEDs has been improved. The resulted high color rendering index (CRI) glass phosphor potentially can be used as a phosphor layer for high-performance and low-cost PC-WLEDs used in next-generation indoor solid-state lighting applications.

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Peng, Gang, Zhijie Zhu, Yu Tian, Yu-long Tong, Ting-Ting Cui, Cai-Feng Wang et Su Chen. « Dendrimer-induced colloids towards robust fluorescent photonic crystal films and high performance WLEDs ». Journal of Materials Chemistry C 6, n^o 30 (2018) : 8187–93. http://dx.doi.org/10.1039/c8tc02484g.

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Xing, Gongcheng, Yuxin Feng, Zhiyu Gao, Mengxuan Tao, Hongquan Wang, Yi Wei, Maxim S. Molokeev et Guogang Li. « A novel red-emitting La2CaHfO6:Mn4+ phosphor based on double perovskite structure for pc-WLEDs lighting ». CrystEngComm 21, n^o 23 (2019) : 3605–12. http://dx.doi.org/10.1039/c9ce00556k.

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Lin, Yuan-Chih, Paul Erhart et Maths Karlsson. « Vibrationally induced color shift tuning of photoluminescence in Ce3+-doped garnet phosphors ». Journal of Materials Chemistry C 7, n^o 41 (2019) : 12926–34. http://dx.doi.org/10.1039/c9tc01244c.

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Hong, Feng, Ge Pang, Lijuan Diao, Zhendong Fu, Guixia Liu, Xiangting Dong, Wensheng Yu et Jinxian Wang. « Local structure modulation of Mn4+-doped Na2Si1−yGeyF6 red phosphors for enhancement of emission intensity, moisture resistance, thermal stability and application in warm pc-WLEDs ». Dalton Transactions 49, n^o 39 (2020) : 13805–17. http://dx.doi.org/10.1039/d0dt02935a.

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Santra, Angshuman, Nisnat Chakraborty, Karamjyoti Panigrahi, Kalyan K. Chattopadhyay et Uttam Kumar Ghorai. « SrTiO3 : Sm3+, Na+-codoped orange-emitting nanophosphor for pc-WLEDs ». Journal of Materials Science : Materials in Electronics 33, n^o 11 (9 octobre 2021) : 1–15. http://dx.doi.org/10.1007/s10854-021-06876-5.

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Shih, Bao-Jen, Shih-Chen Chiou, Yu-Hua Hsieh, Ching-Cherng Sun, Tsung-Hsun Yang, Szu-Yu Chen et Te-Yuan Chung. « Study of temperature distributions in pc-WLEDs with different phosphor packages ». Optics Express 23, n^o 26 (23 décembre 2015) : 33861. http://dx.doi.org/10.1364/oe.23.033861.

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Wei, Yi, Hui Jia, Hui Xiao, Meng Meng Shang, Chun Che Lin, Chaochin Su, Ting-Shan Chan, Guo Gang Li et Jun Lin. « Emitting-tunable Eu(2+/3+)-doped Ca(8−x)La(2+x) (PO4)6−x(SiO4)xO2 apatite phosphor for n-UV WLEDs with high-color-rendering ». RSC Advances 7, n^o 4 (2017) : 1899–904. http://dx.doi.org/10.1039/c6ra26869b.

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A colorful phosphor [Ca_8−xLa_2+x(PO₄)_6−x(SiO₄)_xO₂:Eu²⁺/Eu³⁺] was designed by cosubstituting [Ca²⁺–P⁵⁺] for [La³⁺–Si⁴⁺] for pc-WLEDs with a high CRI.

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Wenting, Cai. « Effects of Fe2+ on Moisture Resistance of Fluoride Red Phosphors ». E3S Web of Conferences 271 (2021) : 04008. http://dx.doi.org/10.1051/e3sconf/202127104008.

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Nowadays, K2SiF6:Mn4+ has been made extensive use of in technologies available, applied to LCD (Liquid crystal display) and pc-WLEDs (Phosphor-converted white light-emitting diodes). Nevertheless, there are still some significant problems needing solved, one of which is the poor moisture resistance. To expand its application in optical devices, this paper proposes a green and simple strategy on the basis of Fe2+, which effectively achieves a reduction of the reaction between water and luminescence center.

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Cai, Wenting. « Highly Stable Mn4+-Activated Red-Emitting Fluoride Phosphors and Enhanced moisture stability for White LEDs ». E3S Web of Conferences 271 (2021) : 04016. http://dx.doi.org/10.1051/e3sconf/202127104016.

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As a highly productive narrow-band emission red phosphor, K2SiF6:Mn4+ has towardly application market in pc-WLEDs (Phosphor-converted white light-emitting diodes) and LCD (Liquid crystal display). However, the poor moisture resistance property is recognized impediment for generalizing its wider commercialization. Herein, we adopt a simply green and convenient strategy based on Fe2+, which is committed to decreasing the reaction between luminescence center and water. The K2SiF6:Mn4+ as expected exhibits highly efficient red emission upon excitation.

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Chung, Te-yuan, Shih-Chen Chiou, Yu-Yu Chang, Ching-Cherng Sun, Tsung-Hsun Yang et Szu-Yu Chen. « Study of Temperature Distribution Within pc-WLEDs Using the Remote-Dome Phosphor Package ». IEEE Photonics Journal 7, n^o 2 (avril 2015) : 1–11. http://dx.doi.org/10.1109/jphot.2015.2412934.

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Li, Guogang, Ying Tian, Yun Zhao et Jun Lin. « Recent progress in luminescence tuning of Ce3+and Eu2+-activated phosphors for pc-WLEDs ». Chemical Society Reviews 44, n^o 23 (2015) : 8688–713. http://dx.doi.org/10.1039/c4cs00446a.

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Tong, Ye, YiHang Chen, SunYueZi Chen, RongFei Wei, LiPing Chen et Hai Guo. « Luminescent properties of Na2GdMg2(VO4)3:Eu3+ red phosphors for NUV excited pc-WLEDs ». Ceramics International 47, n^o 9 (mai 2021) : 12320–26. http://dx.doi.org/10.1016/j.ceramint.2021.01.083.

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Hooda, Anju, S. P. Khatkar, Sushma Devi et V. B. Taxak. « Structural and spectroscopic analysis of green glowing down-converted BYO:Er3+ nanophosphors for pc-WLEDs ». Ceramics International 47, n^o 18 (septembre 2021) : 25602–13. http://dx.doi.org/10.1016/j.ceramint.2021.05.286.

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Zheng, Weibing, Haibo Rao, Ting Li, Qinghao Meng, Jun Peng et Zhiqi Wu. « Optimized Self-Adaptive Phosphor-Coating Structure of pc-WLEDs by Double Conformal Coating Technology ». IEEE Transactions on Components, Packaging and Manufacturing Technology 9, n^o 6 (juin 2019) : 1200–1202. http://dx.doi.org/10.1109/tcpmt.2019.2912025.

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Zhao, Ming, Zhiguo Xia, Xiaoxiao Huang, Lixin Ning, Romain Gautier, Maxim S. Molokeev, Yayun Zhou et al. « Li substituent tuning of LED phosphors with enhanced efficiency, tunable photoluminescence, and improved thermal stability ». Science Advances 5, n^o 1 (janvier 2019) : eaav0363. http://dx.doi.org/10.1126/sciadv.aav0363.

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Solid-state phosphor-converted white light-emitting diodes (pc-WLEDs) are currently revolutionizing the lighting industry. To advance the technology, phosphors with high efficiency, tunable photoluminescence, and high thermal stability are required. Here, we demonstrate that a simple lithium incorporation in NaAlSiO4:Eu system enables the simultaneous fulfillment of the three criteria. The Li substitution at Al sites beside Na sites in NaAlSiO4:Eu leads to an enhanced emission intensity/efficiency owing to an effective Eu3+to Eu2+reduction, an emission color tuning from yellow to green by tuning the occupation of different Eu sites, and an improvement of luminescence thermal stability as a result of the interplay with Li-related defects. A pc-WLED using the Li-codoped NaAlSiO4:Eu as a green component exhibits improved performance. The phosphors with multiple activator sites can facilitate the positive synergistic effect on luminescence properties.

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Yu, Bin, Yuchan Li, Yunjian Wang et Lei Geng. « Double-site Eu3+ occupation in the langbeinite-type phosphate phosphor toward adjustable emission for pc-WLEDs ». Journal of Alloys and Compounds 874 (septembre 2021) : 159862. http://dx.doi.org/10.1016/j.jallcom.2021.159862.

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Yang, Chenguang, Yangai Liu, Haojun Yu, Yukun Liu, Xiaoya Bu, Juyu Yang, Cian Xie et Jian Chen. « Introducing cation disorder to enhance thermal stability in LuY3(BO3)4 : Eu3+ phosphors for pc-WLEDs ». Optical Materials 129 (juillet 2022) : 112501. http://dx.doi.org/10.1016/j.optmat.2022.112501.

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Zhang, Xinyi, et Jian-Feng Sun. « Intense blue emission of perovskite-type fluoride phosphor Cs4Mg3CaF12 : Eu2+ as a promising pc-WLEDs material ». Journal of Alloys and Compounds 835 (septembre 2020) : 155225. http://dx.doi.org/10.1016/j.jallcom.2020.155225.

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Sehrawat, Priyanka, Avni Khatkar, Anju Hooda, Mukesh Kumar, Rajesh Kumar, R. K. Malik, S. P. Khatkar et V. B. Taxak. « An energy-efficient novel emerald Er3+ doped SrGdAlO4 nanophosphor for PC WLEDs excitable by NUV light ». Ceramics International 45, n^o 18 (décembre 2019) : 24104–14. http://dx.doi.org/10.1016/j.ceramint.2019.08.118.

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Yu, Bin, Yuchan Li, Ruiping Zhang, Hua Li et Yunjian Wang. « A novel thermally stable eulytite-type NaBaBi2(PO4)3:Eu3+ red-emitting phosphor for pc-WLEDs ». Journal of Alloys and Compounds 852 (janvier 2021) : 157020. http://dx.doi.org/10.1016/j.jallcom.2020.157020.

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Sheoran, Monika, Priyanka Sehrawat, Mukesh Kumar, Neelam Kumari, V. B. Taxak, S. P. Khatkar et R. K. Malik. « Synthesis and crystal structural analysis of a green light-emitting Ba5Zn4Y8O21:Er3+ nanophosphor for PC-WLEDs applications ». Journal of Materials Science : Materials in Electronics 32, n^o 9 (18 avril 2021) : 11683–94. http://dx.doi.org/10.1007/s10854-021-05787-9.

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Shakhno, Anna, Anton Markovskyi, Tetiana Zorenko, Sandra Witkiewicz-Łukaszek, Yevheniya Vlasyuk, Andres Osvet, Jack Elia, Christoph J. Brabec, Miroslaw Batentschuk et Yuriy Zorenko. « Micropowder Ca2YMgScSi3O12:Ce Silicate Garnet as an Efficient Light Converter for White LEDs ». Materials 15, n^o 11 (1 juin 2022) : 3942. http://dx.doi.org/10.3390/ma15113942.

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This work is dedicated to the crystallization and luminescent properties of a prospective Ca2YMgScSi3O12:Ce (CYMSSG:Ce) micropowder (MP) phosphor converter (pc) for a white light–emitting LED (WLED). The set of MP samples was obtained by conventional solid-phase synthesis using different amounts of B2O3 flux in the 1–5 mole percentage range. The luminescent properties of the CYMSSG:Ce MPs were investigated at different Ce3+ concentrations in the 1–5 atomic percentage range. The formation of several Ce3+ multicenters in the CYMSSG:Ce MPs was detected in the emission and excitation spectra as well as the decay kinetics of the Ce3+ luminescence. The creation of the Ce3+ multicenters in CYMSSG:Ce garnet results from: (i) the substitution by the Ce3+ ions of the heterovalent Ca2+ and Y3+ cations in the dodecahedral position of the garnet host; (ii) the inhomogeneous local environment of the Ce3+ ions when the octahedral positions of the garnet are replaced by heterovalent Mg2+ and Sc3+ cations and the tetrahedral positions are replaced by Si4+ cations. The presence of Ce3+ multicenters significantly enhances the Ce3+ emission band in the red range in comparison with conventional YAG:Ce phosphor. Prototypes of the WLEDs were also created in this work by using CYMSSG:Ce MP films as phosphor converters. Furthermore, the dependence of the photoconversion properties on the layer thickness of the CYMSSG:Ce MP was studied as well. The changes in the MP layer thickness enable the tuning of the white light thons from cold white/daylight to neutral white. The obtained results are encouraging and can be useful for the development of a novel generation of pcs for WLEDs.

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Sheoran, Monika, Priyanka Sehrawat, Neelam Kumari, Mukesh Kumar et R. K. Malik. « Fabrication and photoluminescent features of cool-white light emanating Dy3+ doped Ba5Zn4Gd8O21 nanophosphors for near UV-excited pc-WLEDs ». Chemical Physics Impact 4 (juin 2022) : 100063. http://dx.doi.org/10.1016/j.chphi.2022.100063.

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Le, Phan Xuan, et Le Hung Tien. « Triple-layer remote phosphor structure : a selection of the higher color quality and lumen efficiency for WLEDs ». Bulletin of Electrical Engineering and Informatics 10, n^o 4 (1 août 2021) : 1960–67. http://dx.doi.org/10.11591/eei.v10i4.3084.

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To enhance color quality of glass-based phosphor-converted white light-emitting diodes (pc-WLEDs) with multi-layer remote phosphor layer structures, two phosphors, green CdS:In and red ZnS:Te,Mn, are integrated into the glass matrix and applied to the dual-layer and triple-layer WLED packages. The attained results were examined with Mie-scattering theory and Lambert-Beer law. The dual-layer showed significant enhancement in color rendering index (CRI), in the range of approximate 80-90. Meanwhile, CRI in the triple-layer was lower and stayed around 66. In terms of color quality scale (CQS), a more overall color evaluating index, triple-layer structure helps the glass-based WLED achieve higher value than the dual-layer. The triple-layer is also beneficial to the luminous efficacy, according to the experimented results. Thus, the triple-layer structure can be used to strengthen the benefit of the glass matrix used in WLED products.

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Sakthivel, Thangavel, G. Annadurai, R. Vijayakumar et Xiaoyong Huang. « Synthesis, luminescence properties and thermal stability of Eu3+-activated Na2Y2B2O7 red phosphors excited by near-UV light for pc-WLEDs ». Journal of Luminescence 205 (janvier 2019) : 129–35. http://dx.doi.org/10.1016/j.jlumin.2018.09.008.

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Sehrawat, Priyanka, Avni Khatkar, Sushma Devi, Anju Hooda, Sonika Singh, R. K. Malik, S. P. Khatkar et V. B. Taxak. « An effective emission of characteristic cool white light from Dy3+ doped perovskite type SrLa2Al2O7 nanophosphors in single-phase pc WLEDs ». Chemical Physics Letters 737 (décembre 2019) : 136842. http://dx.doi.org/10.1016/j.cplett.2019.136842.

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Nguyen, Quang-Khoi, et Thi-Hanh-Thu Vu. « An Efficient Method for Simulating the Temperature Distribution in Regions Containing YAG:Ce3+ Luminescence Composites of White LED ». Journal of Composites Science 7, n^o 7 (22 juillet 2023) : 301. http://dx.doi.org/10.3390/jcs7070301.

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A thermal model was built to estimate the temperature distribution in the hemispherical packaging volume of a white LED at a steady state. Inherent heat sources appeared in the white LED when its power was measured. A simplified 3D to 2D space process that improves the model and solves the heat diffusion equation in a simpler and faster manner is presented. The finite element method was employed using MATLAB software (version R2017b) to identify the temperature distribution. The model was applied for different values of injection current, including 50 mA, 200 mA, 350 mA, and 500 mA. The influence of the injection current and thermal conductivity difference on the temperature distribution of the encapsulant, blue LED die, and substrate region was clearly observed. The results indicate that white light packaging technology should locate phosphor far from the LED die, that the thermal conductivity of the silicone–phosphor region should be improved, that heat should be dissipated for pc-WLEDs when using a high operating power, and that the injection current should be kept as moderate as possible.

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Le, Phan Xuan, Tran Thanh Trang, Nguyen Doan Quoc Anh, Hsiao-Yi Lee et Le Van Tho. « Comparison between SEPs of CaCO₃ and TiO₂ in phosphor layer for better color uniformity and stable luminous flux of WLEDs with 7,000 K ». Materials Science-Poland 40, n^o 1 (1 mars 2022) : 1–8. http://dx.doi.org/10.2478/msp-2022-0008.

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Abstract CaCO3 and TiO2 are proposed in this study as particles for scattering enhancement (SEPs) of phosphor-converted white light-emitting diodes (pc-WLEDs). The use of these two SEPs for scattering improvement enables boosting of the color homogeneity of the WLED devices. Each SEP is mixed with YAG:Ce3+ and silicone composition to examine their optical influences and performances on the high-power WLED packages with 7,000 K color temperature (CT). Miescattering theory is applied to calculate and investigate the scattering elements – scattering coefficients, anisotropic scattering, the reduced scattering, and scattering amplitudes – at the wavelengths of 450 nm and 550 nm. The results exhibit that TiO2 and CaCO3 considerably promote higher color uniformity and color-deviated reduction, respectively. The obtained results could be primarily attributed to the significant improvement in the scattering properties of the structure. Additionally, the effects of the presented scattering enhancement on luminous efficiency are displayed. The reduction in lumen output is observed to have a close connection with the concentration and particle size of TiO2 and CaCO3, which means that control must be exercised over these factors when utilizing these SEPs for WLED fabrication.

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Tadge, Prachi, et Sudeshna Ray. « Mineral-Inspired Approach Mediated Design, Solution Synthesis, and Characterization and Luminescence Study of Blue Emitting Phosphor BaSc₂Si₃O₁₀:Eu²⁺ ». ECS Transactions 107, n^o 1 (24 avril 2022) : 16409–22. http://dx.doi.org/10.1149/10701.16409ecst.

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A series of new silicate based luminescence materials, Ba1-xEuxSc2Si3O10 (BSS:Eu2+) (x = 0.005, 0.01, 0.02, 0.05, 0.07), which can be efficiently excited by UV light and generates a broadband bright blue emission, with ‘Internal Quantum Efficiency’ 45% have been developed from a water-soluble propylene glycol modified silane (PGMS) based silicon precursor by a systematic solution based bottom up approach. The concept as well as the methodology of using a ‘Mineral Inspired Approach’ emerges as a new blueprint for the strategic design of novel phosphors for phosphor converted white light emitting diode (pc-WLEDs). The detailed crystal structure of monoclinic BSS:Eu2+ was determined from the XRD profile. Steady state photoluminescence measurement as well as the thermal quenching properties of the phosphor has been investigated in detail. The optimum concentration of Eu2+ in this matrix was found to be 2% and the ‘Concentration Quenching’ mechanism was verified to be the dipole-dipole interaction and the critical distance was calculated to be 25.01 Å. A highly efficient broadband blue emission centred at λmax ~ 446 nm shows very low thermal quenching; 71.2% at 150 degrees C with respect to that measured at room temperature. The remarkable thermal stability of the phosphor was attributed to the rigid structural network of the host and weak electron-phonon coupling strength. The interesting photoluminescence properties and robust thermal performance reflect the potential application of this phosphor for UVLED driven solid-state lighting.

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Nguyen Thi, Dieu An, et Phan Xuan Le. « Synthesis and photoluminescence properties in white light-emitting diodes of oxynitride green phosphor Ba3Si6O12N2 ». Indonesian Journal of Electrical Engineering and Computer Science 27, n^o 3 (1 septembre 2022) : 1264. http://dx.doi.org/10.11591/ijeecs.v27.i3.pp1264-1269.

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<span>Utilizing boron-coated Eu<sub>2</sub>O<sub>3</sub>, highly effective Ba<sub>3</sub>Si<sub>6</sub>O<sub>12</sub>N<sub>2</sub> green-emitting phosphors were made using a gas reduction nitridation technique under flowing NH<sub>3</sub> gas. We found that the synthesized phosphor is a pure phase of Ba<sub>3</sub>Si<sub>6</sub>O<sub>12</sub>N<sub>2</sub> based on X-ray diffraction patterns. By modifying an alumina boat crystallized, the Ba<sub>3</sub>Si<sub>6</sub>O<sub>12</sub>N<sub>2</sub> green-emitting phosphors from the result were considerably better and had higher emission intensity. Under stimulation at 405 nm, the radiation spectra revealed a typical wide green radiation band attributable to the 4f<sup>6</sup>5d → 4f<sup>7</sup> electronic transfer of Eu<sup>2+</sup> ions. Generally, the green-emitting Ba<sub>3</sub>Si<sub>6</sub>O<sub>12</sub>N<sub>2</sub> phosphors that were created by that method with boron-coated Eu<sub>2</sub>O<sub>3</sub> is a potential phosphor-transformed diodes which emit white illumination white light emitting diodes(pc-WLEDs') element.</span>

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Morozov, Vladimir, Katrien Meert, Philippe Smet, Dirk Poelman, Artem Abakumov et Joke Hadermann. « Incommensurate modulated structures and luminescence in scheelites ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C177. http://dx.doi.org/10.1107/s2053273314098222.

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Scheelite (CaWO4) related compounds (A',A'')n[(B',B'')O4]m with B', B''=W and/or Mo are promising new materials for red phosphors in pc-WLEDs (phosphor-converted white-light-emitting-diode) and solid-state lasers. Scheelites can be prepared with a large concentration of vacancies in the A sublattice, giving compositions characterized by a (A'+A''):(B'O4+B''O4) ratio different from 1:1. The creation of cation vacancies in the scheelite-type framework and the ordering of A cations and vacancies are a new factor in controlling the scheelite-type structure and properties. Very often the substitution of Ca2+ by M+ and R3+ (R3+ = rare earth elements) in the scheelite-type structure leads to switching the structure from 3D to (3+n)D (n = 1,2) regime. The creation and ordering of A-cation vacancies and the effect of cation substitutions in the scheelite-type framework are investigated as a factor controlling the scheelite-type structure and luminescent properties of CaGd2(1-x)Eu2x(MoO4)4(1-y)(WO4)4y (0≤x≤1, 0≤y≤1) solid solutions. Within this series all complex molybdenum oxides have (3+2)D incommensurately modulated structures with superspace group I41/a(α,β,0)00(-β,α,0)00, while the structures of all tungstates are (3+1)D incommensurately modulated with superspace group I2/b(αβ0)00. In both cases the modulation arises due to cation-vacancy ordering at the A site. The replacement of the smaller Gd3+ by the larger Eu3+ at the A-sublattice does not affect the nature of the incommensurate modulation, but an increasing replacement of Mo6+ by W6+ switches the modulation from (3+2)D to (3+1)D regime. Acknowledgement. This research was supported by FWO (project G039211N, Flanders Research Foundation) and Russian Foundation for Basic Research (Grants 11-03-01164, and 12-03-00124).

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Phuong Loan, Nguyen Thi, et Nguyen Doan Quoc Anh. « Utilizing CaCO3, CaF2, SiO2, and TiO2 particles to enhance color homogeneity and luminous flux of WLEDs ». International Journal of Electrical and Computer Engineering (IJECE) 10, n^o 5 (1 octobre 2020) : 5175. http://dx.doi.org/10.11591/ijece.v10i5.pp5175-5182.

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The chromatic homogeneity and luminous efficiency are two crucial elements for determining a high-quality phosphor-converted LEDs (pc-LEDs). Thus, this paper provides essential information in choosing the particles to enhance lighting properties of high performance pc-LEDs. Scattering enhancement particles (SEP) such as CaCO3, CaF2, SiO2, and TiO2, are combined with yellow phosphor Y3Al5O12:Ce3+ and applied to the lighting devices. Initially, optical simulations are carried out with the support of LightTools program. Next, the Mie-theory is applied to calculate and confirm the results. The calculation subjects are SEPs scattering properties within the band 455 -595 nm. The scattering results of TiO2 suggest it is the optimal choice for pc-LEDs color quality in comparison to the other SEPs; however, it causes the luminous flux to decrease significantly along with the increase in its concentration. Besides, with the addition of SiO2 grains, we can accomplish higher lumen output at all particle sizes. Meanwhile, the application of 30% CaCO3 can decrease the CCT deviation by 620 K making CaCO3 the potential particle to be selected for chromatic quality and light output enhancement of pc-LEDs.

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Oh, Ji Hye, Yun Jae Eo, Hee Chang Yoon, Young-Duk Huh et Young Rag Do. « Evaluation of new color metrics : guidelines for developing narrow-band red phosphors for WLEDs ». Journal of Materials Chemistry C 4, n^o 36 (2016) : 8326–48. http://dx.doi.org/10.1039/c6tc02387h.

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In this review, we summarize the recent findings on novel narrow-band red phosphors, the improved color and visual energy properties of these phosphors, and their ability to improve the optical properties of corresponding warm white pc-WLED lightings.

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Wang, Xuejiao, Xiaowen Feng, Maxim Molokeev, Huiling Zheng, Qiushi Wang, Chunyan Xu et Ji-Guang Li. « Broadband green to broadband deep red modulation of Bi3+ luminescence in Lu2WO6 by Gd3+ doping and application in high color rendering index white LED and Near-infrared LED ». Dalton Transactions, 2023. http://dx.doi.org/10.1039/d2dt03751c.

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Phosphors that exhibit tunable broadband emissions are highly desired in multi-functional LEDs, including pc-WLEDs and pc-NIR LEDs. In this work, broadband emissions were obtained and modulated in the unexpectedly wide...

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Huang, Jinmei, Pengfei Jiang, Zien Cheng, Jie Qin, Rihong Cong et Tao Yang. « Equivalent chemical substitution in double-double perovskite-type ALaLiTeO6:Mn4+ (A = Ba2+, Sr2+, Ca2+) phosphors enabling wide range crystal field strength regulation and efficient far-red emission ». Dalton Transactions, 2023. http://dx.doi.org/10.1039/d2dt03845e.

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Mn4+-activated phosphors have shown wide perspective applications in phosphor-converted white light-emitting diodes (pc-WLEDs) and pc-LEDs used in illumination and indoor plant cultivation, respectively. Recently, double perovskites A2B′B″O6 with tunable crystal...

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Wang, Rongrong, Guihua Li et Gemei Cai. « Thermal-stability Synergy Improvement of Sm3+ and Eu3+ in Ca3.6In3.6(PO4)6 : the Effect of Local Symmetry ». Journal of Materials Chemistry C, 2023. http://dx.doi.org/10.1039/d2tc05406j.

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The thermal stability of phosphors especially for the red component is a major factor restricting the quality improvement for PC-WLEDs. Many researchers have invested numerous time and effort in developing...

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Iwaki, Masato, Mizuho Onodera, Kazuyoshi Uematsu, Kenji Toda et Mineo Sato. « Near Ultraviolet Excitable Cyan-Green Phosphors of Ba6La2Al3ScO15:Ce3+ and Ba6La2Al3ScO15:Ce3+,Tb3+ : Investigations on Crystal Structure, Site Assignment of Ce3+ and Tb3+ Ions, and Energy Transfer Process from Ce3+ to Tb3+ ». Dalton Transactions, 2023. http://dx.doi.org/10.1039/d3dt00383c.

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An energy transfer from Ce3+ to Tb3+ is feasible in energy transition processes for development of optical devices, especially phosphor-converted white LEDs (pc-wLEDs). Most of energy transfer phosphors co-doped with...

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Zhang, Ziwang, Nan Yang, Zhuo Li, Jun Chen, Pin Chen, Yiqin Xu, Jianxin Shi et Mingmei Wu. « A Multi-centre Activated Single-phase White Light Phosphor with High Efficiency for Near-UV Based WLEDs ». Inorganic Chemistry Frontiers, 2023. http://dx.doi.org/10.1039/d3qi00685a.

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Single-phase white light phosphors for phosphor-converted white light-emitting diodes (pc-WLEDs) have become a hot spot and attracted considerable attention. However, the unsatisfactory luminous efficiency and colour rendering index of this...

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Qin, Jie, Pengfei Jiang, Rihong Cong et Tao Yang. « Exclusive confinement of Bi3+-activators in the triangular prism enabling efficient and thermally stable green emission in tridymite-type phosphor CaBaGa4O8:Bi3+ ». Dalton Transactions, 2023. http://dx.doi.org/10.1039/d3dt01928d.

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Recently, Bi3+-activated phosphors have been extensively studied for perspective applications in phosphor-converted white light-emitting diodes (pc-WLEDs). However, Bi3+ activators usually exhibit a low quantum efficiency and poor thermal stability due...

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Li, Li, Yongbin Hua, Jae Su Yu, Weiguang Ran et Tian Wang. « Modulating A site compositions of europium(III)-doped double-perovskite niobate phosphors for versatile applications ». Inorganic Chemistry Frontiers, 2022. http://dx.doi.org/10.1039/d2qi02044k.

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It is well-known that red-emitting phosphors can significantly improve the lighting and backlight display qualities of phosphor-converted white light-emitting diodes (pc-WLEDs). However, it is still a challenging task to develop...

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Zhao, Kai, Zhihong Ma, Li Yin, Bin Hui, Han Si, Xinlin Tong, Huidong Tang, Peng Cao et Saifang Huang. « Site Preference and Defect Engineering of a Highly Efficient Blue-Emitting Phosphor Sr2SiO4:Ce3+/K+ Toward Thermally Enhanced Luminescence ». Inorganic Chemistry Frontiers, 2023. http://dx.doi.org/10.1039/d3qi00180f.

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Blue-emitting phosphor is one of the trichromatic phosphors essential for the development of near-ultraviolet (nUV) pumped phosphor-converted white light-emitting diodes (pc-WLEDs). Efficiency and thermal stability are two critical factors for...

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Zheng, Xiaozhou, Li Yue, Chang Wang, Pengju Xia, Man Xu et WUBIN DAI. « Structure and Luminescence Properties of Single-Component Melilite Sr₂MgSi₂O₇ : Ce/Tb/Sm for n-UV wLEDs ». Dalton Transactions, 2023. http://dx.doi.org/10.1039/d3dt02331a.

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Phosphor-converted white light-emitting diodes (pc-wLEDs) have been attracted attention all along in solid-state lighting field. Selection and study on suitable single-phase phosphor and packaging mode are currently the main research...

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Duan, Bosong, Ting Wang, Nannan Zhu, Xin An, Qingshan He, Xuanyu Zhu, Haozhe Liu, Wei Feng et Xue Yu. « Li+ Ion Doping Induced Photoluminescence Enhancement and Anti-Thermal Quenching of LaOBr : Eu3+ Phosphor ». ECS Journal of Solid State Science and Technology, 25 janvier 2023. http://dx.doi.org/10.1149/2162-8777/acb612.

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Abstract Thermal quenching (TQ) seriously restricts the practical applications of phosphor-converted white-lighting-emitting diodes (pc-WLEDs), especially for high-power operations. Here, a novel red-emitting phosphor of LaOBr: Eu3+ with layered tetragonal structure is successfully synthesized by a solid-state reaction approach. By additionally Li+ ions doping into LaOBr: Eu3+, the as-obtained phosphors manifest excellent performance with high internal quenching efficiency (58.6%) and anti-thermal quenching performance. It is demonstrated that the structural rigidity of the lattice matrix could be enhanced with the introduction of Li+ ions and then contribute to the suppression of TQ and the improvement of the luminescence efficiency. Furthermore, a fabricated WLED based on the LaOBr: Eu3+, Li+ sample displays a satisfying color rendering index (CRI = 83.1) and correlated color temperature (CCT = 4719K), revealing the great potential of the as-obtained red phosphor for pc-WLEDs.

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Ahn, Yong Nam, Kyu Do Kim, Gopinathan Anoop, Gab Soo Kim et Jae Soo Yoo. « Design of highly efficient phosphor-converted white light-emitting diodes with color rendering indices (R1 − R15) ≥ 95 for artificial lighting ». Scientific Reports 9, n^o 1 (14 novembre 2019). http://dx.doi.org/10.1038/s41598-019-53269-0.

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AbstractPhosphor-converted white light-emitting diodes (pc-WLEDs) are excellent energy-efficient light sources for artificial lighting applications. One goal of artificial lighting is to make objects/images look natural – as they look under the sunlight. The ability of a light source to accurately render the natural color of an object is gauged by the parameter – color rendering index (CRI). A conventional pc-WLED has an average CRI ~ 80, which is very low for accurate color reproduction. To utilize the pc-WLEDs for artificial lighting applications, all the CRI points (R1 – R15) should be above 95. However, there is a trade-off between CRI and luminous efficacy (LER), and it is challenging to increase both CRI and LER. Herein we propose a novel LED package (PKG) design to achieve CRI points ≥95 and efficiency ~100 lm/W by introducing two blue LEDs and a UV LED in combination with green and red phosphors. The silicone encapsulant, the current through the LEDs, and the green/red phosphor ratio were optimized for achieving high CRI and LER. Our re-designed LED PKG will find applications in stadium lighting as well as for ultra-high-definition television production where high CRI points are required for the artificial light source.

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Dang, Peipei, Guogang Li, Xiaohan Yun, Qianqian Zhang, Dongjie Liu, Hongzhou Lian, Mengmeng Shang et Jun Lin. « Thermally stable and highly efficient red-emitting Eu3+-doped Cs3GdGe3O9 phosphors for WLEDs : non-concentration quenching and negative thermal expansion ». Light : Science & ; Applications 10, n^o 1 (1 février 2021). http://dx.doi.org/10.1038/s41377-021-00469-x.

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AbstractRed phosphor materials play a key role in improving the lighting and backlit display quality of phosphor-converted white light-emitting diodes (pc-WLEDs). However, the development of a red phosphor with simultaneous high efficiency, excellent thermal stability and high colour purity is still a challenge. In this work, unique non-concentration quenching in solid-solution Cs3Gd1 − xGe3O9:xEu3+ (CGGO:xEu3+) (x = 0.1–1.0) phosphors is successfully developed to achieve a highly efficient red-emitting Cs3EuGe3O9 (CEGO) phosphor. Under the optimal 464 nm blue light excitation, CEGO shows a strong red emission at 611 nm with a high colour purity of 95.07% and a high internal quantum efficiency of 94%. Impressively, this red-emitting CEGO phosphor exhibits a better thermal stability at higher temperatures (175–250 °C, >90%) than typical red K2SiF6:Mn4+ and Y2O3:Eu3+ phosphors, and has a remarkable volumetric negative thermal expansion (coefficient of thermal expansion, α = −5.06 × 10−5/°C, 25–250 °C). By employing this red CEGO phosphor, a fabricated pc-WLED emits warm white light with colour coordinates (0.364, 0.383), a high colour rendering index (CRI = 89.7), and a low colour coordinate temperature (CCT = 4508 K). These results indicate that this highly efficient red-emitting phosphor has great potential as a red component for pc-WLEDs, opening a new perspective for developing new phosphor materials.

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Baghel, Sanjay Kumar, Nameeta Brahme, D. P. Bisen, Yugbodh Patle, Neekita Shah et Sukhraj Nureti. « Structural and Luminescence Properties of a Novel Srzrsi2o7:Eu3+ Phosphor Potential for Pc-Wleds Application ». SSRN Electronic Journal, 2022. http://dx.doi.org/10.2139/ssrn.4004695.

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