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All Journal TELKOMNIKA (Telecommunication Computing Electronics and Control) Bulletin of Electrical Engineering and Informatics
Le Hung Tien
Van Lang University
Computer Science & IT Electrical & Electronics Engineering

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The application of Ca5B2SiO10:Eu3+ and YAl3B4O12:Ce3+,Mn2+ in dual-layer remote phosphor to enhance lumen output and color quality of WLEDs Phan Xuan Le; Le Hung Tien
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 5: October 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i5.15024

Abstract

This study proposes a dual-layer remote phosphor structure, comprised of a green or a red phosphor layer and a yellow YAG:Ce3+ phosphor layer, to enhance color rendering index (CRI) and color quality scale (CQS) of white light-emitting diodes (WLEDs). The phosphors used in this study are green phosphor YAl3B4O12:Ce3+,Mn2+ and red phosphor Ca5B2SiO10:Eu3+. Besides, the applied WLED structure has the color temperature of 8500 K. The study demonstrates the idea of placing a green phosphor YAl3B4O12:Ce3+,Mn2+ or a red Ca5B2SiO10:Eu3+ phosphor layer on the yellow phosphor YAG:Ce3+ one. After that, the suitable concentration of Ca5B2SiO10:Eu3+ resulting in the highest color quality is determined. The obtained results showed that Ca5B2SiO10:Eu3+ is advantageous to CRI and CQS. Particularly, the values of CRI and CQS increased following the growth of Ca5B2SiO10:Eu3+ concentration, due to the rise in red light components inside WLED’s packages. Meanwhile, the luminous flux is benefited by the added green YAl3B4O12:Ce3+,Mn2+ phosphor. However, there are decreases in lumen output and color quality when the concentrations of Ca5B2SiO10:Eu3+ and YAl3B4O12:Ce3+,Mn2+ rise over the corresponding levels. This result is proved via using Mie-scattering theory and Lambert-Beer's law. In short, the findings of the research paper are valuable references for high-light-quality WLEDs fabrication.
Triple-layer remote phosphor structure: a selection of the higher color quality and lumen efficiency for WLEDs Phan Xuan Le; Le Hung Tien
Bulletin of Electrical Engineering and Informatics Vol 10, No 4: August 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v10i4.3084

Abstract

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.
(Y,Gd)BO3:Eu red phosphor for dual-layer phosphor structure to enhance the optical performance of white light-emitting diodes Phan Xuan Le; Le Hung Tien
Bulletin of Electrical Engineering and Informatics Vol 10, No 4: August 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v10i4.2909

Abstract

Among the structures using for fabricating white light-emitting diodes (WLEDs) such as the conformal coating or in-cup geometries, the remote phosphor structure gives the highest luminous efficacy. However, in terms of color quality, its performance is not as good as the others. The red-light compensation has been reported as the effective solution for enhancing the color quality of WLEDs. Hence, this study adopted the idea and applied to the dual-layer phosphor structure. The phosphor used to boost the red color in light formation is (Y,Gd)BO3:Eu particle. The dual-layer remote phosphor structure was simulated with the red (Y,Gd)BO3:Eu phosphor layer above the original yellow phosphor YAG:Ce3+ one. The WLEDs with different correlated color temperatures of 5600 K, 6600 K and 7700K were experimented. Mie-theory and Lambert-Beer law were applied to examine the results. The growth in color rendering index (CRI) and color quality scale (CQS) with the increase of (Y,Gd)BO3:Eu phosphor concentration was observed. Nevertheless, the lumen efficacy would be degraded if the concentration was over a certain number. The information provided in this article is useful for the development of high-power WLED production with greater color quality.
Co-Authors Phan Xuan Le