scholarly journals Enhance the chromatic uniformity and luminous efficiency of WLEDs with triple-layer remote phosphor structures

2020 ◽  
Vol 10 (6) ◽  
pp. 6244
Author(s):  
Nguyen Thi Phuong Loan ◽  
Anh Tuan Le
Keyword(s):  
Layer Structure ◽  
Luminous Flux ◽  
Color Temperature ◽  
Color Quality ◽  
Important Target ◽  
Triple Layer ◽  
Color Uniformity ◽  
Remote Phosphor ◽  
Color Rendering ◽  
Better Than

The angular color uniformity (ACU) with the ability to evaluate chromatic performance of WLED has become an important target to achieve in producing higher-quality WLEDs. This paper studies the ACU enhancing effects of novel triple-phosphor configuration in lighting devices with remote phosphor structure. Moreover, the optical influences of remote phosphor structure with three phosphor layers (TL) on WLEDs properties are calculated and compared to the dual-layer (DL) one for reference. The experiments are applied to devices at 5 distinct correlated color temperature ranging from 5600-8500 K. The results presented that DL structure attains better color rendering index (CRI) than the TL one. Meanwhile, in terms of color quality scales (CQS), TL model shows higher values at all ACCTs, compared to the DL. Moreover, the luminous flux of DL configuration is lower than that of TL structure. In addition, the diversion of color temperature depicts as D-CCT in TL structure is much better than the value in DL structure, especially at high ACCT as 8500 K, which means TL is good for chromatic uniformity of high ACCTs WLEDs. These results proved that the triple-layer structure is superior and more effective to apply for acquiring the enhancement of WLEDs package.

scholarly journals Enhancement of color quality and luminous flux for remote-phosphor LEDs with red-emitting CaMgSi2O6:Eu2+,Mn2+

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Guo-Feng Luo ◽  
Nguyen Thi Phuong Loan ◽  
Le Van Tho ◽  
Nguyen Doan Quoc Anh ◽  
Hsiao-Yi Lee
Keyword(s):  
Mie Scattering ◽  
Luminous Flux ◽  
Color Temperature ◽  
Optical Efficiency ◽  
White Leds ◽  
Color Quality ◽  
Quality Scale ◽  
Color Uniformity ◽  
Remote Phosphor ◽  
Color Rendering

AbstractSiO2 particles and red-emitting CaMgSi2O6:Eu2+,Mn2+ phosphor have been added into a yellow phosphor compound YAG:Ce3+ to enhance the optical efficiency of white light LEDs whose average correlated color temperature (CCT) is in the range of 5600 K ÷ 8500 K. It was observed that altering CaMgSi2O6:Eu2+,Mn2+ concentration from 2 % to 30 % while maintaining 5 % of the SiO2 strongly influenced the color rendering index (CRI), color quality scale (CQS), and lumen efficiency of the compound. Besides, through the application of Monte Carlo simulation and Mie-scattering theory, it was possible to improve the optical properties by CaMgSi2O6:Eu2+,Mn2+ and SiO2 addition. The results provided a practical approach to achieve higher luminous efficiency and better color uniformity in remote-phosphor white LEDs (RP-WLEDs).

scholarly journals Selecting a Suitable Remote Phosphor Configuration for Improving Color Quality of White Led

2019 ◽  
Vol 3 (4) ◽  
pp. 503
Author(s):  
Hsiao-Yi Lee ◽  
Phan Xuan Le ◽  
Doan Quoc Anh Nguyen
Keyword(s):  
Color Temperature ◽  
Research Results ◽  
White Leds ◽  
Creative Commons ◽  
Color Quality ◽  
Triple Layer ◽  
Color Uniformity ◽  
Remote Phosphor ◽  
Color Rendering

When compared with two conformal phosphor and in-cup phosphor structures, the remote phosphor structure has higher luminescent performance. However, it is difficult to control the color quality of the remote phosphor structure, so it has become a research target in recent years. So far, there are two remote phosphor structures used to improve color quality including dual-layer phosphor configuration and triple-layer phosphor configuration. This study suggests using those two configurations to make multi-chip white LEDs (WLEDs) that can achieve adequate values in color rendering index (CRI), color quality scale (CQS), luminous efficacy (LE) and color uniformity. WLEDs with a color temperature of 5600 K are applied. Research results show that the triple-layer phosphor configuration is superior in CRI, CQS, LE. Besides, the color deviation decreases significantly, meaning that the color homogeneity increases with the triple-layer phosphor configuration. This can be demonstrated by analyzing the scattering characteristics of phosphor classes through Mie theory, thus making the research results more reliable and valuable for producing quality WLEDs. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

scholarly journals Triple-layer remote phosphor structure: a novel option for the enhancement of WLEDs’ color quality and luminous flux

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
My Hanh Nguyen Thi ◽  
Phung Ton That ◽  
Nguyen Doan Quoc Anh ◽  
Tran Thanh Trang
Keyword(s):  
Performance Enhancement ◽  
Light Output ◽  
Luminous Flux ◽  
White Leds ◽  
Color Quality ◽  
Quality Scale ◽  
Color Uniformity ◽  
Remote Phosphor ◽  
Research Findings ◽  
Color Rendering

Abstract The remote phosphor as a lighting structure has outstanding luminous efficiency compared to other options, such as conformal or in-cup. However, the lack of uniformity in distributed color has prevented remote phosphor from wider development. The answer to the chromatic performance enhancement that has been suggested by numerous researchers is the multi-layer configuration with two or three different types of chromatic phosphor. The research purpose is to select the best configuration for multi-chip white LEDs (WLEDs) to achieve optimal results in color quality scale (CQS), color rendering index (CRI), light output and color homogeneity. WLEDs mentioned in this paper have two distinct color temperatures, 6600 K and 7700 K. Experimental results show that the remote phosphor structure with three phosphor layers is superior in terms of color rendering, chromatic performance, and emitted light. The deviation of correlated color measured in this structure is also low, which means that the color uniformity is greatly enhanced in this multi-layer lighting structure. This result can be demonstrated by analyzing the scattering characteristics of the phosphoric layers using the Mie theory. The research findings have proven the effectiveness of the multi-phosphor configuration and can serve as a guideline to fabricate WLEDs with better performance.

scholarly journals Improving color quality and luminous flux of white LED utilizing triple-layer remote phosphor structure

2020 ◽  
Vol 10 (5) ◽  
pp. 5168
Author(s):  
Nguyen Thi Phuong Loan ◽  
Nguyen Doan Quoc Anh
Keyword(s):  
Light Quality ◽  
Mie Theory ◽  
Luminous Flux ◽  
Luminous Efficiency ◽  
White Led ◽  
Color Quality ◽  
Triple Layer ◽  
Quality Scale ◽  
Color Uniformity ◽  
Color Rendering

In this manuscript, we presented a research that enhance the performance of WLED using the multi-phosphor configuration. The phosphor layers in the research are separated from each other to achieved better luminous efficiency, however, it makes controlling color light quality more complex. Another issue is finding out the whether two layers of phosphor or three layers of phosphor is better in improving color quality. The research addressed this issue by analyzing the optical aspects of the respective WLEDs that employ these structure. The studied aspects are quality indicators such as luminous efficacy (LE), and color uniformity, color rendering index (CRI), color quality scale (CQS). The results of the experiments in this research, which come from the employment of WLEDs with 2 color temperatures 5600 K and 8500, suggest that WLED with three phosphor layers is better in CRI, CQS, LE. This type of phosphor structure also limits the color deviation significantly, thus, improves the color uniformity. This results is verifies with Mie theory, therefore, can be applied as reference or guideline for production of better WLEDs

scholarly journals Improving the optical efficiency of white light-emitting diodes based on phosphor-in-glass by a dual-layer remote phosphorus structure with the application of LiLaO2:Eu3+ and CaSO4:Ce3+, Mn2+

2021 ◽  
Vol 10 (4) ◽  
pp. 1838-1845
Author(s):  
Phan Xuan Le ◽  
Le Tien
Keyword(s):  
White Light ◽  
Mie Scattering ◽  
Luminous Flux ◽  
Color Temperature ◽  
Phosphor Layer ◽  
Green Phosphor ◽  
Optical Efficiency ◽  
Color Quality ◽  
Color Uniformity ◽  
Remote Phosphor

While the remote phosphor structure is not an appropriate solution for WLED color uniformity, it is more advantageous for the luminous output of WLED than the conformal phosphor or in-cup phosphor structure. Acknowledging the ability of the remote phosphor structure, many studies have been carried out to surmount the color quality disadvantage of this structure. A dual-layer remote phosphor configuration is proposed in this research paper to acquire better color quality for WLEDs through heightening the color rendering index (CRI) and the color quality scale (CQS). The color temperature of the WLED packages this study is 8500 K. By inserting a layer of green CaSO4:Ce3+,Mn2+ or red LiLaO2:Eu3+ phosphor on the yellow YAG:Ce3+ phosphor layer, the phosphor structure configuration can be constructed. Then, to get the best color quality, the concentration of added phosphor LiLaO2:Eu3+ would be changed. The findings showed the rise of CRI and CQS along with the LiLaO2:Eu3+, which implies the influence of LiLaO2:Eu3+ to the growth of red light components within WLEDs packages. The greater the concentration of LiLaO2:Eu3+ is, the more the CRI and CQS increase. Meanwhile, the luminous flux gains from the green phosphor CaSO4:Ce3+,Mn2+. Nevertheless, the luminous flux and color quality would decrease if the concentrations of both red LiLaO2:Eu3+ and green CaSO4:Ce3+,Mn2+ phosphors reach a certain corresponding level. Centered on the Mie-scattering theory and the law of Lambert-Beer, this result is illustrated. The findings in this research are vital references for manufacturing WLEDs with higher white light performance.

scholarly journals The Impacts of Red-emitting Mg2TiO4:Mn4+ Phosphor on Color Quality of Dual-layer Remote Phosphor Configuration

2019 ◽  
Vol 3 (3) ◽  
pp. 464
Author(s):  
Hsiao-Yi Lee ◽  
Phan Xuan Le ◽  
Doan Quoc Anh Nguyen
Keyword(s):  
Red Light ◽  
Mie Scattering ◽  
Conformal Structure ◽  
Luminous Flux ◽  
Color Temperature ◽  
Phosphor Layer ◽  
Creative Commons ◽  
Color Quality ◽  
Remote Phosphor ◽  
Color Rendering

In terms of luminous flux, the remote phosphor structure is better than conformal structure or in-cup phosphor structure, however, this structure often has inferior color quality compared to the others. As a result, many studies have been conducted to nd a solution to the drawback mentioned above. In this research, we are after the same goal using WLEDs structure with color temperature of 5600 K and come to the conclusion that dual-layer phosphor structure can improve the color rendering index (CRI) and the color quality scale (CQS). The concept of the research is to place red phosphor layer Mg2TiO4:Mn4+ on a yellow phosphor layer YAG:Ce3+ and locate the concentration of Mg2TiO4:Mn4+ that allows the color quality to reach the highest value. The result shows that Mg2TiO4:Mn4+ benets CRI and CQS, more specifically, the addition of Mg2TiO4:Mn4+ in WLEDs boosts the red light component, thus, enhancing CRI and CQS. However, it is demonstrated through the application of Mie-scattering theory and Lambert-Beer law that when the concentration of Mg2TiO4:Mn4+ exceed the limit, it can harm the luminous flux of WLEDs. The result of this research is a valuable contribution to improving the techniques of manufacturing better WLEDs with higher white light quality.  This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

scholarly journals Novel lighting properties of white LEDs with two-layered remote phosphor package using red-emitting α-SrO·3B2O3:Sm2+ phosphor

2017 ◽  
Vol 35 (3) ◽  
pp. 618-625
Author(s):  
Tran Hoang Quang Minh ◽  
Nguyen Huu Khanh Nhan ◽  
Nguyen Doan Quoc Anh ◽  
Hsiao-Yi Lee
Keyword(s):  
Lower Layer ◽  
Luminous Flux ◽  
Color Temperature ◽  
Phosphor Layer ◽  
Light Emitting ◽  
White Leds ◽  
Color Uniformity ◽  
Remote Phosphor ◽  
White Light Emitting Diodes ◽  
Color Rendering

AbstractThis paper investigates a method for improving the lighting performance of white light-emitting diodes (WLEDs), packaged using two separating remote phosphor layers, yellow-emitting YAG:Ce phosphor layer and red-emitting α-SrO·3B2O3:Sm2+ phosphor layer. The thicknesses of these two layers are 800 μm and 200 μm, respectively. Both of them have been examined at average correlated color temperatures (CCT) of 7700 K and 8500 K. For this two-layer model, the concentration of red phosphor has been varied from 2 % to 30 % in the upper layer, while in the lower layer the yellow phosphor concentration was kept at 15 %. It was found interesting that the lighting properties, such as color rendering index (CRI) and luminous flux, are enhanced significantly, while the color uniformity is maintained at a level relatively close to the level in one-layer configuration (measured at the same correlated color temperature). Besides, the transmitted and reflected light of each phosphor layer have been revised by combining Kubelka-Munk and Mie-Lorenz theories. Through the analysis, it is demonstrated that the packaging configuration of two-layered remote phosphor that contains red-emitting α-SrO·3B2O3:Sm2+ phosphor particles provides a practical solution to general WLEDs lighting.

scholarly journals Triple-layer remote phosphor structure: a selection of the higher color quality and lumen efficiency for WLEDs

2021 ◽  
Vol 10 (4) ◽  
pp. 1960-1967
Author(s):  
Phan Xuan Le ◽  
Le Hung Tien
Keyword(s):  
Glass Matrix ◽  
Layer Structure ◽  
Mie Scattering ◽  
Phosphor Layer ◽  
Light Emitting ◽  
Color Quality ◽  
Triple Layer ◽  
Remote Phosphor ◽  
White Light Emitting Diodes ◽  
Color Rendering

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.

scholarly journals Selection of Remote Phosphor Led Packages for Improving Luminous Flux

2020 ◽  
Vol 4 (2) ◽  
pp. 118
Author(s):  
Ming Jui Chen ◽  
Hsiao-Yi Lee ◽  
Nguyen Doan Quoc Anh ◽  
Thi Phuong Loan Nguyen ◽  
Van Tho Le
Keyword(s):  
White Light ◽  
Layer Structure ◽  
Luminous Flux ◽  
White Leds ◽  
Creative Commons ◽  
Triple Layer ◽  
Study Results ◽  
Remote Phosphor ◽  
Color Rendering Index ◽  
Color Rendering

In this paper, the first issue presented and analyzed by several experiments is the influence of the distance between phosphor layers in the dual-layer and triple-layer remote package on luminous flux and color rendering property. During the simulation, it was realized that it was possible to create a suitable distance to create higher quality white light-emitting diodes (WLEDs) by adjusting the distance between the phosphor layers. According to the study results, 0.1 mm is the most reasonable distance between two phosphor layers so that the performance of the multi-chip white light LED (MCW LED) can get the best optimal effect. Through a series of experiments, it has been proved that the efficiency of the two-layer structure gives optical properties higher than the three-layer structure related to distance. The highest achievable lumen output is 0.6 mm for the triple-layer structure and 0.1 mm for dual-layer structure. Meanwhile, the color rendering index changes insignificantly when the distance increases. The triple-layer package is not practical for high-power white LEDs due to the high cost and low conversion efficiency. The dual-layer remote phosphor package with a 0.1 mm phosphorus gap is the optimal structure of WLED in improving luminous efficiency and color rendering index.  This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

scholarly journals Increasing Optical Performance of the 7000 K, 8500 K Remote Packaging WLEDs by the Red-emitting α-SrO·3B2O3:Sm2+ Conversion Phosphor

2018 ◽  
Vol 2 (1) ◽  
pp. 55
Author(s):  
Hoang Quang Minh Tran ◽  
Huu Khanh Nhan Nguyen ◽  
Hsiao-Yi Lee
Keyword(s):  
Luminous Flux ◽  
Color Temperature ◽  
Optical Performance ◽  
White Leds ◽  
Creative Commons ◽  
Color Quality ◽  
Quality Scale ◽  
Color Uniformity ◽  
Color Rendering ◽  
Open Access Article

In this paper, by mixing the red-emitting α-SrO·3B2O3:Sm2+ conversion phosphor to yellow-emitting YAG:Ce phosphor compound, an innovative recommendation for increasing optical performance of white LEDs (WLEDs) with remote packaging, which has an average correlated color temperature (CCT) of 700K and 8500K, is proposed and demonstrated. By varying α-SrO·3B2O3:Sm2+ concentration from 2% to 24 %, the obtained results indicated that color uniformity, color rendering index (CRI), color quality scale (CQS), and luminous flux could be improved significantly. The results demonstrated a prospective recommendation for manufacturing remote packaging phosphor WLEDs.  This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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