scholarly journals The Application of Calcium Carbonate CaCO3 and Titania TiO2 for Color Homogeneity and Luminous Flux Enhancement in PC-LEDs

2021 ◽  
Vol 5 (2) ◽  
pp. 75
Author(s):  
Viet Tien Pham ◽  
Ngoc Hung Phan ◽  
Guo-Feng Luo ◽  
Hsiao-Yi Lee ◽  
Doan Quoc Anh Nguyen
Keyword(s):  
Anisotropic Scattering ◽  
Mie Scattering ◽  
Luminous Flux ◽  
Color Temperature ◽  
Optical Simulation ◽  
Development Method ◽  
Scattering Coefficients ◽  
Creative Commons ◽  
Mie Scattering Theory ◽  
Open Access Article

This article studies the development method of pc-LED, a phosphor-converted lighting emitting diode, with scattering enhancement particles (SEPs) at 7000 K correlated color temperature. The pc-LED is an advanced lighting solution that has been applied in many different categories; nonetheless, to keep up with the demands of modern lighting, the pc-LEDs need to enhance the color homogeneity and luminous flux. The detailed experiments on the two SEPs used in the articles are also presented. The experiments include combining each of these SEPs with a yellow phosphor Y3Al5O12:Ce3+ to test their properties and influences on the lighting of pc-LEDs. The scattering coefficients, the anisotropic scattering, the reduced scattering, and the scattering amplitudes at 450 nm and 550 nm are the subjects of SEPs study. The LightTools program is used to create the simulation of pc-LED, the results of the optical simulation will then be verified with the Mie-scattering theory. The findings of the research conclude that TiO2 particles are the best for the growth of color homogeneity while CaCO3 particles are effective in limiting the color deviation in correlated color temperature. Even though the SEPs benefit the lighting performance, their concentration must be managed to be under an acceptable amount to ensure desired results and avoid unwanted damages.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 Applying calcium fluoride and silica particles: A solution to improve color homogeneity of pc-WLEDS

2021 ◽  
Vol 11 (5) ◽  
pp. 3864
Author(s):  
Huu Phuc Dang ◽  
Nguyen Thi Phuong Loan ◽  
Thanh Tung Nguyen ◽  
Sang Dang Ho
Keyword(s):  
Calcium Fluoride ◽  
Scattering Theory ◽  
Mie Scattering ◽  
Luminous Flux ◽  
Luminous Efficiency ◽  
Color Temperature ◽  
Yellow Phosphor ◽  
Scattering Coefficients ◽  
Important Quality ◽  
Mie Scattering Theory

<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>

scholarly journals The effectiveness of MgCeAl11O19:Tb3+ phosphor in enhancing the luminous efficacy and color quality of multi-chip white LEDs

2020 ◽  
Vol 10 (5) ◽  
pp. 4631
Author(s):  
Nguyen Thi Phuong Loan ◽  
Nguyen Doan Quoc Anh
Keyword(s):  
Optical Properties ◽  
Mie Scattering ◽  
Luminous Flux ◽  
Color Temperature ◽  
White Leds ◽  
Color Quality ◽  
Supporting Material ◽  
Mie Scattering Theory ◽  
Led Lights

In this research paper, we introduced yellow-green MgCeAl11O19:Tb3+ asa new phosphor ingredient to adapt to the quality requirements onthe chromatic homogeneity and emitted luminous flux of modern multi-chip white LED lights (MCW-LEDs). The results from experiments and simulation show that employing MgCeAl11O19:Tb3+ phosphor can lead to much better optical properties and therefore is a perfect supporting material to achieve the goals of the research. When the MgCeAl11O19:Tb3+ phosphor is added into the phosphorus composite which already contains YAG: Ce3+ particles, and the silicone glue, it affects the optical properties significantly. In other words, the concentration of this phosphor can determine the efficiency of lumen output and chromatic homogeneity of WLEDs. In specific, as the concentration of MgCeAl11O19:Tb3+ go up, the luminous yield will increase accordingly, though there is an insignificant decrease in CQS. Moreover, if the MgCeAl11O19:Tb3+ concentration reduce a little bit, it is possible to better the correlated color temperature uniformity and lumen efficacy of LED packages. In addition, the Mie scattering theory, Monte Carlo simulation and LightTools 8.3.2 software are employed to analyze and simulate the LED packages’ structure as well as the phosphor compound.

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 Enhanced Luminous Flux of White Led using Flat Dual-layer Remote Phosphor Configuration

2019 ◽  
Vol 3 (2) ◽  
pp. 425
Author(s):  
Doan Quoc Anh Nguyen ◽  
Xuan Le Phan ◽  
Hsiao-Yi Lee
Keyword(s):  
Black Body ◽  
Luminous Flux ◽  
Color Temperature ◽  
White Led ◽  
Absorption Properties ◽  
Phosphor Layer ◽  
Creative Commons ◽  
Remote Phosphor ◽  
The Difference ◽  
Open Access Article

The luminous flux of two different dual-remote phosphor structures concluding flat dual-remote phosphor (FDRP) and concave dual-remote phosphor (CDRP) is compared in this paper. The outcomes demonstrate that the FDRP structure is more lucrative than the CDRP structure. The article additionally clears up that in CDRP structure, the distance between two phosphor layers (d1) and the distance between the phosphor layer with the LED surface (d2) enormously affect the optical properties. Moreover, the difference in d1 and d2 causes a dramatic variance in the scattering and absorption properties of the remote phosphor layer and hence hugely affects WLEDs' illumination ability and chromatic uniformity. In order to limit these problems, the correlated color temperature of WLEDs, which is essentially a gauge of how the chromaticity observed when a "black body" radiator is warmed to a foreordained temperature, should be balanced out at 8500K when d1 and d2 vary, requiring a suitable modification of the YAG:Ce3+ phosphor's concentration. When d1 = d2 = 0, the scattering and assimilation in the remote phosphor layer become lowermost, prompting the most reduced viability in both shading quality and iridescent transition, which is confirmed dependent on the unearthly impacts created when these two separations are not same. Then again, when d1 and d2 get bigger, so does the dispersing surface, and the mixing of the blue beams with yellow beams swings to be increasingly homogeneous. This gives the insignificant different white light yet can't achieve any enhancement for luminous flux. According to the researched results, the luminous flux reaches a peak at 1020 lm when d1 = 0.08 mm or d2 = 0.63 mm whereas the chromatic inhomogeneity hits the lowest point when d1 = 0.64 mm or d2 = 1.35 mm.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.

scholarly journals The Application of Mg2TiO4:Mn4+ and NaYF4:Er3+;Yb3+ and Double Convex Structure in Improving Optical Performance of Phosphor-in-Glass Based White Light-Emitting Diodes

2020 ◽  
Vol 4 (4) ◽  
pp. 218
Author(s):  
Thinh Cong Tran ◽  
Guo-Feng Luo ◽  
Thi Phuong Loan Nguyen ◽  
Van Tho Le ◽  
Doan Quoc Anh Nguyen
Keyword(s):  
Mie Scattering ◽  
Luminous Flux ◽  
Phosphor Layer ◽  
Green Phosphor ◽  
Red Phosphor ◽  
Light Emitting ◽  
Creative Commons ◽  
Color Quality ◽  
Remote Phosphor ◽  
Manufacturing Procedure

Improving lighting performance of WLEDs, especially the color quality, has always been a priority in lighting researches. Recently, the conventional remote phosphor configuration is unable to fulfill the needs of the modern lighting market, particularly the high color expression demand has inspired the search for a novel manufacturing procedure. In this study, based on the results from previous studies, the struggles in enhancing lighting performances are pointed out, and a solution, the dual-layer remote phosphor, is proposed from our conducted experiments. Through experiments with NaYF4:Er3+;Yb3+ and Mg2TiO4:Mn4+ phosphors, the dual-layer phosphor is proven to be effective in improving lighting properties such as color rendering index (CRI) and color quality scale (CQS). The research method involves structuring and experimenting with the phosphor configuration of the yellow phosphor YAG:Ce3+ layer with a green NaYF4:Er3+;Yb3+ or a red Mg2TiO4:Mn4+ phosphor layer whose phosphor concentrations are varied. The results show that the red phosphor Mg2TiO4:Mn4+ particles benefit the CRI and CQS because the values of CRI and CQS increase with red phosphor Mg2TiO4:Mn4+ concentration. On the other hand, the green phosphor NaYF4:Er3+;Yb3+ is inferior in improving CRI and CQS but exhibits better luminous flux. Despite being useful in enhancing lighting performance, the phosphor concentration must be kept below a certain level, which will be mentioned in the article, to prevent damages. These results are verified using Mie scattering theory and Lambert-Beer's law and can be utilized in producing WLEDs with high lighting 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.

A SIMPLE METHOD FOR PREDICTION OF THE REDUCED SCATTERING COEFFICIENT IN TISSUE-SIMULATING PHANTOMS

2010 ◽  
Vol 03 (01) ◽  
pp. 53-59 ◽  
Author(s):  
JIANWEI FU ◽  
GUOTAO QUAN ◽  
HUI GONG
Keyword(s):  
Mie Theory ◽  
Mie Scattering ◽  
Integrating Sphere ◽  
Simple Method ◽  
Scattering Coefficients ◽  
India Ink ◽  
Multiple Wavelengths ◽  
Mie Scattering Theory ◽  
Theory Calculation ◽  
Tissue Simulating Phantoms

This paper proposes a method for predicting the reduced scattering coefficients of tissue-simulating phantoms or the desired amount of scatters for producing phantoms according to Mie scattering theory without measurements with other instruments. The concentration of the scatters TiO 2 particles is determined according to Mie theory calculation and added to transparent host epoxy resin to produce phantoms with different reduced scattering coefficients. Black India Ink is added to alter the absorption coefficients of the phantoms. The reduced scattering coefficients of phantoms are measured with single integrating sphere system. The results show that the measurements are in direct proportion to the concentration of TiO 2 and have identical with Mie theory calculation at multiple wavelengths. The method proposed can accurately determine the concentration of scatters in the phantoms to ensure the phantoms are qualified with desired reduced scattering coefficients at specified wavelength. This investigation should be possible to manufacture the phantom simply in reasonably accurate for evaluation of biomedical optical imaging systems.

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 ZnO Nanoparticles in Bettering The Color Uniformity of Phosphor-Converted White Led Lights

2020 ◽  
Vol 4 (3) ◽  
pp. 173
Author(s):  
Ming-Jui Chen ◽  
Van Tho Le ◽  
Doan Quoc Anh Nguyen ◽  
Thinh Cong Tran
Keyword(s):  
Particle Size ◽  
Mie Scattering ◽  
Phosphor Layer ◽  
Creative Commons ◽  
Color Uniformity ◽  
Theoretical Application ◽  
The One ◽  
The Right ◽  
Led Lights ◽  
Open Access Article

To make further improvements in future WLED generation, bettering color uniformity is an important goal manufacturers desire to accomplish. One of the most common and effective methods to enhance the color homogeneity is the one focusing on improving scattering in phosphor layer which can be achieved by adding ZnO into the phosphor layer. Based on theoretical application of Mie-scattering, we compute and analyze the scattering characteristics of the diffusor particles. From the results, the ZnO particles are proven to have positive influences on the development of lighting quality. Additionally, the article analyzed and presented the effects of ZnO concentration which fluctuates from 2% to 22% on the color homogeneity. Thus, the color uniformity is influenced not only by the particle size but also by the concentration of the added ZnO. Hence, managing the color uniformity of WLEDs means controlling the size and concentration of ZnO. With the concentration of 10% ZnO, the lumen output of LEDs reaches the highest values. Meanwhile, when the concentration and size of ZnO are 14% and 500 nm respectively, ∆CCT is reduced to the lowest value. Based on the manufacturers' requirements, the most appropriate ZnO concentration and particle size can be determined. However, if requirements include both lumen and color uniformity, the right choice is 14% concentration with 500 nm particle size of ZnO. 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 The Impacts of Red-Emitting SrwFxByOz:Eu2+,Sm2+ Phosphor on Color Quality of Dual-Layer Phosphor Geometry

2018 ◽  
Vol 2 (3) ◽  
pp. 208
Author(s):  
Doan Quoc Anh Nguyen
Keyword(s):  
Luminous Flux ◽  
Creative Commons ◽  
Color Quality ◽  
Yellow Phosphorus ◽  
Quality Scale ◽  
Remote Phosphor ◽  
Different Color ◽  
Color Rendering ◽  
Open Access Article

When the features of remote phosphor structure are compared with these of conformal phosphor or in-cup phosphor, it is recognized that it is more outstanding than the rest about luminous flux but the quality of color tends to be worse. Through that we have grasped these disadvantages and find out many studies in order to improve the color of the remote phosphor structure. In this study, we propose a dual-layer remote phosphor structure that could improve the color rendering index (CRI) and color quality scale (CQS) for WLEDs. In this study, three similar WLEDs structures but having different color temperatures including 5600 K, 6600 K and 7700K are applied. The principal idea is putting a red phosphoric layer SrwFxByOz:Eu2+,Sm2+ on the yellow phosphorus layer YAG:Ce3+. The results show that SrwFxByOz:Eu2+,Sm2+  brings great benefits to increasing CRI and CQS. Specifically, the greater the concentration of SrwFxByOz:Eu2+,Sm2+ has, the higher CRI and CQS get. However, the declining trend of luminous flux occurs when the SrwFxByOz:Eu2+,Sm2+ concentration exceeds the level. This can be demonstrated through the results of the study and be explained by the Mie dispersion theory and the Lambert-Beer law. The results of this article are important in making WLEDs of higher color 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.

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