The concept of the analysis is to put a CaAl2O4:Mn2+ green phosphor layer on top of the YAG:Ce3+ yellow phosphor layer. After that, find the added CaAl2O4:Mn2+ concentration appropriate for the highest luminous flux (LF) and color homogeneity (CH). In this analysis, five equivalent WLEDs were applied but with distinct color temperatures, including 5600 K - 8500 K. The findings showed that CaAl2O4:Mn2+ brings great benefits to increase not only the luminous flux but also the color homogeneity. Especially, the higher the CaAl2O4:Mn2+ concentration, the more the luminous flux released by WLEDs, owing to the risen content of the light of green in WLEDs. Nevertheless, as the CaAl2O4:Mn2+ concentration raised significantly, a small reduction in the color rendering metric (CRI) and color quality scale (CQS) occurred. This is supported by simulation and calculation according to the theory of Monte Carlo. The paper results are the crucial contribution to the manufacture of WLEDs with better optical performance and color homogeneity of remote phosphor configurations.
Study of red-emitting LaAsO4:Eu3+ phosphor for color rendering index improvem...TELKOMNIKA JOURNAL
The remote phosphor structure is often disadvantageous in color quality but in terms of optics it is more convenient when compared to other phosphor structures such as conformal or in-cup ones. From this disadvantage, there are many studies to improve its chromatic output. In this research paper, we propose a dual-layer remote phosphor geometry for the improvement of white light-emitting diodes (WLEDs) in two parameters: color rendering index (CRI) and color quality scale (CQS). The 7700 K WLEDs are used in this study. The idea of the study is to place a red phosphor layer LaAsO4:Eu3+ on the yellow phosphor YAG: Ce3+, and then find the concentration of LaAsO4:Eu3+ in an appropriate way to achieve the highest color quality. The results showed that LaAsO4:Eu3+ bring great benefits for enhancing CRI and CQS. In particular, the greater the concentration of LaAsO4:Eu3+, the greater the CRI and CQS because the portion of red lights in WLEDs increases. However, the decrease in lumen output occurs when the concentration of LaAsO4:Eu3+ increases excessively. This is proved thanks to Mie-scattering theory and Beer-Lambert law. The results of important articles in WLEDs fabrication have greatly contributed to a higher white light quality.
Improving the optical efficiency of white light-emitting diodes based on phos...journalBEEI
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.
(Y,Gd)BO3:Eu red phosphor for dual-layer phosphor structure to enhance the op...journalBEEI
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.
The options in remote phosphor structure for better white LEDs color qualityTELKOMNIKA JOURNAL
The WLEDs configuration with remote phosphor layers has higher luminescent performance than WLEDs with dispense coating or conformal coating and is applied for many modern devices. However, managing the chromatic performance of lighting structure with remote phosphor materials is a challenging objective that demands more research. This has inspired the usage of multi phosphor configurations with distance in between the layers to improve color quality. The results of this manuscript can support the manufacturers in choosing the optimal configuration for optical performance in LEDs devices with more than one phosphor material. The simulated model used in the experments is 6500 K CCT WLEDs, which results show the triple-layers structure is more favorable in terms of color quality and light output. Besides, a notable reduction occurs in color deviation means that chromatic stability is also enhanced in WLEDs with three phosphor layers. Through experimental results, which were confirmed by the Mie-scattering theory, this research offers valuable approach and details to produce better WLEDs.
Excellent color quality of phosphor converted white light emitting diodes wit...TELKOMNIKA JOURNAL
The remote phosphor structure is disadvantageous in color quality but more convenient in luminous flux when compared to conformal phosphor or in-cup phosphor structure. From this disadvantage, there are many studies to improve the color quality of the remote phosphor structure. This research will propose a dual-layer remote phosphor structure to improve color rendering index (CRI) and color quality scale (CQS) of WLEDs. The WLED package with color temperature of 8500 K is utilized in this study. The idea of the study is to locate a layer of phosphor green Y2O2S:Tb3+ or red ZnS:Sn2+ on the yellow phosphor YAG:Ce3+ film, and then finding the suitable added concentration of ZnS:Sn2+ to match the highest color quality. The results showed that ZnS:Sn2+ brings great benefits to increase CRI and CQS. The greater the ZnS:Sn2+ concentration is, the higher the CRI and CQS become owing to the rise in red light components in WLEDs. Meanwhile, the green Y2O2S:Tb3+ phosphor brings benefits to luminous flux. However, the decrease in luminous flux and color quality occurs when the concentration of ZnS:Sn2+ and Y2O2S:Tb3+ exceeds the corresponding level. This is proved by applying Mie-scattering theory and Lambert-Beer's law. The results of articles are important for WLEDs’ fabrication having higher white light quality.
The application of green YPO4:Ce3+,Tb3+ and red LiLaO2:Eu3+ layers to remote ...TELKOMNIKA JOURNAL
Remote phosphor structure is commonly limited in color quality, but has greater luminous flux when comparing to structures with in-cup or conformal coating. From this dilemma, various researches with advance modifications have been proposed to perfect the chromatic performance of remote structure. In this research, we reach higher color quality by obtaining better values in quality indcators such as color rendering index (CRI) and color quality scale (CQS) with the dual-layer phosphor in our remote white light-emitting diodes (WLEDs). The idea is to ultize WLEDs with 7000 K correlated color temperature (CCT) and create dual-layer configuration with yellow phosphor YAG:Ce3+ under green phosphor YPO4:Ce3+,Tb3+ or red phosphor LiLaO2:Eu3+. After that, we search for suitable concentration of LiLaO2:Eu3+ for addition in order to acquire the finest color quality. The result shows that WLED with LiLaO2:Eu3+ has better CRI and CQS as the higher the concentration of LiLaO2:Eu3+, the larger CRI and CQS due to increased light scattered in WLEDs. Meanwhile, the green phosphor layer YPO4:Ce3+,Tb3+ give advantages to luminous flux. However, the reduction in luminous flux and color quality occurs when the concentration of LiLaO2:Eu3+ and YPO4:Ce3+,Tb3+ over increase. Results are verified by Mie theory and Beer’s Law and can be applied to practical manufacturing of high quality WLEDs.
The usage of dual-layer remote phosphor configurations in enhancing color qua...TELKOMNIKA JOURNAL
Among conformal phosphor structure, in-cup phosphor structure, and remote phosphor structure, while in term of attaining the highest luminous flux, remote phosphor structure is the most ideal one, it seems to be that this structure results in the lowest-quality of color. Therefore, it is necessary in conducting experiments to surmount this disadvantage and make a possibility in enhancing the color quality of WLEDs with remote phosphor structure. In this research, with the ability of advancing the color rendering index (CRI) and color quality (CQS) for WLEDs, a dual-layer remote phosphor structure was considered as a suggestion. The experiments in this study used three kinds of WLEDs with the similar structures but different color temperatures varying at 5600 K, 7000 K, and 8500 K. The objectives of this paper is proposing a solution to obtain the highest color quality by placing a yellow-green emitting SrBaSiO4:Eu2+ phosphor layer or a red-emitting SrwFxByOz:Eu2+,Sm2+ phosphor layer on the YAG:Ce3+ phosphor layer and then choosing the most appropriate value of SrwFxByOz:Eu2+,Sm2+ concentration. The experimental results which are satisfied expectations of researchers indicated that SrwFxByOz:Eu2+,Sm2+ has enforced its role in managing to raise the CRI and CQS. Particularly, the greater concentration of SrwFxByOz:Eu2+,Sm2+ leads to the higher the CRI and CQS, since the red light component in WLEDs increased. Besides, the quality of luminous flux is in a tight connection with the SrBaSiO4:Eu2+ phosphor layer. Whereas, according to the Mie scattering theory and the Lambert-Beer law, if the concentration of SrwFxByOz:Eu2+,Sm2+ and SrBaSiO4:Eu2+ becomes redundant, the luminous flux and color quality will take a deep dive. Briefly, the results from this article has largely contributed to fabricating high-quality WLEDs.
The application of double-layer remote phosphor structures in increasing WLED...IJECEIAES
The remote phosphor structure often has inferior color quality but better luminous flux in than conformal or in-cup configurations. Therefore, numerous researches study remote phosphor structure for methods to enhance it chromatic quality. This study introduces the use of dual-layer remote phosphor structure in WLEDs with identical structure but at different color temperature, 6600 K and 7700 K, to demonstrate their effect on quality indicators. The concept is placing a green phosphor layer (Ce,Tb)MgAl 11 O 19 :Ce:Tb or a red phosphor layer MgSr 3 Si 2 O 8 :Eu on the layer of yellow-emitting phosphor YAG:Ce 3+ and find the suitable concentration of the additional phosphor to create the best color quality. The results showed that the increase of CRI and CQS are affected by MgSr 3 Si 2 O 8 :Eu 2+ ,Mn 2+ , in particular, the higher the concentration of red phosphor gets the better CRI and CQS because the emitted red light in enhanced. The green phosphor layer (Ce,Tb)MgAl 11 O 19 :Ce:Tb, on the other hand, is beneficial for the luminous flux. The concentration of MgSr 3 Si 2 O 8 :Eu 2+ ,Mn 2+ and (Ce,Tb)MgAl 11 O 19 :Ce:Tb, however, need to be adjusted properly to avoid decreasing the luminous flux due to overgrowth. The Mie scattering theory and Beer’s law are the verification tools for these conclusions, which gives them the credibility to be applied in producing better quality WLEDs. 2+ ,Mn 2+
Study of red-emitting LaAsO4:Eu3+ phosphor for color rendering index improvem...TELKOMNIKA JOURNAL
The remote phosphor structure is often disadvantageous in color quality but in terms of optics it is more convenient when compared to other phosphor structures such as conformal or in-cup ones. From this disadvantage, there are many studies to improve its chromatic output. In this research paper, we propose a dual-layer remote phosphor geometry for the improvement of white light-emitting diodes (WLEDs) in two parameters: color rendering index (CRI) and color quality scale (CQS). The 7700 K WLEDs are used in this study. The idea of the study is to place a red phosphor layer LaAsO4:Eu3+ on the yellow phosphor YAG: Ce3+, and then find the concentration of LaAsO4:Eu3+ in an appropriate way to achieve the highest color quality. The results showed that LaAsO4:Eu3+ bring great benefits for enhancing CRI and CQS. In particular, the greater the concentration of LaAsO4:Eu3+, the greater the CRI and CQS because the portion of red lights in WLEDs increases. However, the decrease in lumen output occurs when the concentration of LaAsO4:Eu3+ increases excessively. This is proved thanks to Mie-scattering theory and Beer-Lambert law. The results of important articles in WLEDs fabrication have greatly contributed to a higher white light quality.
Improving the optical efficiency of white light-emitting diodes based on phos...journalBEEI
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.
(Y,Gd)BO3:Eu red phosphor for dual-layer phosphor structure to enhance the op...journalBEEI
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.
The options in remote phosphor structure for better white LEDs color qualityTELKOMNIKA JOURNAL
The WLEDs configuration with remote phosphor layers has higher luminescent performance than WLEDs with dispense coating or conformal coating and is applied for many modern devices. However, managing the chromatic performance of lighting structure with remote phosphor materials is a challenging objective that demands more research. This has inspired the usage of multi phosphor configurations with distance in between the layers to improve color quality. The results of this manuscript can support the manufacturers in choosing the optimal configuration for optical performance in LEDs devices with more than one phosphor material. The simulated model used in the experments is 6500 K CCT WLEDs, which results show the triple-layers structure is more favorable in terms of color quality and light output. Besides, a notable reduction occurs in color deviation means that chromatic stability is also enhanced in WLEDs with three phosphor layers. Through experimental results, which were confirmed by the Mie-scattering theory, this research offers valuable approach and details to produce better WLEDs.
Excellent color quality of phosphor converted white light emitting diodes wit...TELKOMNIKA JOURNAL
The remote phosphor structure is disadvantageous in color quality but more convenient in luminous flux when compared to conformal phosphor or in-cup phosphor structure. From this disadvantage, there are many studies to improve the color quality of the remote phosphor structure. This research will propose a dual-layer remote phosphor structure to improve color rendering index (CRI) and color quality scale (CQS) of WLEDs. The WLED package with color temperature of 8500 K is utilized in this study. The idea of the study is to locate a layer of phosphor green Y2O2S:Tb3+ or red ZnS:Sn2+ on the yellow phosphor YAG:Ce3+ film, and then finding the suitable added concentration of ZnS:Sn2+ to match the highest color quality. The results showed that ZnS:Sn2+ brings great benefits to increase CRI and CQS. The greater the ZnS:Sn2+ concentration is, the higher the CRI and CQS become owing to the rise in red light components in WLEDs. Meanwhile, the green Y2O2S:Tb3+ phosphor brings benefits to luminous flux. However, the decrease in luminous flux and color quality occurs when the concentration of ZnS:Sn2+ and Y2O2S:Tb3+ exceeds the corresponding level. This is proved by applying Mie-scattering theory and Lambert-Beer's law. The results of articles are important for WLEDs’ fabrication having higher white light quality.
The application of green YPO4:Ce3+,Tb3+ and red LiLaO2:Eu3+ layers to remote ...TELKOMNIKA JOURNAL
Remote phosphor structure is commonly limited in color quality, but has greater luminous flux when comparing to structures with in-cup or conformal coating. From this dilemma, various researches with advance modifications have been proposed to perfect the chromatic performance of remote structure. In this research, we reach higher color quality by obtaining better values in quality indcators such as color rendering index (CRI) and color quality scale (CQS) with the dual-layer phosphor in our remote white light-emitting diodes (WLEDs). The idea is to ultize WLEDs with 7000 K correlated color temperature (CCT) and create dual-layer configuration with yellow phosphor YAG:Ce3+ under green phosphor YPO4:Ce3+,Tb3+ or red phosphor LiLaO2:Eu3+. After that, we search for suitable concentration of LiLaO2:Eu3+ for addition in order to acquire the finest color quality. The result shows that WLED with LiLaO2:Eu3+ has better CRI and CQS as the higher the concentration of LiLaO2:Eu3+, the larger CRI and CQS due to increased light scattered in WLEDs. Meanwhile, the green phosphor layer YPO4:Ce3+,Tb3+ give advantages to luminous flux. However, the reduction in luminous flux and color quality occurs when the concentration of LiLaO2:Eu3+ and YPO4:Ce3+,Tb3+ over increase. Results are verified by Mie theory and Beer’s Law and can be applied to practical manufacturing of high quality WLEDs.
The usage of dual-layer remote phosphor configurations in enhancing color qua...TELKOMNIKA JOURNAL
Among conformal phosphor structure, in-cup phosphor structure, and remote phosphor structure, while in term of attaining the highest luminous flux, remote phosphor structure is the most ideal one, it seems to be that this structure results in the lowest-quality of color. Therefore, it is necessary in conducting experiments to surmount this disadvantage and make a possibility in enhancing the color quality of WLEDs with remote phosphor structure. In this research, with the ability of advancing the color rendering index (CRI) and color quality (CQS) for WLEDs, a dual-layer remote phosphor structure was considered as a suggestion. The experiments in this study used three kinds of WLEDs with the similar structures but different color temperatures varying at 5600 K, 7000 K, and 8500 K. The objectives of this paper is proposing a solution to obtain the highest color quality by placing a yellow-green emitting SrBaSiO4:Eu2+ phosphor layer or a red-emitting SrwFxByOz:Eu2+,Sm2+ phosphor layer on the YAG:Ce3+ phosphor layer and then choosing the most appropriate value of SrwFxByOz:Eu2+,Sm2+ concentration. The experimental results which are satisfied expectations of researchers indicated that SrwFxByOz:Eu2+,Sm2+ has enforced its role in managing to raise the CRI and CQS. Particularly, the greater concentration of SrwFxByOz:Eu2+,Sm2+ leads to the higher the CRI and CQS, since the red light component in WLEDs increased. Besides, the quality of luminous flux is in a tight connection with the SrBaSiO4:Eu2+ phosphor layer. Whereas, according to the Mie scattering theory and the Lambert-Beer law, if the concentration of SrwFxByOz:Eu2+,Sm2+ and SrBaSiO4:Eu2+ becomes redundant, the luminous flux and color quality will take a deep dive. Briefly, the results from this article has largely contributed to fabricating high-quality WLEDs.
The application of double-layer remote phosphor structures in increasing WLED...IJECEIAES
The remote phosphor structure often has inferior color quality but better luminous flux in than conformal or in-cup configurations. Therefore, numerous researches study remote phosphor structure for methods to enhance it chromatic quality. This study introduces the use of dual-layer remote phosphor structure in WLEDs with identical structure but at different color temperature, 6600 K and 7700 K, to demonstrate their effect on quality indicators. The concept is placing a green phosphor layer (Ce,Tb)MgAl 11 O 19 :Ce:Tb or a red phosphor layer MgSr 3 Si 2 O 8 :Eu on the layer of yellow-emitting phosphor YAG:Ce 3+ and find the suitable concentration of the additional phosphor to create the best color quality. The results showed that the increase of CRI and CQS are affected by MgSr 3 Si 2 O 8 :Eu 2+ ,Mn 2+ , in particular, the higher the concentration of red phosphor gets the better CRI and CQS because the emitted red light in enhanced. The green phosphor layer (Ce,Tb)MgAl 11 O 19 :Ce:Tb, on the other hand, is beneficial for the luminous flux. The concentration of MgSr 3 Si 2 O 8 :Eu 2+ ,Mn 2+ and (Ce,Tb)MgAl 11 O 19 :Ce:Tb, however, need to be adjusted properly to avoid decreasing the luminous flux due to overgrowth. The Mie scattering theory and Beer’s law are the verification tools for these conclusions, which gives them the credibility to be applied in producing better quality WLEDs. 2+ ,Mn 2+
Green-emitting Gd2O2S:Tb3+ and red-emitting Y3Al5O12:Cr3+ phosphors: a suitab...TELKOMNIKA JOURNAL
This article demonstrates green-emitting phosphor Gd2O2S:Tb3+ and red-emitting phosphor Y3Al5O12:Cr3+ application in the triple-layer phosphor WLED to enhance optical performance. The arrangement of phosphor layers in the WLED is red phosphor Y3Al5O12:Cr3+ on top, green phosphor Gd2O2S:Tb3+ in the middle, and yellow phosphor YAG:Ce3+ at the bottom. The principal to utilize these phosphor materials is the exploitation of additional red light component and green light component from the green and red phosphor to enrich the color rendering index (CRI) and luminous efficacy. The influences of green phosphor and red phosphor are also estimated with a new quality indicator, the color quality index (CQS). The results show red phosphor Y3Al5O12:Cr3+ enable CRI when its concentration increases while green phosphor exhibits a contrast reaction. Regarding the CQS, the optimal red phosphor concentration for CQS is from 10% to 14%, disregard the concentration in green phosphor. The improvement that applying these two phosphor materials brought comes from limiting the light loss from back-scattering and strengthen chromatic performance through addition red and green light components. These findings can support manufacturers in adapting to modern lighting requirements by improving CRI, CQS and particularly luminous efficiency to more than 40%.
The application of (Y,Gd)BO3:Tb3+ and CaGa2S4:Mn2+ phosphors to remote white ...TELKOMNIKA JOURNAL
The remote phosphor structure is superior to the conformal phosphor and the in-cup phosphor in terms of lighting efficiency; however, managing the color quality of the remote phosphor structure has been a nuisance to the manufacturers. To address this problem, many researches were conducted and the results suggested that using dual-layer phosphor structure and triple-layer phosphor structure could improve the color quality in remote phosphor structures. The purpose of this article is to study which one between the two configurations mentioned above allows multi-chip white LEDs (WLEDs) to reach highest indexes in color rendering index (CRI), color quality scale (CQS), luminous flux (LF), and color uniformity. The color temperature of the WLEDs used for the experiments in this article is 8500 K. The result of this research shows that the triple-layer phosphor configuration has higher CRI, CQS, and LE and also able to reduce color deviation resulting in better color uniformity. This conclusion can be verified by analyzing the scattering features of the phosphor layers using the Mie-theory. Being verifiable increases the reliability of the research result and makes it a valuable reference for producing better quality WLEDs.
Y 2 O 3 :Ho 3+ and ZnO:Bi 3+ : a selection for enhancing color quality and ...IJECEIAES
As the luminescence industry develops, the white light light-emitting diode (LED) package with a single chip and a single phosphor although produces good luminous flux but has a poor color rendering index (CRI) can no longer fulfill the requirements of modern lighting applications. Therefore, this research is conducted to response to the urgent demands of improving other lighting qualities of WLED while maintaining high luminous efficiency. To achieve this target, we applied the new WLED package, which contains multi-chips and multi-phosphor layers, and have obtained outstanding results in both CRI and luminous efficacy. Two types of phosphor used in the WLED package are Y 2 O 3 :Ho 3+ and ZnO:Bi 3+ . A color configuration model is also developed to adjust the shading of the white-light LED module. The results of this research show that the triple-layer phosphorhas the best performance when applied in a white-light LED package, which is demonstrated through better color quality, CRI and luminous efficacy. The manufacturers can rely on this research to produce the optimal-quality WLED, or WLED that is appropriate to their quality demands.
Improving optical properties of remote phosphor LED using green Y2O3:Ho3+ and...TELKOMNIKA JOURNAL
The lighting device that employs diodes to create white light (WLEDs) with quantum dots (QDs) and phosphor layers is a promising lighting method that is increasingly used in many fields on account of the remarkable color expressing ability. The QDs film is usually placed apart from the phosphor layer according to the packaging configuration to prevent light loss due to backscattering as well as preserve the consistency of the ligands on the QDs surface. The article also conducted experiments to compare the lighting properties and thermal output of the two packaging orders of QDs and phosphor. The heat discharing ranges were simulated with thermography technology, moreover, other parameters such as light energy emission and PL spectra are acquired to evaluate the efficiency of the packaging order. The results from the practical experiment show that while under 10% wt., the luminous output (LO) of green QDs-on-phosphor structure reaches 1130 lm, higher than the red QDs-on-phosphor structure with 878 lm, and the color rendering value in the configuration with red QDs on phosphor is Ra = 74 are higher than Ra = 68 index of the green QDs-on-phosphor structure. As a result, the QDs-on-phosphor is determined as the better packaging configuration to choose to achieve an overall improvement in lighting efficiency, color rendering index
Improving color rendering index of WLEDs with convex-dual-layer remote phosph...TELKOMNIKA JOURNAL
This document summarizes a study that aimed to improve the color rendering index (CRI) of white-light LEDs (WLEDs) using a dual-layer remote phosphor configuration with red-emitting CaGa2S4:Mn2+ phosphor. The study used a simulation model to analyze different phosphor proportions and densities in a package with two LED chips and dual phosphor layers. The results showed that CRI and color quality scale values increased with higher concentrations of CaGa2S4:Mn2+ phosphor. Specifically, CRI values increased from 2% to 24% concentration of the red phosphor. The study provides a method for customizing WLED modules to achieve high C
Benefits of triple-layer remote phosphor structure in improving color quality...TELKOMNIKA JOURNAL
This document discusses the benefits of using a triple-layer remote phosphor structure to improve the color quality and luminous flux of white LEDs. It compares single-layer, dual-layer, and triple-layer phosphor configurations. The results show that the triple-layer structure is most effective at improving the color rendering index, color quality scale, and luminous efficacy. By separating the phosphor layers into yellow, red, and green, the triple-layer structure better balances the complementary colors and reduces light re-absorption losses compared to other structures. The enhanced optical performance of the triple-layer structure can be explained by Mie scattering theory and how it applies to the phosphor particle distributions in each layer. Overall,
The influences of calcium fluoride and silica particles on improving color ho...TELKOMNIKA JOURNAL
The LEDs lighting device with phosphor ingredient (pcLEDs) is among the most common lighting methods in recent years and evaluated by chromatic uniformity and lighting capacity. Therefore, we introduce the phosphor particles that can improve the scattering efficiency (SEPs) to apply in pcLEDs at 8500 K correlated color temperature (CCT) with the expectation to produce better pcLEDs by enhancing both quantity and quality of emitted light. Combining various materials such as CaF2 and SiO2 with yellow Y3Al5O12:Ce3+ phosphor composition in the pcLEDs simulation created by the LightTools program is the mechanism of this research. The simulated pcLEDs are tested and the results will be verified with Mie-scattering theory. The observation of the simulation leads to the conclusion about the scattering coefficients of SEPs at 455 nm and 595 nm wavelengths. The calculation showed that CaF2 is better for color homogeneity yet suffer from luminous flux deficiency as the concentration gets higher. On the other hand, SiO2 is the scattering enhancement material that can maintain high luminous flux regardless of its concentration.
Ba[Mg2Al2N4]Eu2+ phosphor for enhancing the optical quality of the 6600K CPW-...TELKOMNIKA JOURNAL
Compared with conventional lamps, LED-based light sources have a superior lifetime, efficiency, and reliability, which promise significant reductions in power consumption and pollution from fossil fuel power plants. The main purpose of this paper is proposed and investigated the effect of the concentration of Ba[Mg2Al2N4]Eu2+conversion phosphor on the CCT deviation (D-CCT) and lumen output (LO) of the 6600 K conformal-packaging white LEDs (CPW-LEDs). For this purpose, we used the Light Tools and Mat Lab software to investigate this problem. From the research results, we can state that the concentration of the red phosphor crucially influenced on the optical quality of the 6600 K CPW-LEDs. The D-CCT can be decreased from 4700K to 2500K, and the LO can be increased from 600 lm. to 1200 lm. This research can provide the new recommendation for LEDs industry at this time.
Dual-layer remote phosphor structure: a novel technique to enhance the color ...IJECEIAES
The effects of red light-emitting phosphor CaMgSi2O6:Eu2+,Mn2+ on the optical properties of single-layer remote phosphor structure (SRPS) and dual-layer remote phosphor structure (DRPS) are the focus of this study. The differences in color quality and luminous flux (LF) of white lightemitting diodes (WLEDs) between these two structures are also revealed and demonstrated based on the Mie theory. SRPS consists of one mixed phosphor layer betweenCaMgSi2O6:Eu2+,Mn2+ andYAG:Ce3+particles, while DRPS includes two separated layers: red phosphor layer and yellow phosphor layer. In this work, 5% SiO2 is added into the phosphor layers to increase scattering abilities. Discrepancies in structures greatly affect the optical characteristics of WLEDs. The results showed that the color rendering index (CRI) increased with the concentration in both structures with nearly equal values. Meanwhile, color quality scale (CQS) of DPRS is 74 at ACCTs ranging from 5600K to 8500K, higher than CQS of SRPS which is only 71 at 8500K. In addition, the luminous flux of DRPS is significantly higher than SRPS at 2% -14% of CaMgSi2O6:Eu2+,Mn2+. In summary, DRPS is better for color quality and lumen outputin comparison to SRPS and adding the right amount of red phosphor can enhance CQS and LF.
Excellent luminous flux of WLEDs with flat dual-layer remote phosphor geometryTELKOMNIKA JOURNAL
This paper focuses on the comparison of the luminous flux of two dual-remote phosphor
structures named flat dual-remote phosphor (FDRP) and concave dual-remote phosphor (CDRP). These
two configurations have different luminous flux values due to the disparity in scattering properties in white
LEDs. However, the researched results showed that FDRP structure is more lucrative than the CDRP
structure when it comes to the luminous flux effectiveness. To support the aforementioned idea, this article
also presents the influence of the distance between two phosphor layers (d1) and the distance between
the phosphor layer with the LED surface (d2) on the optical properties of the FDRP structure. Specifically,
the scattering ability and absorption properties of the remote phosphor layer will vary sharply if d1 and d2
are adjusted into different values, which produces an immense impact on the chromatic homogeneity and
illumination capability of WLEDs. Therefore, in order to stabilize the correlated color temperature (CCT) of
WLEDs at 8500 K when there is a modification on d1 and d2, the concentration of YAG: Ce3+ phosphor also
needs to be varied. Accordingly, the scattering process and absorption phenomenon in the remote
phosphor layer will bottom out when d1=d2=0, leading to the worst color quality and luminous flux.
The effect of the spectra generated as these distances are adjusted is obvious evidence for this point. In
other words, the larger the d1 and d2, the larger the scattering surface, and thus the blending of blue and
yellow light rays will become more homogeneous, yielding the smallest white light deflection and
the lowest luminous flux at the same time. The paper's results indicated that the luminous flux will reach a
peak at 1020 lm if d1=0.08 mm or d2=0.63 mm and the chromatic deflection will hit the lowest point as
d1=0.64 mm or d2=1.35 mm. In the end, manufacturers can make their choice for the production of
higher-standard WLEDs based on the general knowledge and helpful information that the article has
provided and analyzed.
SrBaSiO 4 :Eu 2+ phosphor: a novel application for improvingthe luminous flu...IJECEIAES
This paper described in detail the chromatic homogeneity and luminous flux influences in producing better quality white LED devices with various phosphor layers (MCW-LEDs). The method is to let Eu -activated strontium–barium silicate (SrBaSiO 4 :Eu 2+ ) mixed with their phosphor compounding, which results in notable impact on lighting performance. The increase in concentration of yellow-green-emitting SrBaSiO 4 :Eu phosphor also promotes the color performance and lumen output of WLED devices at high correlated color temperature around 8500K. This is the first time this approach is applied and it results can be utilized for better understanding of optical properties interaction with phosphor materials. Although SrBaSiO 4 :Eu 2+ receives many positive responses, we still need to limit it concentration for high SrBaSiO 4 :Eu 2+ concentration is detrimental to CQS. The appropriate choice of concentration and size of SrBaSiO 4 :Eu is the principal factor to decide the performance of MCW-LEDs. 2+ 2+ 2+
The application of green YF3:Er3+,Yb3+ and red MgSr3Si2O8:Eu2+,Mn2+ layers to...TELKOMNIKA JOURNAL
White light-emitting diodes (WLEDs) with quantum dots (QDs) and phosphor have pulled in huge consideration because of their incredible shading rendering capacity. In the bundling procedure, a QDs film and a phosphor silicone layer will in general be isolated for lessening the reabsorption misfortunes and keeping the QDs surface molecules in a good condition. This examination explored the bundling succession of QDs and phosphor layers to the optical and warm exhibitions of WLEDs. The emitted optical power and PL spectra were estimated and dissected, while an infrared warm imager was utilized to reenact and approve tentatively the temperature fields. The results reveal that at 60 mA, WLEDs with green QDs-on-phosphor type accomplished lumen output (LO) of 1578 lm, with shading rendering record (CRI) of Ra = 60, while the red QDs-on-phosphor type WLEDs exhibited lower LO of 1000 lm, with Ra = 82. In addition, the QDs-onphosphor type WLEDs generated less warmth than the other, and as a result, the most noteworthy temperature in this packaged type was lower than the other. Additionally, its temperature contrast can arrive at 12.3°C. Along these lines, regarding bundling arrangement, the QDs-on-phosphor type is an ideal bundling design to better the optical productivity and shading rendering capacity, as well as lower gadget temperature.
Utilizing CaCO 3 , CaF 2 , SiO 2 , and TiO 2 particles to enhance color hom...IJECEIAES
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 CaCO 3 , CaF 2 , SiO 2 , and TiO 2 , are combined with yellow phosphor Y 3 Al 5 O 12 :Ce 3+ 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 TiO 2 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 SiO 2 grains, we can accomplish higher lumen output at all particle sizes. Meanwhile, the application of 30% CaCO 3 can decreas the CCT deviation by 620 K making CaCO 3 the potential particle to be selected for chromatic quality and light output enhancement of pc-LEDs.
Na3Ce(PO4)2:Tb3+ and Na(Mg2–xMnX)LiSi4O10F2:Mn phosphors: a suitable selectio...TELKOMNIKA JOURNAL
This document discusses a triple-layer remote phosphor structure (TRP) to enhance the color quality and luminous flux of white light-emitting diodes (WLEDs). The TRP structure contains three phosphor layers arranged from bottom to top: yellow YAG:Ce3+ phosphor, green Na3Ce(PO4)2:Tb3+ phosphor, and red Na(Mg2–xMnX)LiSi4O10F2:Mn phosphor. Simulation results show that the red phosphor improves color rendering index while the green phosphor improves luminous flux but reduces color rendering index. The color quality scale is maximized when there is a balance between the yellow,
Improving color quality and luminous flux of white LED utilizing triple-layer...IJECEIAES
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 K, 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.
Acquiring higher lumen efficacy and color rendering index with green NaYF4:Er...TELKOMNIKA JOURNAL
Lighting devices that apply diodes to create white light-emitting diodes (WLEDs) can achieve remarkable results in color quality, especially those containing quantum dots (QDs) and phosphor. The technique to create an appropriate package is providing spaces between the QDs and phosphor components which helps decrease the ratio of the reabsorption losses and keeps the QDs surface ligands constant. The research aims to perfect the constructing method of remote phosphor configuration containing quantum dots and phosphor materials that based on lighting properties and temperature feature of WLEDs. The infrared thermography is the tool to measure and analyze total emitted light and emission ranges of the device. This device is also used in temperature simulation and experimental verification. At the given mA of 60, the WLEDs structure with green QDs layer above the phosphor layer results in 996 lm luminous flux (LF), and Ra = 57 in color rendering ability. Meanwhile, luminous flux of WLEDs with red QDs-on-phosphor structure is 632, and Ra = 70. Furthermore, comparing with the green QDs-on-phosphor type, the red QDs-on-phosphor type emitted less LF. However, the red QDs-on-phosphor type can be the most effective package design to achieve color rendering ability.
Comparison of calcium carbonate and titania particles on improving color homo...TELKOMNIKA JOURNAL
1) The document compares the effects of adding calcium carbonate (CaCO3) and titania (TiO2) particles to yellow phosphor in phosphor-converted LEDs (pc-LEDs) to improve color uniformity and luminous flux.
2) Simulation results show that pc-LEDs with 30% CaCO3 concentration have a 620K lower correlated color temperature deviation compared to no additional particles, indicating better color uniformity. In contrast, increasing TiO2 concentration sharply reduces luminous flux.
3) CaCO3 particles are recommended for achieving both higher color homogeneity and lumen output in pc-LEDs due to their scattering properties being more equal between blue and yellow light wavelengths.
LaSiO 3 Cl:Ce 3+ ,Tb 3+ and Mg 2 TiO 4 :Mn 4+ : quantum dot phosphors for im...IJECEIAES
In this research, we focus on the solutions to enhance the lighting properties as well as the heat regulation of the white light-emitting diodes (WLEDs) with conventional phosphor and quantum dots (QDs). Although receiving lots of attention for being an innovative lighting solution with good color rendering index, the potentials of WLEDs conjugated with quantum dots (QDS), especially the QDs-phosphor mixed nanocomposites ones, are restrained due to the lacking performance in the aspects mentioned above. The crucial requirement to produce better WLEDs is finding solutions that improve the lacking aspects, therefore, through observing previous studies and applying advanced technique, this research suggest an effective and unique packaging configuration, in which the nanocomposites QDs-phosphor layer is set horizontally to the WLED. This novel packaging configuration allow WLED performance in terms of lighting and heating to reach it peaks. This is the first time four different types of WLEDs, singlelayer phosphor, dual-layer remote phosphor with yellow-red and yellow-green, and triple-layer phosphor, were simulated, utilized and compared in one study to decide the best WLED configuration. The results show that the triple-layer phosphor configurations improve the color rendering ability and lumen output better than the other configurations.
Enhancing the CRI and lumen output for the 6600 K WLED with convex-dual-layer...IJECEIAES
The traditional white LED product established with a single chip and a single phosphor results in a low color rendering index (CRI). The upgrade of LED package is comprised of two chips and one phosphor material and gives the higher CRI while keeping high luminous efficiency. Based on previous findings, the research paper performs the application of the two chips and two phosphors to enhance the color tunability of LEDs with different amounts and intensities of the two employed phosphors. Additionally, a color design model is built to serve the purpose of bettering the color fine-tuning of the white-light LED module. The maximum value of the difference between the measured CIE 1931 color coordinates and that of the simulated model is approximately 0.0063 around the 6600 K correlated color temperature (CCT). From the results, this study offers a quick approach to achieve the color fine tuning of a white-light LED module with a high CRI and luminous efficiency.
Effect of morphology on the photoelectrochemical performance of nanostructure...Pawan Kumar
This document discusses the effect of morphology on the photoelectrochemical performance of nanostructured Cu2O photocathodes. It summarizes that:
1) Different deposition methods including electroreduction, anodization, thermal oxidation, and chemical oxidation were used to deposit planar and 1D nanostructured Cu2O thin films on copper foil with varying morphologies.
2) Mesoscopic and planar Cu2O morphologies exhibited large differences in carrier density and charge transfer resistance, but these differences did not strongly influence their photoelectrochemical performance.
3) Planar Cu2O deposited via electroreduction provided the highest photocurrent density of 5.0 mA cm−2 at 0 V vs RHE,
Application of dual-layer phosphor geometries for enhancing the optical prope...TELKOMNIKA JOURNAL
This article compares the lumen output of two packages of two-remote phosphor (RP). The first package is flat dual-remote phosphor (FDRPS). The second package is concave dual-remote phosphor (CDRP). The dispersion qualities of the white-light-emitting diode are different as a result of their different cover designs, leading to a disparity between the FDRPS and CDRPS configurations. The results of the study show that the FDRPS package yields a lumen output superior to that of the CDRPS package. In the article, we can also see how the space among the phosphor films (𝑑1) and the space among the phosphor film and the light emitting diodes (LED) outer side (𝑑2) might affect the light characteristics in the CDRPS model. As the indicated distances shift, the characteristics of dispersion and absorptivity in the distant phosphor film will shift as well. Such an occurrence can have an impact on chromatic uniformity as well as optical performance in white light emitting diodes (WLEDs). If we modify the and values, it is necessary to change the phosphor YAG:Ce3+ concentration in the WLEDs to keep the correlated color temperature at 8500 K.
Research on advancing chromatic reproduction and luminosity of a WLED using t...TELKOMNIKA JOURNAL
In this study, the use of triple-sheet phosphor arrangement (TRP) in performing significant improvements to both color quality and luminous flux of white light emitting diode (WLEDs) is introduced. The phosphor layer of CaLaB3O7:Ce3+,Mn2+ is to accomplish green-spectra enhancement for the boost of luminous efficacy (LE), while MgB2O4:Mn2+ red phosphor layer is for red-spectra enhancement to better color rendering index (CRI) of WLEDs. The changes in these two phosphors’ concentrations present considerable effects on the yellow phosphor YAG:Ce3+ concentration, the color quality scale (CQS), CRI, and LE. Findings display the decrease of YAG:Ce3+ concentration accompanying the increase of red and green phosphor concentrations, for the stabilized average correlated color temperatures (ACCTs) between 6000 and 8500 K. Results also reveal that greater content of MgB2O4:Mn2+ leads to greater CRI value. Meanwhile using the increasing CaLaB3O7:Ce3+,Mn2+ concentration, the CRI lowers considerably. CQS, on the other hand, can increase with CaLaB3O7:Ce3+,Mn2+ concentration from 10% to 14%. Especially, given the enhancement for the CRI as well as CQS, LE value will surge to more than 40% due to the reduction of scattering light and the addition of green light. The outcome of the study is a priceless reference for light emitting diode (LED) producers.
Green-emitting Gd2O2S:Tb3+ and red-emitting Y3Al5O12:Cr3+ phosphors: a suitab...TELKOMNIKA JOURNAL
This article demonstrates green-emitting phosphor Gd2O2S:Tb3+ and red-emitting phosphor Y3Al5O12:Cr3+ application in the triple-layer phosphor WLED to enhance optical performance. The arrangement of phosphor layers in the WLED is red phosphor Y3Al5O12:Cr3+ on top, green phosphor Gd2O2S:Tb3+ in the middle, and yellow phosphor YAG:Ce3+ at the bottom. The principal to utilize these phosphor materials is the exploitation of additional red light component and green light component from the green and red phosphor to enrich the color rendering index (CRI) and luminous efficacy. The influences of green phosphor and red phosphor are also estimated with a new quality indicator, the color quality index (CQS). The results show red phosphor Y3Al5O12:Cr3+ enable CRI when its concentration increases while green phosphor exhibits a contrast reaction. Regarding the CQS, the optimal red phosphor concentration for CQS is from 10% to 14%, disregard the concentration in green phosphor. The improvement that applying these two phosphor materials brought comes from limiting the light loss from back-scattering and strengthen chromatic performance through addition red and green light components. These findings can support manufacturers in adapting to modern lighting requirements by improving CRI, CQS and particularly luminous efficiency to more than 40%.
The application of (Y,Gd)BO3:Tb3+ and CaGa2S4:Mn2+ phosphors to remote white ...TELKOMNIKA JOURNAL
The remote phosphor structure is superior to the conformal phosphor and the in-cup phosphor in terms of lighting efficiency; however, managing the color quality of the remote phosphor structure has been a nuisance to the manufacturers. To address this problem, many researches were conducted and the results suggested that using dual-layer phosphor structure and triple-layer phosphor structure could improve the color quality in remote phosphor structures. The purpose of this article is to study which one between the two configurations mentioned above allows multi-chip white LEDs (WLEDs) to reach highest indexes in color rendering index (CRI), color quality scale (CQS), luminous flux (LF), and color uniformity. The color temperature of the WLEDs used for the experiments in this article is 8500 K. The result of this research shows that the triple-layer phosphor configuration has higher CRI, CQS, and LE and also able to reduce color deviation resulting in better color uniformity. This conclusion can be verified by analyzing the scattering features of the phosphor layers using the Mie-theory. Being verifiable increases the reliability of the research result and makes it a valuable reference for producing better quality WLEDs.
Y 2 O 3 :Ho 3+ and ZnO:Bi 3+ : a selection for enhancing color quality and ...IJECEIAES
As the luminescence industry develops, the white light light-emitting diode (LED) package with a single chip and a single phosphor although produces good luminous flux but has a poor color rendering index (CRI) can no longer fulfill the requirements of modern lighting applications. Therefore, this research is conducted to response to the urgent demands of improving other lighting qualities of WLED while maintaining high luminous efficiency. To achieve this target, we applied the new WLED package, which contains multi-chips and multi-phosphor layers, and have obtained outstanding results in both CRI and luminous efficacy. Two types of phosphor used in the WLED package are Y 2 O 3 :Ho 3+ and ZnO:Bi 3+ . A color configuration model is also developed to adjust the shading of the white-light LED module. The results of this research show that the triple-layer phosphorhas the best performance when applied in a white-light LED package, which is demonstrated through better color quality, CRI and luminous efficacy. The manufacturers can rely on this research to produce the optimal-quality WLED, or WLED that is appropriate to their quality demands.
Improving optical properties of remote phosphor LED using green Y2O3:Ho3+ and...TELKOMNIKA JOURNAL
The lighting device that employs diodes to create white light (WLEDs) with quantum dots (QDs) and phosphor layers is a promising lighting method that is increasingly used in many fields on account of the remarkable color expressing ability. The QDs film is usually placed apart from the phosphor layer according to the packaging configuration to prevent light loss due to backscattering as well as preserve the consistency of the ligands on the QDs surface. The article also conducted experiments to compare the lighting properties and thermal output of the two packaging orders of QDs and phosphor. The heat discharing ranges were simulated with thermography technology, moreover, other parameters such as light energy emission and PL spectra are acquired to evaluate the efficiency of the packaging order. The results from the practical experiment show that while under 10% wt., the luminous output (LO) of green QDs-on-phosphor structure reaches 1130 lm, higher than the red QDs-on-phosphor structure with 878 lm, and the color rendering value in the configuration with red QDs on phosphor is Ra = 74 are higher than Ra = 68 index of the green QDs-on-phosphor structure. As a result, the QDs-on-phosphor is determined as the better packaging configuration to choose to achieve an overall improvement in lighting efficiency, color rendering index
Improving color rendering index of WLEDs with convex-dual-layer remote phosph...TELKOMNIKA JOURNAL
This document summarizes a study that aimed to improve the color rendering index (CRI) of white-light LEDs (WLEDs) using a dual-layer remote phosphor configuration with red-emitting CaGa2S4:Mn2+ phosphor. The study used a simulation model to analyze different phosphor proportions and densities in a package with two LED chips and dual phosphor layers. The results showed that CRI and color quality scale values increased with higher concentrations of CaGa2S4:Mn2+ phosphor. Specifically, CRI values increased from 2% to 24% concentration of the red phosphor. The study provides a method for customizing WLED modules to achieve high C
Benefits of triple-layer remote phosphor structure in improving color quality...TELKOMNIKA JOURNAL
This document discusses the benefits of using a triple-layer remote phosphor structure to improve the color quality and luminous flux of white LEDs. It compares single-layer, dual-layer, and triple-layer phosphor configurations. The results show that the triple-layer structure is most effective at improving the color rendering index, color quality scale, and luminous efficacy. By separating the phosphor layers into yellow, red, and green, the triple-layer structure better balances the complementary colors and reduces light re-absorption losses compared to other structures. The enhanced optical performance of the triple-layer structure can be explained by Mie scattering theory and how it applies to the phosphor particle distributions in each layer. Overall,
The influences of calcium fluoride and silica particles on improving color ho...TELKOMNIKA JOURNAL
The LEDs lighting device with phosphor ingredient (pcLEDs) is among the most common lighting methods in recent years and evaluated by chromatic uniformity and lighting capacity. Therefore, we introduce the phosphor particles that can improve the scattering efficiency (SEPs) to apply in pcLEDs at 8500 K correlated color temperature (CCT) with the expectation to produce better pcLEDs by enhancing both quantity and quality of emitted light. Combining various materials such as CaF2 and SiO2 with yellow Y3Al5O12:Ce3+ phosphor composition in the pcLEDs simulation created by the LightTools program is the mechanism of this research. The simulated pcLEDs are tested and the results will be verified with Mie-scattering theory. The observation of the simulation leads to the conclusion about the scattering coefficients of SEPs at 455 nm and 595 nm wavelengths. The calculation showed that CaF2 is better for color homogeneity yet suffer from luminous flux deficiency as the concentration gets higher. On the other hand, SiO2 is the scattering enhancement material that can maintain high luminous flux regardless of its concentration.
Ba[Mg2Al2N4]Eu2+ phosphor for enhancing the optical quality of the 6600K CPW-...TELKOMNIKA JOURNAL
Compared with conventional lamps, LED-based light sources have a superior lifetime, efficiency, and reliability, which promise significant reductions in power consumption and pollution from fossil fuel power plants. The main purpose of this paper is proposed and investigated the effect of the concentration of Ba[Mg2Al2N4]Eu2+conversion phosphor on the CCT deviation (D-CCT) and lumen output (LO) of the 6600 K conformal-packaging white LEDs (CPW-LEDs). For this purpose, we used the Light Tools and Mat Lab software to investigate this problem. From the research results, we can state that the concentration of the red phosphor crucially influenced on the optical quality of the 6600 K CPW-LEDs. The D-CCT can be decreased from 4700K to 2500K, and the LO can be increased from 600 lm. to 1200 lm. This research can provide the new recommendation for LEDs industry at this time.
Dual-layer remote phosphor structure: a novel technique to enhance the color ...IJECEIAES
The effects of red light-emitting phosphor CaMgSi2O6:Eu2+,Mn2+ on the optical properties of single-layer remote phosphor structure (SRPS) and dual-layer remote phosphor structure (DRPS) are the focus of this study. The differences in color quality and luminous flux (LF) of white lightemitting diodes (WLEDs) between these two structures are also revealed and demonstrated based on the Mie theory. SRPS consists of one mixed phosphor layer betweenCaMgSi2O6:Eu2+,Mn2+ andYAG:Ce3+particles, while DRPS includes two separated layers: red phosphor layer and yellow phosphor layer. In this work, 5% SiO2 is added into the phosphor layers to increase scattering abilities. Discrepancies in structures greatly affect the optical characteristics of WLEDs. The results showed that the color rendering index (CRI) increased with the concentration in both structures with nearly equal values. Meanwhile, color quality scale (CQS) of DPRS is 74 at ACCTs ranging from 5600K to 8500K, higher than CQS of SRPS which is only 71 at 8500K. In addition, the luminous flux of DRPS is significantly higher than SRPS at 2% -14% of CaMgSi2O6:Eu2+,Mn2+. In summary, DRPS is better for color quality and lumen outputin comparison to SRPS and adding the right amount of red phosphor can enhance CQS and LF.
Excellent luminous flux of WLEDs with flat dual-layer remote phosphor geometryTELKOMNIKA JOURNAL
This paper focuses on the comparison of the luminous flux of two dual-remote phosphor
structures named flat dual-remote phosphor (FDRP) and concave dual-remote phosphor (CDRP). These
two configurations have different luminous flux values due to the disparity in scattering properties in white
LEDs. However, the researched results showed that FDRP structure is more lucrative than the CDRP
structure when it comes to the luminous flux effectiveness. To support the aforementioned idea, this article
also presents the influence of the distance between two phosphor layers (d1) and the distance between
the phosphor layer with the LED surface (d2) on the optical properties of the FDRP structure. Specifically,
the scattering ability and absorption properties of the remote phosphor layer will vary sharply if d1 and d2
are adjusted into different values, which produces an immense impact on the chromatic homogeneity and
illumination capability of WLEDs. Therefore, in order to stabilize the correlated color temperature (CCT) of
WLEDs at 8500 K when there is a modification on d1 and d2, the concentration of YAG: Ce3+ phosphor also
needs to be varied. Accordingly, the scattering process and absorption phenomenon in the remote
phosphor layer will bottom out when d1=d2=0, leading to the worst color quality and luminous flux.
The effect of the spectra generated as these distances are adjusted is obvious evidence for this point. In
other words, the larger the d1 and d2, the larger the scattering surface, and thus the blending of blue and
yellow light rays will become more homogeneous, yielding the smallest white light deflection and
the lowest luminous flux at the same time. The paper's results indicated that the luminous flux will reach a
peak at 1020 lm if d1=0.08 mm or d2=0.63 mm and the chromatic deflection will hit the lowest point as
d1=0.64 mm or d2=1.35 mm. In the end, manufacturers can make their choice for the production of
higher-standard WLEDs based on the general knowledge and helpful information that the article has
provided and analyzed.
SrBaSiO 4 :Eu 2+ phosphor: a novel application for improvingthe luminous flu...IJECEIAES
This paper described in detail the chromatic homogeneity and luminous flux influences in producing better quality white LED devices with various phosphor layers (MCW-LEDs). The method is to let Eu -activated strontium–barium silicate (SrBaSiO 4 :Eu 2+ ) mixed with their phosphor compounding, which results in notable impact on lighting performance. The increase in concentration of yellow-green-emitting SrBaSiO 4 :Eu phosphor also promotes the color performance and lumen output of WLED devices at high correlated color temperature around 8500K. This is the first time this approach is applied and it results can be utilized for better understanding of optical properties interaction with phosphor materials. Although SrBaSiO 4 :Eu 2+ receives many positive responses, we still need to limit it concentration for high SrBaSiO 4 :Eu 2+ concentration is detrimental to CQS. The appropriate choice of concentration and size of SrBaSiO 4 :Eu is the principal factor to decide the performance of MCW-LEDs. 2+ 2+ 2+
The application of green YF3:Er3+,Yb3+ and red MgSr3Si2O8:Eu2+,Mn2+ layers to...TELKOMNIKA JOURNAL
White light-emitting diodes (WLEDs) with quantum dots (QDs) and phosphor have pulled in huge consideration because of their incredible shading rendering capacity. In the bundling procedure, a QDs film and a phosphor silicone layer will in general be isolated for lessening the reabsorption misfortunes and keeping the QDs surface molecules in a good condition. This examination explored the bundling succession of QDs and phosphor layers to the optical and warm exhibitions of WLEDs. The emitted optical power and PL spectra were estimated and dissected, while an infrared warm imager was utilized to reenact and approve tentatively the temperature fields. The results reveal that at 60 mA, WLEDs with green QDs-on-phosphor type accomplished lumen output (LO) of 1578 lm, with shading rendering record (CRI) of Ra = 60, while the red QDs-on-phosphor type WLEDs exhibited lower LO of 1000 lm, with Ra = 82. In addition, the QDs-onphosphor type WLEDs generated less warmth than the other, and as a result, the most noteworthy temperature in this packaged type was lower than the other. Additionally, its temperature contrast can arrive at 12.3°C. Along these lines, regarding bundling arrangement, the QDs-on-phosphor type is an ideal bundling design to better the optical productivity and shading rendering capacity, as well as lower gadget temperature.
Utilizing CaCO 3 , CaF 2 , SiO 2 , and TiO 2 particles to enhance color hom...IJECEIAES
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 CaCO 3 , CaF 2 , SiO 2 , and TiO 2 , are combined with yellow phosphor Y 3 Al 5 O 12 :Ce 3+ 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 TiO 2 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 SiO 2 grains, we can accomplish higher lumen output at all particle sizes. Meanwhile, the application of 30% CaCO 3 can decreas the CCT deviation by 620 K making CaCO 3 the potential particle to be selected for chromatic quality and light output enhancement of pc-LEDs.
Na3Ce(PO4)2:Tb3+ and Na(Mg2–xMnX)LiSi4O10F2:Mn phosphors: a suitable selectio...TELKOMNIKA JOURNAL
This document discusses a triple-layer remote phosphor structure (TRP) to enhance the color quality and luminous flux of white light-emitting diodes (WLEDs). The TRP structure contains three phosphor layers arranged from bottom to top: yellow YAG:Ce3+ phosphor, green Na3Ce(PO4)2:Tb3+ phosphor, and red Na(Mg2–xMnX)LiSi4O10F2:Mn phosphor. Simulation results show that the red phosphor improves color rendering index while the green phosphor improves luminous flux but reduces color rendering index. The color quality scale is maximized when there is a balance between the yellow,
Improving color quality and luminous flux of white LED utilizing triple-layer...IJECEIAES
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 K, 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.
Acquiring higher lumen efficacy and color rendering index with green NaYF4:Er...TELKOMNIKA JOURNAL
Lighting devices that apply diodes to create white light-emitting diodes (WLEDs) can achieve remarkable results in color quality, especially those containing quantum dots (QDs) and phosphor. The technique to create an appropriate package is providing spaces between the QDs and phosphor components which helps decrease the ratio of the reabsorption losses and keeps the QDs surface ligands constant. The research aims to perfect the constructing method of remote phosphor configuration containing quantum dots and phosphor materials that based on lighting properties and temperature feature of WLEDs. The infrared thermography is the tool to measure and analyze total emitted light and emission ranges of the device. This device is also used in temperature simulation and experimental verification. At the given mA of 60, the WLEDs structure with green QDs layer above the phosphor layer results in 996 lm luminous flux (LF), and Ra = 57 in color rendering ability. Meanwhile, luminous flux of WLEDs with red QDs-on-phosphor structure is 632, and Ra = 70. Furthermore, comparing with the green QDs-on-phosphor type, the red QDs-on-phosphor type emitted less LF. However, the red QDs-on-phosphor type can be the most effective package design to achieve color rendering ability.
Comparison of calcium carbonate and titania particles on improving color homo...TELKOMNIKA JOURNAL
1) The document compares the effects of adding calcium carbonate (CaCO3) and titania (TiO2) particles to yellow phosphor in phosphor-converted LEDs (pc-LEDs) to improve color uniformity and luminous flux.
2) Simulation results show that pc-LEDs with 30% CaCO3 concentration have a 620K lower correlated color temperature deviation compared to no additional particles, indicating better color uniformity. In contrast, increasing TiO2 concentration sharply reduces luminous flux.
3) CaCO3 particles are recommended for achieving both higher color homogeneity and lumen output in pc-LEDs due to their scattering properties being more equal between blue and yellow light wavelengths.
LaSiO 3 Cl:Ce 3+ ,Tb 3+ and Mg 2 TiO 4 :Mn 4+ : quantum dot phosphors for im...IJECEIAES
In this research, we focus on the solutions to enhance the lighting properties as well as the heat regulation of the white light-emitting diodes (WLEDs) with conventional phosphor and quantum dots (QDs). Although receiving lots of attention for being an innovative lighting solution with good color rendering index, the potentials of WLEDs conjugated with quantum dots (QDS), especially the QDs-phosphor mixed nanocomposites ones, are restrained due to the lacking performance in the aspects mentioned above. The crucial requirement to produce better WLEDs is finding solutions that improve the lacking aspects, therefore, through observing previous studies and applying advanced technique, this research suggest an effective and unique packaging configuration, in which the nanocomposites QDs-phosphor layer is set horizontally to the WLED. This novel packaging configuration allow WLED performance in terms of lighting and heating to reach it peaks. This is the first time four different types of WLEDs, singlelayer phosphor, dual-layer remote phosphor with yellow-red and yellow-green, and triple-layer phosphor, were simulated, utilized and compared in one study to decide the best WLED configuration. The results show that the triple-layer phosphor configurations improve the color rendering ability and lumen output better than the other configurations.
Enhancing the CRI and lumen output for the 6600 K WLED with convex-dual-layer...IJECEIAES
The traditional white LED product established with a single chip and a single phosphor results in a low color rendering index (CRI). The upgrade of LED package is comprised of two chips and one phosphor material and gives the higher CRI while keeping high luminous efficiency. Based on previous findings, the research paper performs the application of the two chips and two phosphors to enhance the color tunability of LEDs with different amounts and intensities of the two employed phosphors. Additionally, a color design model is built to serve the purpose of bettering the color fine-tuning of the white-light LED module. The maximum value of the difference between the measured CIE 1931 color coordinates and that of the simulated model is approximately 0.0063 around the 6600 K correlated color temperature (CCT). From the results, this study offers a quick approach to achieve the color fine tuning of a white-light LED module with a high CRI and luminous efficiency.
Effect of morphology on the photoelectrochemical performance of nanostructure...Pawan Kumar
This document discusses the effect of morphology on the photoelectrochemical performance of nanostructured Cu2O photocathodes. It summarizes that:
1) Different deposition methods including electroreduction, anodization, thermal oxidation, and chemical oxidation were used to deposit planar and 1D nanostructured Cu2O thin films on copper foil with varying morphologies.
2) Mesoscopic and planar Cu2O morphologies exhibited large differences in carrier density and charge transfer resistance, but these differences did not strongly influence their photoelectrochemical performance.
3) Planar Cu2O deposited via electroreduction provided the highest photocurrent density of 5.0 mA cm−2 at 0 V vs RHE,
Application of dual-layer phosphor geometries for enhancing the optical prope...TELKOMNIKA JOURNAL
This article compares the lumen output of two packages of two-remote phosphor (RP). The first package is flat dual-remote phosphor (FDRPS). The second package is concave dual-remote phosphor (CDRP). The dispersion qualities of the white-light-emitting diode are different as a result of their different cover designs, leading to a disparity between the FDRPS and CDRPS configurations. The results of the study show that the FDRPS package yields a lumen output superior to that of the CDRPS package. In the article, we can also see how the space among the phosphor films (𝑑1) and the space among the phosphor film and the light emitting diodes (LED) outer side (𝑑2) might affect the light characteristics in the CDRPS model. As the indicated distances shift, the characteristics of dispersion and absorptivity in the distant phosphor film will shift as well. Such an occurrence can have an impact on chromatic uniformity as well as optical performance in white light emitting diodes (WLEDs). If we modify the and values, it is necessary to change the phosphor YAG:Ce3+ concentration in the WLEDs to keep the correlated color temperature at 8500 K.
Research on advancing chromatic reproduction and luminosity of a WLED using t...TELKOMNIKA JOURNAL
In this study, the use of triple-sheet phosphor arrangement (TRP) in performing significant improvements to both color quality and luminous flux of white light emitting diode (WLEDs) is introduced. The phosphor layer of CaLaB3O7:Ce3+,Mn2+ is to accomplish green-spectra enhancement for the boost of luminous efficacy (LE), while MgB2O4:Mn2+ red phosphor layer is for red-spectra enhancement to better color rendering index (CRI) of WLEDs. The changes in these two phosphors’ concentrations present considerable effects on the yellow phosphor YAG:Ce3+ concentration, the color quality scale (CQS), CRI, and LE. Findings display the decrease of YAG:Ce3+ concentration accompanying the increase of red and green phosphor concentrations, for the stabilized average correlated color temperatures (ACCTs) between 6000 and 8500 K. Results also reveal that greater content of MgB2O4:Mn2+ leads to greater CRI value. Meanwhile using the increasing CaLaB3O7:Ce3+,Mn2+ concentration, the CRI lowers considerably. CQS, on the other hand, can increase with CaLaB3O7:Ce3+,Mn2+ concentration from 10% to 14%. Especially, given the enhancement for the CRI as well as CQS, LE value will surge to more than 40% due to the reduction of scattering light and the addition of green light. The outcome of the study is a priceless reference for light emitting diode (LED) producers.
Improving luminous flux and color homogeneity of dual-layer phosphor sctructureTELKOMNIKA JOURNAL
In order to clarify the main purpose of the study, we put a green phosphor layer SrBaSiO4:Eu2+
on the yellow phosphorus layer YAG:Ce3+ through using only one WLEDs structure in different color
temperatures like 5600 K, 6600 K, 7700 K. Then, we find the suitable SrBaSiO4:Eu2+ concentration in order
that the luminous flux could get the highest value. The results show that SrBaSiO4:Eu2+ brings great
benefits to increase not only optical gain but also color uniformity. Specifically, the greater
the SrBaSiO4:Eu2+ concentration, the greater the output of WLEDs because of the development of green
light component in WLEDs. However, only if the SrBaSiO4:Eu2+ concentration exceeds the level, a slight
decrease in color rendering index (CRI) can occur, which based on Monte Carlo simulation. In addition,
the results of this paper have contributed significantly to the creation of higher-powered WLEDs.
The improvement of the color rendering index using convex-dual-layer remote p...TELKOMNIKA JOURNAL
White-light emitting diodes (WLEDs) are semiconductor light sources whose construction design is usually made up of a single pumping chip and a single light-conversion film of phosphor compound. The outstanding problem of this traditional setting is the inadequate chroma rendering index (CRI). Introducing a cluster of multiple blue chips with more than one phosphor layer is demonstrated to address that flaw of W-LEDs. This package is called the dual-film remote-phosphor multi-chip WLED. As a consequence, both the light brightness and the CRI are improved. However, for the maximum results, the test on the second layer of phosphor has been performed to continually alter the proportions and densities of phosphor within the silicone. The researchers employed a unique hue design to control the white-light light emitting diode (LED) module. When comparing the actual result to the simulated color coordinates under the hue standard of international commission on illumination (CIE) 1931, the highest difference is found to be around 0.0063 for correlated color temperatures (CCT) of 6600 K and 7700 K. Experiments indicate that the setting of multi-chip and dual-phosphorus is the optimal design for supporting CRI quality and luminous intensity.
The better distant phosphor configurations for enhancing WLED color intensity...TELKOMNIKA JOURNAL
The distant phosphor configuration produces more illuminating beams than the two settings containing conformal or in-cup phosphor. When this configuration is used, though, it is difficult to manage the color standard of light-emitting diodes (LEDs). As a result, in past few years, numerous studies have focused on controlling the color standard of distant phosphor configurations. Until present, two distant phosphor configurations of single- and triple-film phosphor configurations, have been used to improve color standards. This research will investigate the ideal configuration among these configurations in terms of color rendering index (CRI), color quality scale (CQS), lumen output (LO), as well as color homogeneity for multi-chip white LEDs (WLEDs). WLEDs, operating at five different temperatures of color between 5600 K and 8500 K, are used to perform the studies. The results reveal that the three-sheet phosphor setting would be more desirable, with greater CRI, CQS, and lumen efficiency (LE) indexes. Furthermore, when using a triple-layer phosphor arrangement, color variation is reduced, resulting in a rise in color consistency. This conclusion is possibly verified by using Mie theory to analyze scattering properties in distant phosphor setup, making the study findings legitimate and important data to produce more advanced WLEDs.
LaSiO 3 Cl:Ce 3+ ,Tb 3+ and Mg 2 TiO 4 :Mn 4+ : quantum dot phosphors for im...IJECEIAES
In this research, we focus on the solutions to enhance the lighting properties as well as the heat regulation of the white light-emitting diodes (WLEDs) with conventional phosphor and quantum dots (QDs). Although receiving lots of attention for being an innovative lighting solution with good color rendering index, the potentials of WLEDs conjugated with quantum dots (QDS), especially the QDs-phosphor mixed nanocomposites ones, are restrained due to the lacking performance in the aspects mentioned above. The crucial requirement to produce better WLEDs is finding solutions that improve the lacking aspects, therefore, through observing previous studies and applying advanced technique, this research suggest an effective and unique packaging configuration, in which the nanocomposites QDs-phosphor layer is set horizontally to the WLED. This novel packaging configuration allow WLED performance in terms of lighting and heating to reach it peaks. This is the first time four different types of WLEDs, singlelayer phosphor, dual-layer remote phosphor with yellow-red and yellow-green, and triple-layer phosphor, were simulated, utilized and compared in one study to decide the best WLED configuration. The results show that the triple-layer phosphor configurations improve the color rendering ability and lumen output better than the other configurations.
Quantum dot phosphors CaS:Ce3+ and CaS:Pb2+, Mn2+ for improvements of white ...IJECEIAES
The goal of this study is to discover a new method that uses standard phosphors and quantum dots to improve the lighting qualities and heat manipulation of white light-emitting diodes (WLEDs). Despite the popularity as a good ingredient that offers good color rendering properties, quantum dots (QDs) have not been widely employed in the fabrication of WLEDs, particularly, the utilization of QDs-phosphor-mixed nanocomposite is limited. We propose a unique packaging design based on the research’s experimental findings. The layer of nanocomposites consisting of QDs and phosphors is horizontally positioned to the WLED for optimal lighting and heating efficiency. This study simulated and used four distinguishing white LEDs forms: mono-layer phosphorus, two double-layer remote phosphors featuring yellowish-red and yellowish-green organizations, and a triple-layer phosphor. In terms of color rendering and luminous outputs, the triple-layer phosphor configuration outperforms the other implementations, as per the finding.
Employing SiO2 nano-particles in conformal and in-cup structures of 8500 K wh...journalBEEI
SiO2 nano-particles have been examined in a distant phosphor structure for the elevated luminous quality and better consistency of white light-emitting diodes with angular-dependent associated color temperature (CCT). The luminous scattering ability could be increased by applying SiO2 nano-particles contain silicone to the outside of the phosphorus coating. In specific, the strength of blue light at wide angles is increased and differences in CCT can be minimized. In addition, owing to the sufficient refractive indices of silicone-containing SiO2 nanoparticles between the air and phosphorus layers, the luminous flux was improved. This new configuration decreases angular-dependent CCT deviations in the range of -700 to 700 from 1000 to 420 K. In comparison, at a 120 mA driving current, the rise of lumen flux increased by 2.25% relative to an usual distant phosphor structure without SiO2 nano-particles. As a result, in a distant phosphor structure, the SiO2 nano-particles could not only enhance the uniformity of illumination but also enhance the output of light.
Chroma consistency and luminous efficacy for a WLED using remote phosphor con...TELKOMNIKA JOURNAL
The light quality of white-light-emitting diodes (WLEDs), an essential element for the improvement of WLEDs performance, can now be estimated by the angular color uniformity (ACU). In this study, a single
micro-patterned layer is used to compare the variations between the traditional remote phosphor (RP) layer and the remote phosphor layer (single remote micro-patterned phosphor film (RMPP) layer). Furthermore,
we investigate the application of a novel triple remote phosphor layer to improve the ACU in RP down-light lamps. Besides, the optical efficiency of the layers as well as the distribution for the angular correlated color temperature (ACCT) were also measured experimentally. According to the findings, the dual-RMPP-layer structure can achieve better chromatic uniformity with just 441 K of correlated color temperature (CCT) variance. Meanwhile, the single RMPP layer shows an ACCT deviation of 556 K and RP film structure of 1390 K. The simulation incorporating e finite-difference time-domain (FDTD) as well as the approach of ray-tracing ensures an increase in ACU. Furthermore, compare to the traditional RP layer,
the single and dual RMPP layers configuration result in respective luminous efficiency ameliorations of 6.68% and 4.69%. The scattering principle and combining influence from the micro-molded layer may explain the enhancement in ACU as well as lumen.
Using SiO 2 nano-particles for better color uniformity and lumen output in 8...IJECEIAES
In the effort of improving the performance of white light LEDs devices (WLEDs), the SiO 2 nano-particles were applied and have shown a significant impact on the optical properties. Specifically, the light output of the lighting devices is enhanced when a mixture of SiO 2 particles and silicone gel is diffused on the encapsulation layer surface. This enhancement is the result of light scattering from SiO 2 that strengthens the emitted blue light at further angles and reduces the color discrepancy. The evidence is that CCT deviation in SiO 2 -doped structure decline from 1000 K to 420 K in -70° to 70°. In addition, the SiO 2 with refractive index in between the phosphor material and outside environment allows light to be emitted outward more effectively. This lighting enhancement of SiO 2 -doped structure increases the lumen output by 2.25% at 120 mA power source in comparison to structure without SiO 2 . These experimental outcomes suggest that SiO 2 is an effective material to add in WLEDs structure for better lighting efficiency.
Application of triple-layer remote phosphor configuration results in the colo...TELKOMNIKA JOURNAL
This study proposed the triple-layer remote phosphor (TRP) structure to enhance the color quality and the emitted luminous flux of white LEDs (WLEDs). The TRP structure consists of three different phosphor layers that are arranged as follows: the yellow YAG:Ce3+ phosphor at the bottom, the red phosphor layer CaMgSi2O6:Eu2+,Mn2+ at the top and the green Ba2Li2Si2O7:Sn2+,Mn2+ phosphor between these two ones. The aim to use the red CaMgSi2O6:Eu2+,Mn2+ phosphor is to control the red light component so that the color rendering index (CRI) could be increased. While the green Ba2Li2Si2O7:Sn2+,Mn2+ phosphor is applied to manage the green light component, leading to the rise in luminous efficacy (LE) of WLEDs. Moreover, when the concentrations of these two phosphors are raised, that of the yellow phosphor YAG:Ce3+ has to be decreased to remain the average correlated color temperatures (ACTTs) in a range from 6000 K to 8500 K. Furthermore, not only the CRI and LE but the color quality scale (CQS) is also analyzed by controlling the two green and red phosphor concentrations. The researched results show that the higher the concentration of CaMgSi2O6:Eu2+,Mn2+, the more enhancements in the CRI will be made. In contrast, when the Ba2Li2Si2O7:Sn2+,Mn2+ concentration increases, the CRI significantly decreases. Meanwhile, CQS is likely to considerably rise in a concentration range from 10% to 14% of CaMgSi2O6:Eu2+,Mn2+, regardless of the presence of Ba2Li2Si2O7:Sn2+,Mn2+ concentration. Especially, in parallel with the improvement of CRI and CQS, the LE could be also increased by more than 40% due to the decline in back-scattering lights and the green lights supplement. From these details, the results of this study are valuable references for manufacturers to achieve the goals of enhancing color quality and luminous efficiency of WLEDs.
Enhance the chromatic uniformity and luminous efficiency of WLEDs with triple...IJECEIAES
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.
Using phosphor ZnB2O4:Mn2+ for enhancing the illuminating beam and hue standa...TELKOMNIKA JOURNAL
The enhancement in hue uniformity and luminous production of multiple-chip white LED lamps (MCW-LEDs) using dual-layer remote phosphor packaging designs are the emphases of this paper. We blended Mn2+ activated strontium–barium silicate (ZnB2O4:Mn2+) with the phosphor mixture and manage to record significant impacts of this new phosphor mixture on the LED lights’ lighting performance. There is evidence that the growing concentration of yellow-green-emitting ZnB2O4:Mn2+ phosphor encourages the enhancement of hue uniformity and illumination effectiveness in MCW-LEDs with mean correlated hue heats (CCTs) of roughly 8500 K, though the color quality scale is gradually deteriorating. It is possible to successfully achieve such amazing MCW-LED performance if we choose the right concentration and size of ZnB2O4:Mn2+.
Effects of NaB2O4:Mn2+ and Ba2Li2Si2O7:Sn3+,Mn2+ phosphors and remote structu...journalBEEI
In order to increase the optical features of white light-emitting diodes (WLEDs), quantum dots (QDs) and phosphor materials have been proposed because of outstanding performance. The configuration of WLEDs with QDs layer and phosphor-silicone layer suggested placing these components separately to limit light loss, and enhance consistency at contact surface of QDs. In this research, the effects of QDs and phosphor on the performance of WLEDs are concluded through experiments. The emitted light and PL spectra were examined thoroughly, and infrared thermal imagers were applied to simulate the heat generation of an actual WLED device. The results show that with the configuration of 60 mA energy source, WLEDs which has the QDs-on-phosphor form attained luminous efficiency (LE) of 110 lm/W, with color rendering index (CRI) of Ra=92 and R9=80, whereas the WLEDs which has the phosphor-on-QDs form only has 68 lm/W in LE, Ra=57 and R9=24. Furthermore, WLEDs which has the QDs-on-phosphor form has less high temperature generated at the components’ conjunction in comparison to the counterpart, the peak generated heat in QDs-on-phosphor WLEDs is also lower and the heating capacity gap between 2 structures can go up to 12.3°C.
Using triple-layer remote phosphor structures LaVO4:Eu3+ and ZnS:Cu,Sn to imp...TELKOMNIKA JOURNAL
This research paper investigates the novel triple remote phosphor layer for improving the remote phosphor’s angular chroma uniformity (ACU) of down-light lamps by using remote micro-patterned phosphor layers (RMPP). In addition, introducing the triple-layer (TL) RMPP is introduced to offer the potential approach to this objective. This analysis also measures the optical efficiency of the layers and the angle distribution of angular correlated color temperature (ACCT). Drawing a comparison between the traditional
dual-layer (DL) RMPP and the proposed TL is furthermore critical to this study. According to the findings, the triple-layer phosphor configuration can achieve greater hue consistency while having a correlating colour temperature (CCT) variance merely measured at 441 K. Results in the single RMPP layer are 1390 K of the remote phosphor (RP) sheet setting and
556 K for the ACCT deviation. The recreation employing finite-difference
time-domain (FDTD) as well as the approach of ray-tracing ensures an increase in angular color uniformity (ACU). The structure of DL and TL RMPPs results in a 6.68 % and 4.69 % gain in luminous efficiency, respectively, with the standard RMPP layer at a currently driving of 350 mA. The micro-patterned layer’s scattering characteristic and mixing effect may account for the increased ACU and luminous efficiency.
For improvements in chromatic scales and luminescent fluxes of white lights: ...TELKOMNIKA JOURNAL
This study compares red-phosphor LaOF:Eu3+ impacts on a single-film remote phosphor configuration (SRPC) and a double-film remote phosphor configuration (DRPC). Mie theory is used to demonstrate the relationship between light flux and color quality. SRPC is a phosphor layer consisting of LaOF:Eu3+ particles mixed with YAG:Ce3+. Meanwhile, DRPC is two separate films of red and yellow phosphors. To increase scattering properties, we added 5% SiO2 into phosphor layers. The differences in structure affect significantly white light emitting diodes’ (WLEDs’) optical properties. Attained figures and statistics show that the color rendering indices (CRIs) increase along with the concentrations of both structures, and these numbers are approximately similar. However, DPRC exhibits a color quality scale (CQS) of 74 in all examined chromatic temperatures (5600 K - 8500 K), which is greater than SRPC’s 71 at 8500 K. Besides, the luminous efficiencies (LEs) in DRPC are more outstanding than that of SRPC, at given LaOF:Eu3+ concentration percentages (2%-14%). To summarize, DRPC offers greater benefits in luminous flux and color quality, compared to SRPC. Choosing the proper red light phosphor concentration, on the other hand, becomes a crucial aspect of achieving the ideal CQS and LEs.
Similar to Improvement of double-layer phosphor structure WLEDS in color homogeneity and luminous flux (16)
Square transposition: an approach to the transposition process in block cipherjournalBEEI
The transposition process is needed in cryptography to create a diffusion effect on data encryption standard (DES) and advanced encryption standard (AES) algorithms as standard information security algorithms by the National Institute of Standards and Technology. The problem with DES and AES algorithms is that their transposition index values form patterns and do not form random values. This condition will certainly make it easier for a cryptanalyst to look for a relationship between ciphertexts because some processes are predictable. This research designs a transposition algorithm called square transposition. Each process uses square 8 × 8 as a place to insert and retrieve 64-bits. The determination of the pairing of the input scheme and the retrieval scheme that have unequal flow is an important factor in producing a good transposition. The square transposition can generate random and non-pattern indices so that transposition can be done better than DES and AES.
Hyper-parameter optimization of convolutional neural network based on particl...journalBEEI
The document proposes using a particle swarm optimization (PSO) algorithm to optimize the hyperparameters of a convolutional neural network (CNN) for image classification. The PSO algorithm is used to find optimal values for CNN hyperparameters like the number and size of convolutional filters. In experiments on the MNIST handwritten digit dataset, the optimized CNN achieved a testing error rate of 0.87%, which is competitive with state-of-the-art models. The proposed approach finds optimized CNN architectures automatically without requiring manual design or encoding strategies during training.
Supervised machine learning based liver disease prediction approach with LASS...journalBEEI
In this contemporary era, the uses of machine learning techniques are increasing rapidly in the field of medical science for detecting various diseases such as liver disease (LD). Around the globe, a large number of people die because of this deadly disease. By diagnosing the disease in a primary stage, early treatment can be helpful to cure the patient. In this research paper, a method is proposed to diagnose the LD using supervised machine learning classification algorithms, namely logistic regression, decision tree, random forest, AdaBoost, KNN, linear discriminant analysis, gradient boosting and support vector machine (SVM). We also deployed a least absolute shrinkage and selection operator (LASSO) feature selection technique on our taken dataset to suggest the most highly correlated attributes of LD. The predictions with 10 fold cross-validation (CV) made by the algorithms are tested in terms of accuracy, sensitivity, precision and f1-score values to forecast the disease. It is observed that the decision tree algorithm has the best performance score where accuracy, precision, sensitivity and f1-score values are 94.295%, 92%, 99% and 96% respectively with the inclusion of LASSO. Furthermore, a comparison with recent studies is shown to prove the significance of the proposed system.
A secure and energy saving protocol for wireless sensor networksjournalBEEI
The research domain for wireless sensor networks (WSN) has been extensively conducted due to innovative technologies and research directions that have come up addressing the usability of WSN under various schemes. This domain permits dependable tracking of a diversity of environments for both military and civil applications. The key management mechanism is a primary protocol for keeping the privacy and confidentiality of the data transmitted among different sensor nodes in WSNs. Since node's size is small; they are intrinsically limited by inadequate resources such as battery life-time and memory capacity. The proposed secure and energy saving protocol (SESP) for wireless sensor networks) has a significant impact on the overall network life-time and energy dissipation. To encrypt sent messsages, the SESP uses the public-key cryptography’s concept. It depends on sensor nodes' identities (IDs) to prevent the messages repeated; making security goals- authentication, confidentiality, integrity, availability, and freshness to be achieved. Finally, simulation results show that the proposed approach produced better energy consumption and network life-time compared to LEACH protocol; sensors are dead after 900 rounds in the proposed SESP protocol. While, in the low-energy adaptive clustering hierarchy (LEACH) scheme, the sensors are dead after 750 rounds.
Plant leaf identification system using convolutional neural networkjournalBEEI
This paper proposes a leaf identification system using convolutional neural network (CNN). This proposed system can identify five types of local Malaysia leaf which were acacia, papaya, cherry, mango and rambutan. By using CNN from deep learning, the network is trained from the database that acquired from leaf images captured by mobile phone for image classification. ResNet-50 was the architecture has been used for neural networks image classification and training the network for leaf identification. The recognition of photographs leaves requested several numbers of steps, starting with image pre-processing, feature extraction, plant identification, matching and testing, and finally extracting the results achieved in MATLAB. Testing sets of the system consists of 3 types of images which were white background, and noise added and random background images. Finally, interfaces for the leaf identification system have developed as the end software product using MATLAB app designer. As a result, the accuracy achieved for each training sets on five leaf classes are recorded above 98%, thus recognition process was successfully implemented.
Customized moodle-based learning management system for socially disadvantaged...journalBEEI
This study aims to develop Moodle-based LMS with customized learning content and modified user interface to facilitate pedagogical processes during covid-19 pandemic and investigate how teachers of socially disadvantaged schools perceived usability and technology acceptance. Co-design process was conducted with two activities: 1) need assessment phase using an online survey and interview session with the teachers and 2) the development phase of the LMS. The system was evaluated by 30 teachers from socially disadvantaged schools for relevance to their distance learning activities. We employed computer software usability questionnaire (CSUQ) to measure perceived usability and the technology acceptance model (TAM) with insertion of 3 original variables (i.e., perceived usefulness, perceived ease of use, and intention to use) and 5 external variables (i.e., attitude toward the system, perceived interaction, self-efficacy, user interface design, and course design). The average CSUQ rating exceeded 5.0 of 7 point-scale, indicated that teachers agreed that the information quality, interaction quality, and user interface quality were clear and easy to understand. TAM results concluded that the LMS design was judged to be usable, interactive, and well-developed. Teachers reported an effective user interface that allows effective teaching operations and lead to the system adoption in immediate time.
Understanding the role of individual learner in adaptive and personalized e-l...journalBEEI
Dynamic learning environment has emerged as a powerful platform in a modern e-learning system. The learning situation that constantly changing has forced the learning platform to adapt and personalize its learning resources for students. Evidence suggested that adaptation and personalization of e-learning systems (APLS) can be achieved by utilizing learner modeling, domain modeling, and instructional modeling. In the literature of APLS, questions have been raised about the role of individual characteristics that are relevant for adaptation. With several options, a new problem has been raised where the attributes of students in APLS often overlap and are not related between studies. Therefore, this study proposed a list of learner model attributes in dynamic learning to support adaptation and personalization. The study was conducted by exploring concepts from the literature selected based on the best criteria. Then, we described the results of important concepts in student modeling and provided definitions and examples of data values that researchers have used. Besides, we also discussed the implementation of the selected learner model in providing adaptation in dynamic learning.
Prototype mobile contactless transaction system in traditional markets to sup...journalBEEI
1) Researchers developed a prototype contactless transaction system using QR codes and digital payments to support physical distancing during the COVID-19 pandemic in traditional markets.
2) The system allows sellers and buyers in traditional markets to conduct fast, secure transactions via smartphones without direct cash exchange. Buyers scan sellers' QR codes to view product details and make e-wallet payments.
3) Testing showed the system's functions worked properly and users found it easy to use and useful for supporting contactless transactions and digital transformation of traditional markets. However, further development is needed to increase trust in digital payments for users unfamiliar with the technology.
Wireless HART stack using multiprocessor technique with laxity algorithmjournalBEEI
The use of a real-time operating system is required for the demarcation of industrial wireless sensor network (IWSN) stacks (RTOS). In the industrial world, a vast number of sensors are utilised to gather various types of data. The data gathered by the sensors cannot be prioritised ahead of time. Because all of the information is equally essential. As a result, a protocol stack is employed to guarantee that data is acquired and processed fairly. In IWSN, the protocol stack is implemented using RTOS. The data collected from IWSN sensor nodes is processed using non-preemptive scheduling and the protocol stack, and then sent in parallel to the IWSN's central controller. The real-time operating system (RTOS) is a process that occurs between hardware and software. Packets must be sent at a certain time. It's possible that some packets may collide during transmission. We're going to undertake this project to get around this collision. As a prototype, this project is divided into two parts. The first uses RTOS and the LPC2148 as a master node, while the second serves as a standard data collection node to which sensors are attached. Any controller may be used in the second part, depending on the situation. Wireless HART allows two nodes to communicate with each other.
Implementation of double-layer loaded on octagon microstrip yagi antennajournalBEEI
This document describes the implementation of a double-layer structure on an octagon microstrip yagi antenna (OMYA) to improve its performance at 5.8 GHz. The double-layer consists of two double positive (DPS) substrates placed above the OMYA. Simulation and experimental results show that the double-layer configuration increases the gain of the OMYA by 2.5 dB compared to without the double-layer. The measured bandwidth of the OMYA with double-layer is 14.6%, indicating the double-layer can increase both the gain and bandwidth of the OMYA.
The calculation of the field of an antenna located near the human headjournalBEEI
In this work, a numerical calculation was carried out in one of the universal programs for automatic electro-dynamic design. The calculation is aimed at obtaining numerical values for specific absorbed power (SAR). It is the SAR value that can be used to determine the effect of the antenna of a wireless device on biological objects; the dipole parameters will be selected for GSM1800. Investigation of the influence of distance to a cell phone on radiation shows that absorbed in the head of a person the effect of electromagnetic radiation on the brain decreases by three times this is a very important result the SAR value has decreased by almost three times it is acceptable results.
Exact secure outage probability performance of uplinkdownlink multiple access...journalBEEI
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Improvement of double-layer phosphor structure WLEDS in color homogeneity and luminous flux
1. Bulletin of Electrical Engineering and Informatics
Vol. 10, No. 5, October 2021, pp. 2513~2519
ISSN: 2302-9285, DOI: 10.11591/eei.v10i5.2914 2513
Journal homepage: http://beei.org
Improvement of double-layer phosphor structure WLEDS in
color homogeneity and luminous flux
Dieu An Nguyen Thi1
, Phung Ton That2
, Hoang Nam Nguyen3
1
Faculty of Electrical Engineering Technology, Industrial University of Ho Chi Minh City, Vietnam
2
Faculty of Electronics Technology, Industrial University of Ho Chi Minh City, Vietnam
3
Modeling Evolutionary Algorithms Simulation and Artificial Intelligence, Faculty of Electrical and Electronics
Engineering, Ton Duc Thang University, Vietnam
Article Info ABSTRACT
Article history:
Received Feb 25, 2021
Revised May 20, 2021
Accepted Jul 10, 2021
The concept of the analysis is to put a CaAl2O4:Mn2+
green phosphor layer on
top of the YAG:Ce3+
yellow phosphor layer. After that, find the added
CaAl2O4:Mn2+
concentration appropriate for the highest luminous flux (LF)
and color homogeneity (CH). In this analysis, five equivalent WLEDs were
applied but with distinct color temperatures, including 5600 K - 8500 K. The
findings showed that CaAl2O4:Mn2+
brings great benefits to increase not only
the luminous flux but also the color homogeneity. Especially, the higher the
CaAl2O4:Mn2+
concentration, the more the luminous flux released by WLEDs,
owing to the risen content of the light of green in WLEDs. Nevertheless, as
the CaAl2O4:Mn2+
concentration raised significantly, a small reduction in the
color rendering metric (CRI) and color quality scale (CQS) occurred. This is
supported by simulation and calculation according to the theory of Monte
Carlo. The paper results are the crucial contribution to the manufacture of
WLEDs with better optical performance and color homogeneity of remote
phosphor configurations.
Keywords:
Color homogeneity
Double-layer phosphor
Luminous flux
Monte Carlo theory
WLEDs
This is an open access article under the CC BY-SA license.
Corresponding Author:
Hoang Nam Nguyen
Modeling Evolutionary Algorithms Simulation and Artificial Intelligence
Faculty of Electrical and Electronics Engineering
Ton Duc Thang University
No. 19 Nguyen Huu Tho Street, Tan Phong Ward, District 7, Ho Chi Minh City, Vietnam
Email: nguyenhoangnam@tdtu.edu.vn
1. INTRODUCTION
The fourth potential illumination source generation used to replace the traditional one, phosphor
transformed white light emitting diodes (pc-WLEDs), which has a wide range of prospects in lighting
solutions, as can be shown in [1]-[5]. The implementation of white light emitting diodes has become
increasingly popular in various areas of everyday routine of people, such as landscape, street lighting,
backlighting, while the efficiency of illumination harness and the consistency of angles of the associated
chromatic temperature of the white LEDs are still the demanding factors that limit its enhancement [6]-[8].
Future advancements in luminescent performance and color consistency are critical, given the steady growth
in consumer demand and implementations [9], [10]. A combination of the light of blue from the reverse red
phosphorus with the light of yellow from the LED chip is the most common method for producing white light
today. While this idea seems to be very common, it cannot be denied that the layout of LEDs and the layout
of phosphorous layers, especially the color rendering index, play a significant role in assessing the luminous
quality [11]-[14]. Several common methods of phosphorus coating have been suggested in order to
manufacture LEDs, such as dispensing and conformal coatings [15]-[18]. Still, these configurations do not
2. ISSN: 2302-9285
Bulletin of Electr Eng & Inf, Vol. 10, No. 5, October 2021 : 2513 – 2519
2514
have good lighting chromaticity due to the deterioration of the illuminating transformation of phosphorus
matter caused by the yellow emitted phosphorus directly contacting the LED chips, leads to a temperature
rise at the juncture of the LED and phosphorus layers. Minimizing the influence of heat will therefore
increase the phosphor's efficiency and keep the phosphorus from being irremediably harmed. A lot of earlier
experiments have shown that the heating effect is reduced with the remote structure of phosphor layers that
are located distant from the heat origin (LED chip). With an adequate space set between the phosphor
compounding and the LED chip, the backscatter and dissemination of inner lighting could be restricted. This
approach is the optimal solution for LED heat control, so the luminous efficiency and color consistency of
LEDs can be increased [19], [20]. The distant phosphor configuration, on the other hand, is adequately suited
for regular illumination but does not meet other demands for many other lighting implementations, which is
perhaps why developing the upcoming generation of LEDs is critical. Several new remote phosphorus
structures were proposed for future developments, with the goal of minimizing phosphorus backscatter to the
chip and improving luminescent efficiency. Some other research found that a reversed cone lens encapsulant
and a distant phosphorus layer covering the ring would redirect light beams from the blue chip to the LED
surface, decreasing internal reflection losses within the LED [21]. A patterned distant phosphorus
configuration with a clear area in the perimeter zone and no coating phosphorus on the outer surface could
achieve optimum dependence of angles associated color temperature homogeneity and chromatic
stabilization [22]. In contrast, the patterned sapphire substrate applied to the remote phosphorus in a far-field
pattern could have even greater homogeneity of the associated color temperature than a standard template
[23], [24]. To enhance the illumination performance of LEDs, distant phosphorus with a double-layer packet
is suggested. The above-mentioned researches did concentrate on enhancing the uniformity of color and
luminous flux performance of phosphorus remote structure WLEDs, yet investigated primarily on single-chip
WLEDs and models with low color temperature. In the meantime, it is difficult to develop the optical
parameters for high color temperature WLEDs.
This article suggests a remote phosphorous double-layer layout to increase the color standard of
WLEDs with varying color temperatures from 5600 K to 8500 K. The novel concept of the article is to utilize
the CaAl2O4:Mn2+
green phosphor layer to raise the composition of green light in WLEDs, leading to better
luminous flux (LF) and color homogeneity (CH). The article reports in detail the combination of chemical
elements of CaAl2O4:Mn2+
affecting the visual properties of WLEDs as well. The results of the article show
that LF and CH significantly improve with the addition of phosphor layers CaAl2O4:Mn2+
. However, to
prevent a deep fall in the color rendering ability (CRI) and color quality ratio (CQS) when the green
phosphorus concentration rises extremely, the adequate CaAl2O4:Mn2+
concentration should be determined.
Three notable points can be reported with the additional layer of green phosphor on top of the layer of yellow
phosphor YAG:Ce3+
are: the increased green light component leading to heightened the spectrum of white
light emitting light, better emitted flux, and higher dispersion and transmittance of WLED illumination with
the risen CaAl2O4:Mn2+
concentration. The selection of proper concentration of CaAl2O4:Mn2+
is therefore
essential for the WLEDs' balance of illuminating beam and color quality.
2. COMPUTATIONAL SIMULATION
2.1. Provision of green-emitting CaAl2O4:Mn2+
phosphor
CaAl2O4:Mn2+
particles are forms of yellow-green phosphorus and become more popular owing to
their peak emission of 2.28 eV and a lot of excellent features such as optimal quantum yield and high
temperature permanence. The particle sizes and concentration of CaAl2O4:Mn2+
phosphors may have a
significant impact on their illumination characteristics. The ingredients consist of CaCO3, Al2O3, MnCO3, CaF2
and Mn2+
ion, all of which, as seen in Table 1, are used as raw materials. In addition, CaAl2O4:Mn2+
is used
especially for fluorescent lamps with very high-loading and a long lifetime. As a result, it is amongst the most
popular phosphors of commercially produced oxide. Overall, the CaAl2O4:Mn2+
manufacturing phase is being
as: First of all, to be combined together, we slurry all the ingredients in the water. They are then ball-milled into
small particles in the water. After that, when they are dried in the air, the materials will be powdered. Next, this
powder will be fired with CO at 1300°C within an hour in covered alumina crucibles and powderized by dry
milling. Then, with CO at 1200°C within an hour, they are fired again in open quartz boats. Eventually, we
wash the product in a liter of water in a solution of NH4Cl and then several times in plain water.
Table 1. Combination of chemical elements of green-emitting phosphor CaAl2O4:Mn2+
Ingredient Mole % By weight (g)
CaCO3 93 93
Al2O3 200 (of Al) 102
MnCO3 2 2.3
CaF2 5 3.9
3. Bulletin of Electr Eng & Inf ISSN: 2302-9285
Improvement of double-layer phosphor structure WLEDS in color … (Dieu An Nguyen Thi)
2515
2.2. Simulation of MC-WLEDs
The layers of phosphors in actual MCW-LEDs are modeled with clear silicone sheets utilizing the
simulating software of LightTools 9.0. This simulation procedure is carried out over two distinct time
periods; (1) it is critical to identify and construct the configuration models and optic features of MCW-LEDs;
(2) the optic impacts of phosphor layers are then well regulated by the CaAl2O4:Mn2+
concentration variation.
To evaluate the effect of YAG:Ce3+
and CaAl2O4:Mn2+
phosphor compounding on the performance of
MCW-LED lamps, some comparisons must be made. Particularly, effects of the green-yellow dual-layer
remote phosphorus model, with mean CCTs of 5600 K-8500 K, are stated and explained. Figure 1 (a), (b),
(c), (d) depicts a detailed overview of a MCW-LED lamp with conformal phosphor compounding and a mean
CCT of 8500 K. Apart from the green phosphor CaAl2O4:Mn2+
, the specifications of other WLED elements
are also expressed. The reflector's base length is 8 mm, its height is 2.07 mm, and its top surface length is
9.85 mm. The conformal phosphor compounding coats nine chips with a thickness of 0.08 mm. Each LED
chip is attached to the reflector space through a squared ground region of 1.14 mm2 and 0.15-mm height. The
reflective radiation of a blue LED chip is 1.16 W, with a wavelength that peaks at 453 nm.
(a) (b)
(c) (d)
Figure 1. Schematic diagrams of WLEDs; (a) real WLEDs, (b) bonding diagram, (c) double-layer phosphor
model illustration, (d) side view of blue chip
3. RESULTS AND ANALYSIS
The reverse mutation among the concentration of green CaAl2O4:Mn2+
and yellow YAG:Ce3+
films
can be seen in Figure 2. There are two meanings of this change: one is to preserve mean CCTs, the other is to
impact the absorption and scattering in WLEDs of two phosphor layers. The color quality and the
performance of luminous flux of WLEDs are ultimately influenced by this. Thus, the selection of
CaAl2O4:Mn2+
concentration defines the color standard of WLEDs. Whenever the CaAl2O4:Mn2+
goes from
2% wt. to 20% wt., the concentration of yellow YAG:Ce3+
declines to preserve the mean CCTs. There is a
similarity with WLEDs with varying CCTs in the range of 5600 K - 8500 K.
Figures 3-7 show the influence of changing concentration of CaAl2O4:Mn2+
green phosphor on the
transmittance range of WLEDs. It is possible to make a decision based on the manufacturer's specifications.
WLEDs that need high color performance can minimize illuminated beam by a minor fraction. White light is
the combination of the spectral field displayed in Figures 3-7. The five figures depict spectra at 5600 K,
6600 K, 7000 K, 7700 K, and 8500 K. Clearly, the intensity trend increases with concentration in two regions
of the lighting spectral range: 420 nm - 480 nm and 500 nm - 640 nm. This increase in the two-band emission
spectra demonstrates an increase in the output luminous flux. Moreover, the blue-light scattering in WLED is
increased, which means the scattering in the phosphorous layer and in WLEDs is increased, resulting in color
uniformity becoming favored. This is a significant finding when CaAl2O4:Mn2+
is used. Controlling the color
uniformity of the high temperature remote phosphor structure, in particular, is hard. This study concluded
4. ISSN: 2302-9285
Bulletin of Electr Eng & Inf, Vol. 10, No. 5, October 2021 : 2513 – 2519
2516
that CaAl2O4:Mn2+
, at both low and high CCTs (5600 K and 8500 K), will improve the color quality of
WLEDs.
Figure 2. Changing the concentration of phosphor
to preserve the average CCT
Figure 3. Spectrum of 5600 K WLEDs with
CaAl2O4:Mn2+
wt
Figure 4. Spectrum of 6600 K WLEDs with
CaAl2O4:Mn2+
wt
Figure 5. Spectrum of 7000 K WLEDs with
CaAl2O4:Mn2+
wt
Figure 6. Spectrum of 7700 K WLEDs with
CaAl2O4:Mn2+
wt
Figure 7. Spectrum of 8500 K WLEDs with
CaAl2O4:Mn2+
wt
This section will illustrate and show the statistical structure of transferred blue lighting and
transformed yellow lighting in the dual-layer phosphorus structure, which can result in a significant
improvement in LED performance [25], [26]. For a single-layer distant phosphorus packet with the thickness
of phosphorus layer set at 2h, the transferred blue lighting and transformed yellow lighting are as shown in
(1) and (2):
(1)
1
2
1 0
B h
PB PB e
5. Bulletin of Electr Eng & Inf ISSN: 2302-9285
Improvement of double-layer phosphor structure WLEDS in color … (Dieu An Nguyen Thi)
2517
(2)
For the double-layer distant phosphor packet, the transferred light of blue and the transformed light
of yellow, with h is the phosphor-layer thickness, are defined as (3), (4):
(3)
(4)
Where h indicates each phosphor-layer thickness. To define the one- and two-layered distant phosphor
packages, the “1” and “2” subscriptions are used. β indicates the transfer factor for the light of blue
transforming to the light of yellow. γ is the backscatter factor of yellow light. The lighting intensity of the
blue LED shown by PB0 is the blue-lighting intensity (PB) and the yellow-lighting intensity (PY). αB and αY
explain the sections of the losing energy of the blue and yellow beams through their spreading of the
phosphorus layer respectively. As compared to a single-layer configuration, the illumination performance of
pc-LEDs with a dual-layer phosphorous configuration is significantly higher:
(5)
In (5) shows that dual-layer distant phosphorus WLEDs have a higher luminescent quality than
single-layer phosphorus WLEDs. Thus, the paper demonstrated the efficacy of the released illuminating
beam of the green-yellow double-layer distant phosphor model. The findings in Figure 8 demonstrate that the
illuminating beam released increases considerably as the CaAl2O4:Mn2+
concentration increases from 2% wt.
to 20% wt. The color variance is greatly decreased with the phosphor CaAl2O4:Mn2+
concentration in all
three average CCTs, according to the findings of Figure 9. These achievements should be attributed to the
green phosphor film’s absorption feature. As the CaAl2O4:Mn2+
phosphor absorbs the light of blue from the
LED chip; these green phosphor particles convert it to the light of green. The CaAl2O4:Mn2+
particles absorb
yellow lighting in addition to the blue lighting from the chip. However, the absorption properties of the
substrate contribute to getting stronger blue light absorption, compared to the other absorption event. As a
result of the inclusion of CaAl2O4:Mn2+
, the green light content in WLEDs increases, resulting in an
improvement in the color uniformity indicator. Color homogeneity is a vital parameter of modern WLED
lamp parameters. Undoubtedly, the better the color homogeneity coefficient, the more expensive WLED
white light. The benefit of using CaAl2O4:Mn2+
is its least expensive application. CaAl2O4:Mn2+
can
therefore be commonly used.
Figure 8. Luminous flux of WLEDs with
CaAl2O4:Mn2+
wt
Figure 9. Color deviation of WLEDs with
CaAl2O4:Mn2+
wt
Color conformity is one of the notable factors to consider when assessing the color consistency of
WLEDs. Yet, color consistency cannot be said to be decent with a high color homogeneity index. Therefore,
recent studies provided an index for color rendering and a scale for color quality. When the color rendering
1 1
2 2
1 0
1
1 1
1
( )
2
Y B
h h
B Y
PB
PY e e
2
2
2 0
B h
PB PB e
2 2
2 2
2 0
2
2 2
1
( )
2
Y B
h h
B Y
PB
PY e e
2 2 1 1
1 1
( ) ( )
0
PB PY PB PY
PB PY
6. ISSN: 2302-9285
Bulletin of Electr Eng & Inf, Vol. 10, No. 5, October 2021 : 2513 – 2519
2518
indicator is illuminated by an illumination, it assesses the real color of a thing. The unbalance of color is
caused by the excessive amount of green light among the three major colors: blue, yellow and green. This
influences the chromatic standard of WLEDs, leading to the decline of color fidelity of a WLED. With the
use of CaAl2O4:Mn2+
remote phosphor layer, the findings in Figure 10 indicate a slight reduction in CRI.
Nonetheless, these are appropriate because CRI is merely a shortcoming in CQS. When drawing a
comparison between CRI and CQS, CQS is more significant and more difficult to accomplish. CQS is a
three-factor indicator that is calculated by three factors: the color rendering index, the viewer's selection, and
color coordinate. For these three important variables, CQS is almost a real total indicator of color
consistency. Figure 11 depicts the enhancement of CQS in the existence of the distant phosphor
CaAl2O4:Mn2+
layer. Moreover, as the concentration of CaAl2O4:Mn2+
is increased, CQS does not change
significantly if the concentration of CaAl2O4:Mn2+
is less than 10% wt. When the CaAl2O4:Mn2+
concentration is higher than 10% wt., both CRI and CQS are greatly decreased due to extreme color loss
when green is predominant. As a consequence, when using green phosphor CaAl2O4:Mn2+
, proper
concentration selection is critical.
Figure 10. Color rendering index of WLEDs with
CaAl2O4:Mn2+
wt
Figure 11. Color quality scale of WLEDs with
CaAl2O4:Mn2+
wt
4. CONCLUSION
The paper represents the influence of CaAl2O4:Mn2+
green phosphorus on the optic characteristics of
the configuration of double-layer phosphorus. The research showed that CaAl2O4:Mn2+
is a suitable choice
for improving color uniformity using Monte Carlo computational simulations. Furthermore, this green
phosphor is applicable not only to WLEDs with low color temperatures, for example 5600 K, but also to
those with a color temperature greater than 7700 K, such as 8500 K in our study. The findings of this analysis
have thus accomplished the objective of enhancing the standard of color and luminous flux, which is very
complicated with the remote configuration of phosphorus. However, one minor disadvantage occurs for CRI
and CQS. When the concentration of CaAl2O4:Mn2+
is increased excessively, either CRI or CQS decrease
significantly. It is therefore necessary to select the proper concentration, based on the objectives of the
manufacturer. In relation to producing greater color uniformity and luminous flux WLEDs, the paper has
given a great amount of essential information for reference.
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