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All Journal International Journal of Electrical and Computer Engineering Perfecting a Video Game with Game Metrics Bulletin of Electrical Engineering and Informatics Indonesian Journal of Electrical Engineering and Computer Science
Phung Ton That
Industrial University of Ho Chi Minh City
Computer Science & IT Electrical & Electronics Engineering

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Enhancement of luminous flux and color quality of white light-emitting diodes by using green (Y,Gd)BO3:Tb3+ phosphor My Hanh Nguyen Thi; Phung Ton That; Nguyen Doan Quoc Anh
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 3: June 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i3.15746

Abstract

In the study, we analyzed and clarified the effect of green (Y,Gd)BO3:Tb3+ phosphor on chromatic homogeneity and optical performance of multi-chip white LEDs (MCW-LED). Thereby there is a solution to get the best luminous efficiency. In addition, (Y,Gd)BO3:Tb3+ is known as one of the factors that has a significant impact on lighting performance, so it needs to add the (Y,Gd)BO3:Tb3+ phosphor in the structure of LEDs to combine with the yellow phosphor YAG:Ce3+ to receive the best results. Therefore, the concentration and size of (Y,Gd)BO3:Tb3+ should be choose carefully so that the presentation of MCW-LEDs would be more incredible. The results show that when the concentration of green-emitting (Y,Gd)BO3:Tb3+ phosphor tends to increase, it also helps the color homogeneity and the lumen efficiency of MCW-LEDs with the average correlated color temperature (CCT) of 5600 K-8500 K become better.
MgCeAl11O19:Tb3+ and Mg8Ge2O11F2:Mn4+ in enhancing the color quality of remote phosphor LED My Hanh Nguyen Thi; Phung Ton That
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 3: June 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i3.14479

Abstract

As the name infers, the triple-layer remote phosphor (TRP) has 3 phosphor layers includes the red Mg8Ge2O11F2:Mn4+ phosphor layer on the top, the green MgCeAl11O19:Tb3+ phosphor layer in the middle, and the yellow YAG:Ce3+ layer at the bottom and is mentioned as a solution to increase the chromaticity and luminescence adequacy of the white LEDs (WLEDs) in this article. As to control the red light for higher value achieve in the color rendering index (CRI), using red Mg8Ge2O11F2:Mn4+ phosphor in the TRP structure is recommended. All the outcomes indicate that when red phosphor Mg8Ge2O11F2:Mn4+ concentration grows the CRI gets higher values, and drastically declines when the concentration of green phosphor MgCeAl11O19:Tb3+ increases. As the same time, applying the green MgCeAl11O19:Tb3+ phosphor layer to manage the green light as it can make the luminous efficacy (LE) of WLEDs increase. In particular, the index of LE can also be improved over 40% by limiting the scatter of light and putting in green light. Moreover, to preserve the average correlated color temperature (ACCT) stable at 8500K, the yellow YAG:Ce3+ concentration must be cut down as the concentration of red and green phosphor rise.
Green Ca2La2BO6.5:Pb2+ phosphor: an innovative solution in enhancing the color quality and luminous flux of WLEDs Phung Ton That; Nguyễn Đoàn Quốc Anh
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 5: October 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i5.14672

Abstract

Light-emitting diodes devices that embedded with multiple chips (multi-chip white LEDs (MCW-LEDs)) are an advanced lighitng solution with much potential for improvement in the lighting industry. However, to further the applicacations and quality of white light emitting diodes (WLEDs) greater achivements must be found, thus, this paper focus on improving the color uniformity and luminous flux with green phosphor Ca2La2BO6.5:Pb2+. The results, which were measured through experiments conducted in WLEDs with average correlated color temperature from 6600–7700 K, show enhancements in color uniformity and luminous efficacy. In particular, the growing trend in the concentration of green phosphor Ca2La2BO6.5:Pb2+ results better color uniformity and lumnous flux, although the color quality scale (CQS) suffers a small decline. Therefore, it is confirmed that the Ca2La2BO6.5:Pb2+ phosphor is suitable in manufacturing WLEDs that focus on the color uniformity and luminous flux.
Integrating SiO2 nanoparticles to achieve color uniformity and luminous efficiency enhancement for white light emitting diodes Phan Xuan Le; Phung Ton That
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 5: October 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i5.20484

Abstract

A phosphor structure with SiO2 nanoparticles is proposed to achieve the enhancement in the correlated color temperature (CCT) homogeneity and the luminescence performance for white light-emitting diodes (WLEDs). As SiO2 is integrated into the phosphorus compound, the scattering effect of this material contributes to better blue-light utilization. Thus, this innovative packaging design results in a significant increased lumen efficiency, more than 12%, in comparison with that of conventional dispensing ones. Meanwhile, the angular CCT deviation also decreases considerably, from 522 K to 7 K, between the angles of -70 and 700. Moreover, this reduction leads to the diminishment of yellow ring phenomenon effect. In addition, the measurement of haze demonstrates that there is a strong scattering in the visible spectrum when SiO2 is added into the silicone film. Besides that, when increasing the driving current, SiO2 stabilizes the chromaticity coordinate shift, which is a vital requirement for indoor lighting applications. Furthermore, SiO2 nanoparticles own excellent optical features, cost efficiency, and simple production will probably turn this material into a potential material in advancing the optical performance of WLEDs.
The analysis of MF resin and CaCO3 diffuser-loaded encapsulations to enhance the homogeneity of correlated color temperature for phosphor-converted LEDs My Hanh Nguyen Thi; Phung Ton That
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 2: April 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i2.16519

Abstract

The most popular method used in the production of phosphor-converted LEDs (pc-LEDs) is dispensing phosphor freely. However, this method is inferior in generating good angular correlated color temperature (CCT) homogeneity. Thus, in this article, a diffuser-loaded encapsulation is proposed as a potential solution for better CCT uniformity. The paper provides a detailed investigation on how melamine formaldehyde (MF) resin and CaCO3 loaded encapsulations impact the uniformity of CCT, as well as the lumen efficacy of pc-LEDs. The results demonstrate that between MF resin and CaCO3 loaded encapsulations, the MF resin yields a higher light diffusion efficiency while the CaCO3 maintains greater lumen efficacy. The photon scattering development is the key force behind the enhancement of the angular CCT uniformity in pc-LEDs’ output when using the loaded encapsulations of MF resin and CaCO3 particles. Since this package utilized mineral, it has reasonable cost and is quite easy to control while still being effective in enhancing the angular CCT homogeneity of pc-LEDs. Diffusers with 1% concentration of MF resin or 10% concentration of CaCO3 are determined as an optimal solution for reducing the variance of angular CCT and increasing the lumen output.
The impacts of red-emitting phosphor Mg8Ge2O11F2:Mn4+ on the color rendering index of convex-dual-layer remote phosphor WLEDs at 5600 K My Hanh Nguyen Thi; Phung Ton That; Nguyen Doan Quoc Anh
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 3: June 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i3.15832

Abstract

The poor color rendering index (CRI) induced by mono chip and phosphor configuration in the conventional white-light light-emitting diode (LED) urges for developments in both packaging and material, thus, a modern lighting solution was introduced. The dual-layer phosphor package is an innovative configuration that can retain the lumen output of conventional white light emitting diode (WLED) while also enhancing color quality. The structure of dual-layer phosphor package that was proposed includes two chips and one phosphor. The priority in this research is to keep improving the lighting properties of WLED, therefore, further experiments with this dual-chips and dual-phosphor package are conducted. The lighting properties of LED are measured multiple times with its nitride-based phosphor being altered in proportions and densities each occasion, the results are calculated with a color design model made specifically to monitor and adjust the color of white-light from LED to match desired outcome. The WLED at 5600 K correlated color temperature (CCT) is the sole research object of the experiments. The measured parameters from the 5600 K WLED and the color coordinates of CIE 1931 simulated from the color design model show that 0.0063 is the highest possible discrepancy at 5600 K (CCT). The information from this manuscript provide the manufacturers with the most efficient approach to create a white LED that has good color quality, high CRI and luminous flux.
Improvement of double-layer phosphor structure WLEDS in color homogeneity and luminous flux Dieu An Nguyen Thi; Phung Ton That; Hoang Nam Nguyen
Bulletin of Electrical Engineering and Informatics Vol 10, No 5: October 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v10i5.2914

Abstract

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.
Decreasing CCT deviation of white light emitting diodes by employing SiO2 nanoparticles My Hanh Nguyen Thi; Phung Ton That
Bulletin of Electrical Engineering and Informatics Vol 10, No 3: June 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v10i3.3041

Abstract

In this research, the SiO2 nano-particles (NPs) usage in enhancing optical performances of InGaN/GaN-based white light-emitting diodes (WLEDs) with remote phosphor structure. The research subject shows better lighting capacity than the white LEDs devices without the space between the layers. The adjustment in development process resulted in enhancements of internal quantum efficiency (IQE) and light extraction efficiency (LEE) that lead to 13.5% luminous efficacy improvement. From the experiments, it can be concluded that the LEE is affected by the trapped light and enhancing the light output with SiO2 scattering properties reduce the amount of trapped light. These results confirm that SiO2 nano-particles is effective in enhancing the optical performance of WLEDs and can be considered for production of higher quality devices.
Employing SiO2 nano-particles in conformal and in-cup structures of 8500 K white LEDs My Hanh Nguyen Thi; Phung Ton That
Bulletin of Electrical Engineering and Informatics Vol 10, No 3: June 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v10i3.3042

Abstract

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.
Effects of titanium dioxide quantum dots on the color deviation and luminous flux of white light-emitting diodes Thanh Binh Ly; Phung Ton That; Phan Xuan Le
Indonesian Journal of Electrical Engineering and Computer Science Vol 27, No 2: August 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v27.i2.pp611-617

Abstract

The application of quantum dots has been considered as a promising approach to the advancement of phosphor-converted light-emitting diodes (pc-LEDs) since they perform an excellent extinction coefficient. Yet, it is challenging to manage their influences on the optical properties of LEDs due to their different nanometers in size. Hence, the object of this research is to analyze the influences of quantum dot (QDs) to figure out the solution to control the enhancement of LED lighting performances. Particularly, the study worked on investigating the scattering and absorption features of titanium dioxide (TiO2) QDs. It demonstrated that the radiant efficiency and luminous stability of the TiO2 QDs-converted LEDs (QC-LEDs) was inferior due to the strong light absorption and reabsorption occurring inside the LED packages. Additionally, it also presented low uniformity of color distribution because the scattering ability of QDs is weak. Therefore, reducing the concentration of QDs when adding to the LED structure seems to be possible to enhance the luminous output of QC-LEDs. We propose 0.05% wt. TiO2 for white LED to reduce the illumination losing caused by re-absorbent and total internal backscattering, resulting in approximate 31% lumen improvement and high color rendering index (CRI) measured at about 85, at a high color temperature of 7500 K.
Co-Authors Dao Huy Tuan Dieu An Nguyen Thi Duy-Hung Ha Ha Thanh Tung Hoang Nam Nguyen Hoang Van Ngoc Huu Phuc Dang Le Van Tho Miroslav Voznak My Hanh Nguyen Thi Nguyen Doan Quoc Anh Nguyen Le Thai Nguyen Thi Phuong Loan Nguyễn Đoàn Quốc Anh Nhat-Tien Nguyen Phan Xuan Le Phan Xuan Le Phuc Dang Huu Thanh Binh Ly Thuc Minh Bui Tran Thanh Trang Tri-Vien Vu