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All Journal TELKOMNIKA (Telecommunication Computing Electronics and Control) Bulletin of Electrical Engineering and Informatics Indonesian Journal of Electrical Engineering and Informatics (IJEEI) Indonesian Journal of Electrical Engineering and Computer Science
Phan Xuan Le
Van Lang University
Computer Science & IT Electrical & Electronics Engineering

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Journal : Bulletin of Electrical Engineering and Informatics

 1 
Improving the optical efficiency of white light-emitting diodes based on phosphor-in-glass by a dual-layer remote phosphorus structure with the application of LiLaO2:Eu3+ and CaSO4:Ce3+, Mn2+ Phan Xuan Le; Le Tien
Bulletin of Electrical Engineering and Informatics Vol 10, No 4: August 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v10i4.2904

Abstract

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.
Effects of NaB2O4:Mn2+ and Ba2Li2Si2O7:Sn3+,Mn2+ phosphors and remote structure organizations on the white light-emitting diodes with quantum dots and phosphors Phan Xuan Le; Le Nguyen Hoa Binh
Bulletin of Electrical Engineering and Informatics Vol 10, No 4: August 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v10i4.3083

Abstract

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.
Triple-layer remote phosphor structure: a selection of the higher color quality and lumen efficiency for WLEDs Phan Xuan Le; Le Hung Tien
Bulletin of Electrical Engineering and Informatics Vol 10, No 4: August 2021
Publisher : Institute of Advanced Engineering and Science

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

Abstract

To enhance color quality of glass-based phosphor-converted white light-emitting diodes (pc-WLEDs) with multi-layer remote phosphor layer structures, two phosphors, green CdS:In and red ZnS:Te,Mn, are integrated into the glass matrix and applied to the dual-layer and triple-layer WLED packages. The attained results were examined with Mie-scattering theory and Lambert-Beer law. The dual-layer showed significant enhancement in color rendering index (CRI), in the range of approximate 80-90. Meanwhile, CRI in the triple-layer was lower and stayed around 66. In terms of color quality scale (CQS), a more overall color evaluating index, triple-layer structure helps the glass-based WLED achieve higher value than the dual-layer. The triple-layer is also beneficial to the luminous efficacy, according to the experimented results. Thus, the triple-layer structure can be used to strengthen the benefit of the glass matrix used in WLED products.
Applying SiO2 nano-particles for improving optical properties of WLED conformal and in-cup structures Phan Xuan Le; Pham Quang Minh
Bulletin of Electrical Engineering and Informatics Vol 10, No 4: August 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v10i4.3085

Abstract

This article is the analysis of SiO2 nano-particles’ influences on the luminous efficiency and the color temperature uniformity of a remote phosphor structure in a WLED. The purpose of integrating SiO2 into the silicone layer in the remote phosphor structure is to significantly promote the scattering occurrences. Particularly, with an appropriate proportion of SiO2, there could be more blue lights generated at large angles, leading to reducing the angular-dependent color temperature deviation. The luminous flux also can get benefits from SiO2 addition owing to a proper air-phosphor layer refractive index ratio provided by this SiO2/silicone compound. The attained experimental results were compared with optical values of a non-SiO2 remote phosphor configuration and showed a notable enhancement. The color deviation was reduced by approximately 600 K in the angles from -700 ­to 700. Additionally, the lumen efficiency was improved by 2.25% at 120 mA driving current. Hence, SiO2 can be used to boost both color uniformity and luminous efficacy for remote-phosphor WLED.
(Y,Gd)BO3:Eu red phosphor for dual-layer phosphor structure to enhance the optical performance of white light-emitting diodes Phan Xuan Le; Le Hung Tien
Bulletin of Electrical Engineering and Informatics Vol 10, No 4: August 2021
Publisher : Institute of Advanced Engineering and Science

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

Abstract

Among the structures using for fabricating white light-emitting diodes (WLEDs) such as the conformal coating or in-cup geometries, the remote phosphor structure gives the highest luminous efficacy. However, in terms of color quality, its performance is not as good as the others. The red-light compensation has been reported as the effective solution for enhancing the color quality of WLEDs. Hence, this study adopted the idea and applied to the dual-layer phosphor structure. The phosphor used to boost the red color in light formation is (Y,Gd)BO3:Eu particle. The dual-layer remote phosphor structure was simulated with the red (Y,Gd)BO3:Eu phosphor layer above the original yellow phosphor YAG:Ce3+ one. The WLEDs with different correlated color temperatures of 5600 K, 6600 K and 7700K were experimented. Mie-theory and Lambert-Beer law were applied to examine the results. The growth in color rendering index (CRI) and color quality scale (CQS) with the increase of (Y,Gd)BO3:Eu phosphor concentration was observed. Nevertheless, the lumen efficacy would be degraded if the concentration was over a certain number. The information provided in this article is useful for the development of high-power WLED production with greater color quality.
The effects of silica-coated Y2O2S:Eu3+ red phosphor on the lighting properties of the light-emitting diode Phuc Dang Huu; Phan Xuan Le
Bulletin of Electrical Engineering and Informatics Vol 11, No 4: August 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i4.4063

Abstract

The red phosphor Y2O2S:Eu3+ coated with silica (SiO2) nanocomposite was synthesized using the sol-gel method with dip-coating technique. The purpose of coating the poly (methyl methacrylate) (PMMA)-SiO2 composite on Y2O2S:Eu3+ phosphor’s surface is to protect the phosphor and improve its scattering ability. The three primary ingredients of coating composition include methyl methacrylate (MMA) monomer, tetraethyl orthosilicate (TEOS), and SiO2 nanoparticles. Via Mie scattering theory, the scattering of SiO2 is examined, which primarily determines the scattering of PMMA-SiO2-coated Y2O2S:Eu3+. The larger particles of SiO2 in the coating composite leads to better scattering properties. When being applied in the dual-film remote phosphor configuration of a LED, SiO2@Y2O2S:Eu3+ considerably enhances the CRI and the color quality scale (CQS). The highest CRI and CQS can be observed at approximately 85 and 74 with 23 %wt. and 26 %wt. the concentration of SiO2@Y2O2S:Eu3+, respectively. Neverthless, the illuminating beam of the package gradually declines as the concentration of SiO2@Y2O2S:Eu3+ go up, which might be ascribed to excessive scattering occurrences in the double-layer remote package.
Study of ZnS:Mn2+,Te2+ phosphor for improving the hue rendering indicator of WLEDs Van Liem Bui; Nguyen Thi Phuong Loan; Phan Xuan Le
Bulletin of Electrical Engineering and Informatics Vol 11, No 4: August 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i4.4061

Abstract

This research combines a phosphor-in-glass (PiG) YAG:Ce3+ with a red liquid-type quantum dot (LQD) to invent high-quality white light-emitting diodes (WLEDs). When the PiG LQD-built WLEDs reach 100 mA, they provide heated white illumination offering an outstanding color rendering index (CRI) (Ra=93.9, R9=97.7, and R13=98.1). The luminescent efficiency (LE) and correlating chromatic temperature, correspondingly, are 62 lm/W and 3764 K. In comparison to PiG integrated with solid-kind quantum dot, it has great LE, remarkable CRI, and lower top layer temperature because of self-aggregation and impediment in the outside flaws in semiconductor quantum dots (QDs) of the solid-condition, as well as effective thermal dissipation. The findings suggest that the produced WLEDs could be potential in high-quality lighting applications.
The qualities of dyed YAG:Ce3+@SiO2 for WLEDs via energy conversion Phung Ton That; Phan Xuan Le
Bulletin of Electrical Engineering and Informatics Vol 11, No 5: October 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i5.4064

Abstract

Y3Al5O12:Ce3+ (YAG:Ce3+), the most common yellow phosphor for WLEDs, has a red insufficiency in its light spectrum. The Ce3+ spectral profile is modified in this research using surface-located ATTO-Rho101 dye molecules, which have powerful, wide impregnation in the greenish-yellow spectroscopic zone of Ce3+ radiation and vivid red-emitting radiation. To create a spherical shell and evenly dispersed micro and nanometer YAG:Ce3+, a modified solvothermal technique is applied. Surface SiO2 covering and synchronized dye embedding are accomplished using solvothermally generated YAG:Ce3+, temperature-stimulated micro-YAG:Ce3+, plus commercialized phosphorus. Upon blue light excitation, the accumulated YAG:Ce3+@SiO2+dye powder exhibits efficient radiative conversion/reintake from Ce3+ within the internal structure of YAG to the pigment particles from the SiO2 external shell, despite the phosphors' diameter; which likely boosts its red radiation. Fluorescence microscopy would be a suitable way to determine the reabsorption of powdered substances.
The color-adjustable phosphor Sr4La(PO4)3O:Ce3+,Tb3+,Mn2+ of WLEDs: luminescence and transfer of energy characteristics Phuc Dang Huu; Phan Xuan Le
Bulletin of Electrical Engineering and Informatics Vol 11, No 5: October 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i5.4062

Abstract

A high heat solid-state technique was used to produce a set of phosphor Sr4La(PO4)3O:Ce3+,Tb3+,Mn2+ (Sr:Mn). In Sr4La(PO4)3O, the luminescence characteristics, heat resistance, and energy conversion between Ce3+ and Tb3+ as well as Mn2+ were thoroughly researched. Introducing the activator Ce3+ particles can significantly increase the dim green-emitting from Tb3+ and the red-emitting from Mn via energy conversion. The color of the emissions might be changed by adjusting the Ce3+/Tb3+ and Ce3+/Mn2+ ion ratios. In the Sr4La(PO4)3O: 0.12 Ce3+,0.3 Mnz2+ specimen, we achieved white-emitting illumination, yielding hue coefficients (0.3326, 0.3298), showing that the phosphor Sr:Mn could have promising implications for white light-emitting diodes (WLEDs).
Co-Authors Dieu An Nguyen Thi Dieu An Nguyen Thi Dieu An Nguyen Thi Dieu An Nguyen Thi Le Hung Tien Le Nguyen Hoa Binh Le Tien My Hanh Nguyen Thi Nguyen Doan Quoc Anh Nguyen Le Thai Nguyen Thi Phuong Loan Pham Quang Minh Phuc Dang Huu Phuc Dang Huu Phuc Dang Huu Phung Ton That Phung Ton That Phung Ton That Thanh Binh Ly Tran Thanh Trang Van Liem Bui Van Liem Bui