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All Journal International Journal of Electrical and Computer Engineering TELKOMNIKA (Telecommunication Computing Electronics and Control) Bulletin of Electrical Engineering and Informatics Indonesian Journal of Electrical Engineering and Computer Science
My Hanh Nguyen Thi
Industrial University of Ho Chi Minh City
Computer Science & IT Electrical & Electronics Engineering

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Journal : International Journal of Electrical and Computer Engineering

 1 
Using CaCO3-doped package to improve correlated color temperature uniformity of white light-emitting diodes My Hanh Nguyen Thi; Nguyen Thi Phuong Loan; Thuc Minh Bui; Hoang Van Ngoc
International Journal of Electrical and Computer Engineering (IJECE) Vol 11, No 6: December 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v11i6.pp4817-4824

Abstract

The white light-emitting diode (WLED) has been the most advance lighting method currently, however, the fabrication process of this configuration still has drawbacks which negatively affect its color quality. This research was conducted to provide a method for WLED’s lighting output enhancement. Since CaCO3 particles are excellent for thermal stability enhancement, especially when being combined with an adhesive substance, we decided to integrate CO3 particles into resin matrix such as melamine formaldehyde (MF) and investigate their influences on the optical properties, including color uniformity and lumen output, of the WLED. The results showed that CaCO3 and MF resin are beneficial to the light scattering efficiency, which results in higher luminous flux and chromatic quality for WLED packages. In addition to that, the appropriate amounts of MF resin and CaCO3 for reaching the best lumen efficiency and color quality are figured out at 1% and 10%, respectively. Moreover, another advantage of using MF resin and CaCO3 for fabricating WLEDs is cost effectiveness. Hence, it has turned out that CaCO3 and MF resins can be potential materials for next high-quality WLED generations.
Aiming to the superior of phosphor pattern: Influence of SiO2 nanoparticles on photoluminescence intensification of YAG:Ce My Hanh Nguyen Thi; Thuc Minh Bui; Nguyen Doan Quoc Anh
International Journal of Electrical and Computer Engineering (IJECE) Vol 11, No 6: December 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v11i6.pp4833-4839

Abstract

Yttrium aluminum garnet (YAG: RE) rare-earth-doped phosphors have great photoluminescence (PL) characteristics and are commonly used in light-emitting rectifying tubes. The RE elements used in these phosphors, however, are precious and in shortage. The production of phosphorus containing a limited amount of RE content is therefore essential. One solution is to manufacture Nano composite phosphors that use an inexpensive and more easily available content as a matrix for RE oxide. In this research, we developed a YAG: Ce/SiO2 Nano composite using a sol-gel procedure; in order to impulse micelle formation and agglomeration, poly (ethylene glycol) and urea have been added, respectively. X-ray diffraction, scanning and transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy were used to characterize the Nano composites. In proposing an explanation for this enhancement, we defined the concentration of SiO2 that produced optimum PL enhancement and used geometric models as well as the characterization consequences. Our results demonstrated that a 10% SiO2 concentration produced a 120% PL intensity of pure YAG:Ce. TEM analysis revealed that SiO2 nanoparticles filled the voids between the YAG:Ce crystals' single grain borders, hence inhibiting light scattering, resulting in increased PL. This procedure would be beneficial for the synthesis of low-RE and high-PL phosphors on a wide scale.
The effect green YF3:ER3+,YB3+ phosphor on luminous flux and color quality of multi-chip white light-emitting diodes My Hanh Nguyen Thi; Nguyen Thi Phuong Loan; Thuc Minh Bui; Anh Tuan Le
International Journal of Electrical and Computer Engineering (IJECE) Vol 11, No 6: December 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v11i6.pp4810-4816

Abstract

The purpose of this paper is to demonstrate the advantages of the green phosphor YF3:Er3+,Yb3+ combined with multi-chip package to the enhancement of lighting efficiency of modern WLEDs. In an effort to improve the quality of WLEDs and create a new generation of lighting device, green phosphor YF3:Er3+,Yb3+ is added into the phosphor compounding of the WLED package to improve the color quality and lighting capacity. Through experiments, WLEDs with YF3:Er3+,Yb3+ green phosphor has shown improved results in lighting performance specifically in color homogeneity and light output of WLEDs in the ACCT range from 5600-7000 K. However, the color quality scale (CQS) declines gradually. Therefore, if the appropriate concentration and size of YF3:Er3+,Yb3+ are determined, the performance of MCW-LEDs will be enhanced and become more stable.
Using SiO2 nano-particles for better color uniformity and lumen output in 8500 K conformal and in-cup white LEDs My Hanh Nguyen Thi; Nguyen Thi Phuong Loan; Thuc Minh Bui; Tri-Vien Vu
International Journal of Electrical and Computer Engineering (IJECE) Vol 11, No 5: October 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v11i5.pp3897-3902

Abstract

In the effort of improving the performance of white light LEDs devices (WLEDs), the SiO2 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 SiO2 particles and silicone gel is diffused on the encapsulation layer surface. This enhancement is the result of light scattering from SiO2 that strengthens the emitted blue light at further angles and reduces the color discrepancy. The evidence is that CCT deviation in SiO2-doped structure decline from 1000 K to 420 K in -70° to 70°. In addition, the SiO2 with refractive index in between the phosphor material and outside environment allows light to be emitted outward more effectively. This lighting enhancement of SiO2-doped structure increases the lumen output by 2.25% at 120 mA power source in comparison to structure without SiO2. These experimental outcomes suggest that SiO2 is an effective material to add in WLEDs structure for better lighting efficiency.
Quantum dot phosphors CaS:Ce3+ and CaS:Pb2+, Mn2+ for improvements of white light-emitting diodes optic characteristics Dieu An Nguyen Thi; My Hanh Nguyen Thi; Phuc Dang Huu
International Journal of Electrical and Computer Engineering (IJECE) Vol 12, No 5: October 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v12i5.pp4782-4789

Abstract

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.
Triple-layer remote phosphor geometry: an excellent selection to improve the optical properties of white light-emitted diodes Thuc Minh Bui; My Hanh Nguyen Thi; Nguyen Doan Quoc Anh; Nguyen Le Thai
International Journal of Electrical and Computer Engineering (IJECE) Vol 13, No 5: October 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v13i5.pp5118-5125

Abstract

High performance white-light-emitting diodes (WLEDs) have been the goal of recent research on phosphor-in-glass (PiG) devices. In this paper, we introduce a configuration of WLED that achieves high color rendering index (CRI), and correlated color temperature with the addition of Zn2SiO4:Mn2+, As5+ and YAl3O4B12:Eu3+. The technique is lower the temperature during the creation process of phosphor in glass and control the consistent thickness in between 0.5 to 0.7 mm to yield high color quality PiG, high CRI above 80 WLEDs, and extend the color temperature range to 3,900 to 5,300 K. The consistent heat generation combined with extraordinary CRI for PiG prove that low temperature sintering has the potential to create WLEDs with advanced quality. The improved WLEDs can be utilized in many high-demand lighting fields such as chromatic examination, medical analysis, and aesthetic lighting.
BaAl1.4Si0.6O3.4N0.6:Eu2+ green phosphors’ application for improving luminous performance My Hanh Nguyen Thi; Nguyen Le Thai; Thuc Minh Bui; Tam Nguyen Kieu
International Journal of Electrical and Computer Engineering (IJECE) Vol 13, No 5: October 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijece.v13i5.pp4958-4965

Abstract

The molten salt synthesis (MSS) method was used to effectively prepare green phosphors BaAl1.4Si0.6O3.4N0.6:Eu2+ (or BSON:Eu2+) via one homogeneous sphere-like morphology utilizing NaNO3 in the form of the reacting agent. The phosphors produced one wide stimulation spectrum between 250 and 460 nm, as well as a significant green emission has a maximum point at 510 nm owing to the 4f65d1-4f7 (8S7/2) shifts for Eu2+ ions. With illumination under 365 as well as 450 nm, the ideal discharge strengths for the specimen prepared utilizing melted salt would receive a boost of 17% and 13%, surpassing the specimen prepared utilizing the traditional solid-state reaction (SSR) approach. The abatement of concentration for the ions of Eu2+ from BSON:Eu2+ is 5 mol%. In addition, the interactivity of dipole-dipole would be the cause of said abatement. Heat abatement would be studied utilizing the formation coordinate method with abatement temperature reaching ∼200 oC. Elemental mapping as well as power-dispersing X-ray spectroscopy (EDS) spectra demonstrated that the expected BaAl1.4Si0.6O3.4N0.6:Eu2+ materials were formed.
Co-Authors Anh Tuan Le Dieu An Nguyen Thi Ha Thanh Tung Ho Minh Trung Hoang Van Ngoc Nguyen Doan Quoc Anh Nguyen Doan Quoc Anh Nguyen Doan Quoc Anh Nguyen Le Thai Nguyen Thi Phuong Loan Phan Xuan Le Phuc Dang Huu Phung Ton That Tam Nguyen Kieu Thuc Minh Bui Tri-Vien Vu Tri-Vien Vu