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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
Phung Ton That
Industrial University of Ho Chi Minh City
Computer Science & IT Electrical & Electronics Engineering

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Journal : Indonesian Journal of Electrical Engineering and Computer Science

 1 
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.
The enhancement of the dual-layer phosphorus configuration in color uniformity and luminous flux of a light emitting diode Phuc Dang Huu; 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.pp766-772

Abstract

A solid-state process was used to generate the green phosphor Ca3Si2O4N2:Eu2+. The luminescence characteristics, dispersed reflection spectra, and heat quenching were investigated initially, followed by the white light emitting diodes (wLED’s) manufacture by the Eu2+ stimulated Ca3Si2O4N2 phosphor. Based on the concentration of ion Eu2+, a wide green emission range localized between 510 and 550 nm was seen in Eu2+ -doped Ca3Si2O4N2. In Ca3Si2O4N2, the best doping concentration of Eu2+ was 1 mol%. An electric multipolar interaction process conveys energy among Eu2+ ions, with a necessary conversion distance of around 30.08 Å. Blending a near-ultraviolet (n-UV) light emitting diodes (LED) which has a GaN basis (380 nm) with the blue BaMgAl10O17:Eu2+, the green  Ca3Si2O4N2:Eu2+, and the red Ca3Si2O4N2:Eu2+ phosphors yielded a wLED with a 88.25 color-rendering indice Ra at 6029 K correlating color temperature.  Ca3Si2O4N2:Eu2+ appears to be a promising option to apply as a converting phosphor in wLED applications.
Ca9La(PO4)7:Eu2+,Mn2+: a radiation-adjustable phosphor usable for high-perfomance white light-emitting diodes Phuc Dang Huu; Phung Ton That; Phan Xuan Le; Nguyen Le Thai
Indonesian Journal of Electrical Engineering and Computer Science Vol 27, No 3: September 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v27.i3.pp1290-1296

Abstract

We used solid-condition processes to make a sequence of radiation-adjustable phosphors Eu2+/Mn2+ co-doped Ca9La(PO4)7 (shortened as CaLa:EM), which show a consistently variable hue from green to yellow and red via an efficient resonance-form energy transition as well as the strength of green and red radiations may be controllable through altering the Mn2+concentration. We examined the transition of energy (Eu2+®Mn2+) for CaLa:EM. It is proved to be a resonant kind using a dipole-quadrupole process, having power shift critical range calculated to be 11.36 Å by using the spectral overlap techniques. Mixing a 365 nm UV-InGaN chip as well as one phosphor combination containing (Ca0.98Eu0.005Mn0.015)9La(PO4)7 in yellow with BaMgAl10O17:Eu2+in blue produced a warming WLED having CIE color coordinates measured at (0.35, 0.31), better CRI value (Ra)measured at 91.5 along with smaller CCT value of 4,496 K.
Ca8MgY(PO4)7:Eu2+,Mn2+ for better angular chromatic harmony and high lumen for white diode Phuc Dang Huu; Phung Ton That; Phan Xuan Le; Nguyen Le Thai
Indonesian Journal of Electrical Engineering and Computer Science Vol 27, No 3: September 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v27.i3.pp1297-1303

Abstract

The multifunctional phosphor Ca8MgY(PO4)7doping with Eu2+ and Mn2+ ions (CaMn) is utilized to stimulate the rate of light extraction and color harmony of the white light-emitting diode (WLED) package using remote phosphor design with two sheets of phosphor. The CaMn sheet helps to reduce the color variation and light scattering backward mainly caused by high concentration of yellow phosphor YAG:Ce3+ film. The experimental results show a gradual increase of luminous flux and significant reduction of chromatic deviation in direct proportion to the increasing concentration of CaMn phosphor. Meanwhile, with more than 9% wt of CaMn concentration, the reduction of color rendering properties is presented because of the redundant green emission, leading to the lack of blue and yellow emission energies. Good color quality scale that peaks at 63 can be achieved with 2-4%wt. CaMn in the WLED packages. It is advisable to manage the concentration the green phosphor CaMn to attain desirable optical objectives.
Enhancement of the lighting quality for white light-emitting diodes with CaSc2O4:Ce3+ phosphor Phuc Dang Huu; Phung Ton That; Phan Xuan Le; Nguyen Le Thai
Indonesian Journal of Electrical Engineering and Computer Science Vol 27, No 3: September 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v27.i3.pp1282-1289

Abstract

For the task of realizing greater progress for the light output in white light-emitting diodes (WLEDs), this study focuses on the luminescence temperature subordination feature of CaSc2O4:Ce3+ phosphor (abbreviated to CaS for this study). Some other aspects of the phosphor were also included in this piece of paper: Huang-Rhys coupling factor, Stokes shift, triggering power, abatement temperature and especially, abatement behavior in CaSc2O4:Ce3+. Creating the bluish-green LEDs by the combination of blue InGaN chip and CaSc2O4:Ce3+ is the primary purpose. CaSc2O4:Ce3+ appears to be a decent green phosphor that can be used in WLEDs made of blue InGaN chip. Production tasks may be based on our investigation for the task of making desirable WLED devices that meet the production demands.
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