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Nguyen Le Thai
Nguyen Tat Thanh University
Computer Science & IT Electrical & Electronics Engineering

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Journal : Indonesian Journal of Electrical Engineering and Computer Science

 1 
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.
The impacts from Sr4La(PO4)3O: Ce3+, Tb3+, Mn2+ phosphor resulting in luminous flux of WLED devices Huu Phuc Dang; Bui Van Hien; Nguyen Le Thai
Indonesian Journal of Electrical Engineering and Computer Science Vol 28, No 2: November 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v28.i2.pp693-699

Abstract

Using the solid-state technique that involves great temperature, we created multiple phosphors Sr4La(PO4)3O:Ce3+, Tb3+, Mn2+ (abbreviated as SLPO:Ce, Tb, Mn). We then examined their heat consistency, luminescence, as well as energy shift from Ce3+ to Tb3+ and Mn2+. We can acquire a considerable boost for the faint emission in green generated by Tb3+ as well as the emission in red generated by Mn2+ via adding the sensitizer Ce3+ ions. Through modifying the proportion between Ce3+ and Tb3+ along with the proportion between Ce3+ and Mn2+, it is possible to adjust the chroma of emission. We acquired white illumination which had color coordinates determined as (0.3326, 0.3298) for the testing phosphor Sr4La(PO4)3O: 0.12Ce3+, 0.3Mn2+. Such result displays the promising efficiency of phosphors Sr4La(PO4)3O:Ce3+, Tb3+, Mn2+ for the WLED devices.
Study of phosphor Ba2Si3O8:Eu2+ to produce WLED devices with support from ZnCdSe/ZnSe quantum dot Huu Phuc Dang; Bui Van Hien; Nguyen Le Thai
Indonesian Journal of Electrical Engineering and Computer Science Vol 28, No 2: November 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v28.i2.pp729-734

Abstract

We created the blue-green Ba2Si3O8:Eu2+ (or BaE) phosphor treated with Eu2+ using the standard solid-state method with the concentration of Eu as well as heating temperature properly adjusted for the maximum luminescence efficacy. It is possible to excite the said phosphor using near-UV (n-UV) wavelengths and to display its wide emission band, which is the 5d => 4f shift for Eu2+, caused by the combination of the Eu activator and the nearby host. We integrated the said phosphor with the n-UV LED to create the pc-LED (short for diodes based on conversion phosphor). For the task of creating the WLED device that yields significant color rendering index, we combined the orange ZnCdSe/ZnSe quantum dot with a distinctive sheet structure for the pc-LED made with phosphor BaE. This research demonstrates the electroluminescence features of the said elements.
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.
High stability in color chromaticity of warm white emitting diode with dual-hue SrSi2O2N2:Eu2+,Yb2+ phosphor My Hanh Nguyen Thi; 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.pp1258-1263

Abstract

In this study, we analyzed and developed a phosphor with a nitridiosilicate based and emitting color changing from green to orange to apply to our white-light-emitting diodes (WLEDs). Eu2+ and Yb2+ trap sites of two-doped SrSi2O2N2:Eu2+,Yb2+ (SrYb) nitridosilicate emit a wide emission in the region between green and orange. Through calculating the decompose time of the green-emission power donor, we could determine the converted energy between the active ions. Furthermore, we also analyzed the impact of co-doping with varied active ion ratios on the photoluminescence (PL) characteristics. As the concentration of Yb2+ increases, the red emission dominates the green. This was because the obtained phoshor's emission depended on the activator ion components. To generate white light, a combination of the acquired phosphor and the InGaN blue LED chip with a 450 nm wavelength was used. With only two steps, we could detect the hue balance management. Firstly, by modifying the Eu2+ and Yb2+ concentration, we can conduct a green-to-orange proportion optimization. Following that, the commission onillumination (CIE) coordinates were transformed to [0.4071; 0.3789] from the original position, which was [0.2805; 0.2014] by enhancing the phosphor powder amount. An environment which has a CRI of around 89 is the optimum condition for conducting white light.
The application of multi-layer phosphor-in-glass sheets in boosting white light emitting diodes chromaticity Ha Thanh Tung; Huu Phuc Dang; Nguyen Le Thai
Indonesian Journal of Electrical Engineering and Computer Science Vol 29, No 3: March 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v29.i3.pp1318-1325

Abstract

With the use of phosphor-in-glass (abbreviated as PiG), it is possible to make alterations for the remote adjustment incorporated with a diode that generates blue light emitting diode (LED) and acquire remarkably superior light output at considerable temperatures of color compared to standard structures of LED devices. It should be noted that the imbrication of emission spectra in phosphor substances, as well as the forfeited, amount of light caused by reabsorption appear to be the primary problems stemming from the model of multi-color phosphor. The earlier study came up with the method of creating various phosphor-in-glass (PiGs) by slicing and reconstruction, which remedied certain aspects of the flaws mentioned. Practically speaking, the light amount forfeited occurs in the linking zones in the middle of the color phosphor and will be a subject of the research. We can see for certain that it is necessary to come up with a means of preparation to deal with the issues of the interfacial layer. Therefore, the low sintering of PiGs at 600 °C was considered an appropriate procedure, as it could create a double-layer PiG in a lying direction as well as a triple-layer PiG yielding superior optical efficiency when compared to equivalent versions.
Hue dual-chromatic calcium chlorosilicate phosphor for light-emitting diode having yellow and white illumination Huu Phuc Dang; Bui Van Hien; Nguyen Le Thai
Indonesian Journal of Electrical Engineering and Computer Science Vol 28, No 2: November 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v28.i2.pp724-728

Abstract

High-thermal solid phase reactions produced a series of bright green-yellow phosphors called Ca3SiO4Cl2,Eu2+,Mn2+ (CaM). For example, powder dispersed reflection, photoluminescence excitation (PE), and along with emission spectra, were used to determine their luminous characteristics at between 10 K and 450 K of temperature. While the CaM exhibits wide absorption bands in the 250-450 nm range, which matches the near-uv of the InGaN-based chips, they also display two dominant absorptions, attributed to the 5d → 4f Eu2+ transformation, as well as the 4T1g(4G) → 6A1g(6S) transfer of the two ions Eu2+ and Mn2+, respectively. Increasing the concentration of Mn2+ ion reduces the lifespan of the Eu2+ ion. This encourages an efficient energy exchange between these two ions. The UV light leakage issue in yellow LEDs was resolved by intergrating with n-UV InGaN chips and CaM. Powerful white LEDs were then created by mixing blue chlorophosphate with CaM. Its color coordinate was (0.3281,0.3071), and the associated color temperature (TC) was 6065 K, while the general hue rendering (Ra) and illuminating effectiveness (11 lm/W) were respectively 84.5 and 11 lm/W.
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.
Green-phosphor Ca3Sc2Si3O12:Ce3+ for solid-status illumination: gel-combustion structural and luminous characteristics Huu Phuc Dang; Bui Van Hie; Nguyen Le Thai
Indonesian Journal of Electrical Engineering and Computer Science Vol 28, No 2: November 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v28.i2.pp710-715

Abstract

Ca3Sc2Si3O12:Ce3+ phosphors with one stage and tiny dimension were effectively produced utilizing the gel-combustion technique at a lower heat (1100◦C) than the traditional solid-status reaction technique (around 1500◦C). The phosphors' crystal phase and microstructure, as well as their luminescence, were studied. The particle size is around 1m, which is significantly smaller than what the solid-status process produces. When particles are combined of silicon and deposited on a blue light-emitting diode (LED), finer particles can minimize interior diffusing. A significant green radiation is noticed that is caused by typical Ce3+ transition radiations 5d–2F5/2 and 5d–2F7/2. The stimulation spectra reveal a wide and high absorptivity at around 460 nm, indicating that it would be an excellent color conversion in white LEDs. The gel-combustion phosphor has a decay period of 54.65 ns.
Effects of Pr3+ -activated BaZrGe3O9@TiO2 phosphor compound on light emitting diodes validated by computer simulation Le Thi Trang; Le Xuan Thuy; Nguyen Le Thai; Thuc Minh Bui
Indonesian Journal of Electrical Engineering and Computer Science Vol 34, No 3: June 2024
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v34.i3.pp1482-1488

Abstract

The Pr3+ -doped BaZrGe39 gallogermanate phosphors are reported to have a well-defined successive deep defect structure that effectively mitigates thermal carrier fading. This phosphor also presents a red emission with a peak at 615 nm, originating from the Pr3+ transtition from 1D2 to 3H4. We investigated the impact of Pr3+ -activated BaZrGe3O9 (referred to as BZG:Pr) on the lighting characteristics of light emitting diodes (LED) packages in this paper. By combining BZG:Pr with TiO2 particles and silicone, we produced a phosphor layer (designated as BZG:Pr@TiO2). The optical performance of the resulting LED was systematically examined by varying the TiO2 doping percentage. Our findings reveal that the incorporation of the BZG:Pr phosphor enhances the red spectral component, thereby contributing to improved homogeneity in color distribution. However, a progressive increase in TiO2 content within the phosphor layer corresponds to diminishing luminous output and decreased chromatic rendering efficiency of the LED. Employing a lower concentration of TiO2 proves advantageous, as it capitalizes on the scattering-enhancing attributes while leveraging the red emission of the BZG:Pr phosphor. This synergistic approach yields a favorable balance between luminosity and color quality, enhancing the LED’s overall performance.
Co-Authors Bui Van Hie Bui Van Hien Ha Thanh Tung Huu Phuc Dang Huu Phuc Dang Huu Phuc Dang Le Thi Trang Le Xuan Thuy My Hanh Nguyen Thi Nguyen Doan Quoc Anh Phan Xuan Le Phuc Dang Huu Phung Ton That Tam Nguyen Kieu Thuc Minh Bui