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All Journal Bulletin of Electrical Engineering and Informatics Indonesian Journal of Electrical Engineering and Computer Science
Ha Thanh Tung
Vinh Long University of Technology Education
Electrical & Electronics Engineering

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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.
The impacts of green LaBSiO5: Tb3+, Ce3+ phosphor on lumen output of white LEDs Ha Thanh Tung; Huu Phuc Dang; Phung Ton That
Bulletin of Electrical Engineering and Informatics Vol 12, No 3: June 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v12i3.4772

Abstract

The traditional solid-state technique was used to create LaBSiO5 phosphors doped with Ce3+ and Tb3+ at 1,100 °C. These phosphors' phase purity and luminous characteristics are looked at. Under ultraviolet (UV) light stimulation, LaBSiO5: Tb3+ phosphors emit bright green light, whereas LaBSiO5 samples incorporated with Ce3+ emit blue-violet light. With UV ray stimulation, LaBSiO5 samples incorporated with Ce3+ as well as Tb3+ emit blue-violet as well as green illumination. The 5d-4f shift for Ce3+ is responsible for the blue-violet radiation, while the 5D4→7F5 transition of Tb3+ is responsible for the green radiation. The mechanism for power conversion between Ce3+ and Tb3+ was examined since there is a spectral overlap among the stimulation line for Tb3+ and the emitting line for Ce3+.
The impacts from SrS:Cu+,Na and LaOF:Eu3+ phosphors on color and luminous performances at 5600 K–8000 K WLEDs Ha Thanh Tung; Huu Phuc Dang
Indonesian Journal of Electrical Engineering and Computer Science Vol 30, No 2: May 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v30.i2.pp714-720

Abstract

In terms of lumen performance, the remote phosphor structure can yield better results than the conformal phosphor and in-cup phosphor packages. The application of such a package in LEDs might make the manipulation of the device’s chromatic performance challenging. Two remote phosphor packages are available for raising chromatic performance: one-layer and triple-layer phosphor adjustments. Using software simulation and phosphors created through specific procedures, our study was carried out to select the best adjustment that provides the best results in white LEDs (WLEDs) implemented with many chips: color rendering index (CRI), color quality scale (CQS), lumen output (LO), along with chromatic uniformity. We utilized the WLEDs at five temperatures of color between 5,600 K and 8,500 K. From the outcome, we can consider the three-layer phosphor package to have greater CRI, CQS, and lumen efficiency (LE). Notably, CQS and LE receive a roughly 30% boost compared to singular-layer package. The package can also reduce the chromatic deviation by roughly 30% to 50%, and therefore, grants a boost in chromatic homogeneity. To authenticate these outcomes, the dispersion attribute underwent examination in the layers of phosphor based on Mie-dispersion hypothesis. The outcome may prove useful for creating WLED devices with greater standards.
SrAlOCl:Bi3+@SiO2 phosphor with broad emission band and its effects on LED optical power and correlated color temperature Ha Thanh Tung; Huu Phuc Dang; Hoang Thinh Nhan
Bulletin of Electrical Engineering and Informatics Vol 12, No 4: August 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v12i4.4948

Abstract

Sr3Al2O5Cl2:Bi3+ (SAlOCl:Bi3+)phosphor for broadband emission was made using a solid-state method. From the extensive spectroscopic analysis and theoretical computation, significant conclusions about the origin of the Bi3+ emission were drawn. For the Sr 3 and Sr 1 sites, respectively, the dipole-quadrupole and quadrupole-quadrupole interactions were responsible for the concentration quenching in SAlOCl:Bi3+. The resulting luminescence mechanism demonstrated that the crystallization of Bi3+ at the two sites is what causes the emission from each site. The warm white light emitting diodes (LED) models were built with a 380-nm ultraviolet (UV) chip, SAlOCl:Bi3+, and two other phosphors. Then, the color rendering indeces (CRI) and the correlated color temperature (CCT) were calculated. Particularly, the CRI values ranged from 84.3 to 86.2 under operating currents of 20–50 mA, respectively. The increasing SAlOCl:Bi3+ dosage also heightened particle density, resulting in higher scattering coefficients. High scattering results in improved color coordination (lower color variance). The CRI and luminous flux are reduced as the phosphor SAlOCl:Bi3+ concentration increases more than owing to color loss and energy loss by backscattering and re-absorption. Thus, it is advisable to consider SAlOCl:Bi3+ carefully before applying in production.
The one-phase SrMg2La2W2O12:Tb3+, Sm3+, Tm3+ phosphor and its optical features in multicolor and white-illumination LEDs Ha Thanh Tung; Huu Phuc Dang; Phung Ton That
Bulletin of Electrical Engineering and Informatics Vol 12, No 4: August 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v12i4.4722

Abstract

Researchers propose the phosphors emit many colors SrMg2La2W2O12:Tb3+, Sm3+, Tm3+ (SMLLW:RE3+) (RE3+=Tb3+, Sm3+, Tm3+) synthesized using the solid-status reacting technique as promising downward-transformation luminous substances for diodes emit white illumination and screens in the current study. The structural and binding data given by X-ray diffraction (XRD) data and fourier transform infrared (FTIR) spectroscopy suggest the corresponding orthorhombic configuration and vibrational powers, respectively. The stimulation and radiation bands of color of SMLLW:RE3+ phosphor show that such phosphors may be successfully stimulated via ultraviolet (UV) illumination and generate green, orange-red, and blue (stands for G, O-R, B) illumination, in turn. For different doses of the triggers Tb3+, Sm3+, and Tm3+ within the SMLW phosphor base, luminescence, decomposition periods, Commission Internationale De L'eclairage (CIE) color coordination, along with correlated hue heats (Tcct) are specified. When a triple-doped SMLW phosphor is activated using a ligand-to-metal charge transition (LMCT), it produces G, O-R, B hues at the same time and can be adjustable to white light, according to the results. An effective power transfer among rare-earth ions was found and investigated using decay curve analysis. According to the findings, SMLW:RE3+ (RE=Tb, Sm, Tm) are suitable options to use for light-emitting diodes (LEDs) and screens creation.
Green SrSi2O2N2:Eu2+ phosphor for LED-phosphor applications: synthesis and characterization Ha Thanh Tung; My Hanh Nguyen Thi
Bulletin of Electrical Engineering and Informatics Vol 12, No 5: October 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v12i5.4721

Abstract

Green phosphors SrSi2O2N2:Eu2+ (SSON:Eu) are combined utilizing a simple solid-state reaction with SrSi2O2N2:Eu2+ like the forerunner. Various phosphor attributes were assessed following creation procedure. Differential thermal analysis (DTA) spectra and luminescence measurements are used to assess crystalline active power, electron-phonon conjunction, and heat quenching behavior. Because of their poor electron-phonon conjunction intensity (Huang-Rhys factor=4.2), SSON:Eu green phosphors have outstanding heating and color consistency. The heat quenching temperature (T50) of SSON:Eu is greater than 200 °C. SSON:Eu green phosphors have a wide stimulation range, strong heat steadiness and can absorb ultraviolet (UV) to blue energy and release green illumination, leading to the appropriate utilization in solid-state illumination and GaAsAl solar cells, according to the findings.
Improving the color deviation of white light emitting diode by employing Sr3Ga2Ge4O14:Cr3+ phosphor Ha Thanh Tung; Huu Phuc Dang; Dieu An Nguyen Thi
Bulletin of Electrical Engineering and Informatics Vol 12, No 5: October 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v12i5.5163

Abstract

The pomising uses of near infrared (NIR) phosphor converted light emitting diodes (pc-LEDs), including non-destructive testing and biological implementations, are endless. It is still difficult to create wideband and NIR phosphors with sufficient heating steadiness for a variety of uses. The study herein introduces the phosphor Sr3Ga2Ge4O14:Cr3+, its creation procedure through expreiments as well as its influneces on LED devices. The Sr3Ga2Ge4O14:Cr3+ (SGGO:Cr3+) super-wideband NIR phosphor was effectively synthesized in this study with 431 nm stimulation, and a spectrum adjustment 750 nm-900 nm was made in a two-step superwideband radiation having its full width under half maximum (FWHM) changing among 257 and 336 nm. The inner quantum performance (IQP) for SGGO:0.15Cr3+ is 36.67%, and it has an FWHM of 257 nm. At 423 K, the emitting strength was still 76% of ambient temperature. The potential of SGGO:Cr3+ for various uses was eventually demonstrated by the employment of SGGO:0.03Cr3+ as well as SGGO:0.15Cr3+ samples accompanied by blue illumination chips under 430 nm for the task of creating NIR pc-LED gadgets then putting in nighttime sight, human palm puncture, flora lighting. It was shown that SGGO:Cr3+ has a wide range of use possibilities.
Spatial uniformity of the spectral radiance by white LED-based K2CaP2O7:Ce3+, Tb3+ phosphor Ha Thanh Tung; My Hanh Nguyen Thi
Bulletin of Electrical Engineering and Informatics Vol 12, No 5: October 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v12i5.5344

Abstract

The K2CaP2O7:Ce3+, Tb3+ (Ce/Tb-KCPO) phosphor with blue-to-green emission is introduced in this study. The synthesis of the phosphor is carried out with the solid-state approach. The phosphor characteristics, including X-ray diffraction, luminescence lifespan, and thermal stability are measured and examined. The data show that Ce/Tb-KCPO phosphor displays a broadband emission from blue to green when excited by ultraviolet source. Besides, the ion Ce3+ strengthen the emission of Tb3+ ion through an efficient energy-transfer mechanism, which is estimated about 82.51%. The main electric interaction responsible for this Ce/Tb energy transfer is the dipole-quadrupole one. The phosphor also benefits the luminous intensity and color uniformity of the light-emitting diodes (LED) white-light output. Therefore, the Ce/Tb-KCPO phosphor can be a potential material for high-power white light-emitting diodes (WLED).
Co-Authors Dieu An Nguyen Thi Hoang Thinh Nhan Huu Phuc Dang My Hanh Nguyen Thi Nguyen Le Thai Phung Ton That