Huu Phuc Dang
Industrial University of Ho Chi Minh City

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Effects of (Ba,Ca)ScO2F:Bi3+,K+ phosphor particle size on color uniformity white light-emitting diodes 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.pp707-713

Abstract

Phosphors that offer considerable performance as well as heat consistency has been a high priority of recent studies concerning light-emitting diodes (LED) devices. This study employs the perovskite phosphors BCSOF (short for Ba1-xCaxScO2F:0.001Bi3+,0.001K+ with x value from 0 to 0.12 and one chip at 415 nm generating thin green illumination via cation-replacement method. The study examines the aftermath when Ca2+ replaces Ba2+ within the crystal formations of BCSOF as well as the luminescent features of the phosphors, detecting a formation of cube-like perovskite within the space group of Pm3m in the employed phosphors. In addition, the study also assesses the development concerning the magnitude of cells as well as the binding extent of Ba/Ca/K/Bi-O. When the inner quantum performance reaches 77.4% in BCSOF, a potent green discharge is manifested, reaching 510 nm when excited by a chip at 415 nm. Greater luminescent performance as well as heat consistency correlating with changes in inner formation were reported. Via the method of replacing cations, it is possible to control spectrum by manipulating the latticework’s surroundings, leading to desirable performance in LED products.
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.
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.