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The application of phosphor Sr4La(PO4)3O:Ce3+,Tb3+,Mn2+ on white light-emitting diodes My Hanh Nguyen Thi; Phan Xuan Le
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.pp1251-1257

Abstract

Using a high temperature solid-state technique, various phosphors Sr4La(PO4)3O:Ce3+, Tb3+,Mn2+ (SLPO:Ce,Tb,Mn) were produced. In Sr4La(PO4)3O, the luminescence characteristics, thermal stability, and energy conversion between Ce3+ and Tb3+-Mn2+ have been thoroughly studied. The sensitizer Ce3+ particles inclusion could considerably improve the feeble Tb3+ green radiation and Mn2+ red radiation via energy transfer. By adjusting the scale of Ce3+/Tb3+ over Ce3+/Mn2+ atoms, the color of the emission may be changed. White light was produced in the Sr4La(PO4)3O:0.12Ce3+,0.3Mn2+ specimen with chromatism coordinates of (0.3326, 0.3298), showing that the phosphors SLPO:Ce,Tb,Mn possess promising application on WLEDs. The conclusion is supported by Mie-scattering theory and Lambert-Beer's law.
The impacts of green Cs2ZnSi5O12:Eu2+ phosphor for white light emitting diode Van Liem Bui; Phan Xuan Le
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.pp1270-1275

Abstract

We created the green-light phosphor Cs2ZnSi5O12 (CZSO) with Eu2+ replacement for the practical use of ultraviolet white illumination through the solid-state technique. The phosphor displays many different forms and crystallizes in the space group Pbca along with Pa , with formation resembling CsAlSi2O6, the leucite in cube form. We utilized the X-ray powder diffraction as well as the spectroscopic knowledge to validate that the crystal formation in the phosphor CZSO:Eu2+ belongs to the space group Pa . CZSO can generate wide green emission with a wavelength of 504 nm when excited by ultraviolet. We enveloped the blend using the translucent silicone resin and the red-light phosphor Sr2Si5N8:Eu2+ as well as excited it using an ultraviolet light emitting diode (LED) device with a wavelength of 370 nm to generate white illumination that yields remarkable chromatic output. The generation of illumination utilizing the phosphor CZSO benefits from the wide green emission, which does not require the integration of the three phosphors that are critical to the ultraviolet pumping. Such benefit will allow the model of the apparatus to become simpler and simultaneously create a desirable ultraviolet white illumination. When the augmentation the emission efficacy as well as the heat consistency for the phosphor CZSO is realized, we can easily incorporate the ultraviolet LED devices to create better white illumination.
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.
A new Ca15(PO4)2(SiO4)6:Eu2+ phosphor with green emission for use in n-UV based w-LEDs Phuc Dang Huu; Phung Ton That; Phan Xuan Le
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.pp1276-1281

Abstract

We have produced a novel phosphor using Eu2+, which is green in color coupled to Ca15(PO4)2(SiO4)6 (abbreviated as Ca15P2Si6) by deriving it structurally from α-Ca2SiO4 with a typical solit reaction method. Additionally, the decrease of Eu2+ concentration as well as heat endurance is being studied. 330 nm is the wavelength at which the substance is stimulated. At 491nm, it attain the greatest radiation energy  when filled with the ideal concentration of Eu2+, which is 0.5 mol%. The primary mechanism of concentration reduction is discovered to be the fast transfer of stimulation through exchanging coupling among stimulated Eu2+ ions. The heat activating power boundary has been determined to be 0.244 eV. Additionally, we assess the productivity of this matter by fabricating alight-emitting diodes (LED)with converted phosphor (pc-LED) and integrating a light-emitting diode (LED) with an InGaN-foundation near-ultraviolet and running it at currents between 50 mA and 300 mA. All of the efforts result in an optimal for pc-LED to be able to ecedewhite light-emitting diodes (WLED) implementations.
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.
The qualities of dyed YAG:Ce3+@SiO2 for WLEDs via energy conversion Phung Ton That; Phan Xuan Le
Bulletin of Electrical Engineering and Informatics Vol 11, No 5: October 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i5.4064

Abstract

Y3Al5O12:Ce3+ (YAG:Ce3+), the most common yellow phosphor for WLEDs, has a red insufficiency in its light spectrum. The Ce3+ spectral profile is modified in this research using surface-located ATTO-Rho101 dye molecules, which have powerful, wide impregnation in the greenish-yellow spectroscopic zone of Ce3+ radiation and vivid red-emitting radiation. To create a spherical shell and evenly dispersed micro and nanometer YAG:Ce3+, a modified solvothermal technique is applied. Surface SiO2 covering and synchronized dye embedding are accomplished using solvothermally generated YAG:Ce3+, temperature-stimulated micro-YAG:Ce3+, plus commercialized phosphorus. Upon blue light excitation, the accumulated YAG:Ce3+@SiO2+dye powder exhibits efficient radiative conversion/reintake from Ce3+ within the internal structure of YAG to the pigment particles from the SiO2 external shell, despite the phosphors' diameter; which likely boosts its red radiation. Fluorescence microscopy would be a suitable way to determine the reabsorption of powdered substances.
The color-adjustable phosphor Sr4La(PO4)3O:Ce3+,Tb3+,Mn2+ of WLEDs: luminescence and transfer of energy characteristics Phuc Dang Huu; Phan Xuan Le
Bulletin of Electrical Engineering and Informatics Vol 11, No 5: October 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i5.4062

Abstract

A high heat solid-state technique was used to produce a set of phosphor Sr4La(PO4)3O:Ce3+,Tb3+,Mn2+ (Sr:Mn). In Sr4La(PO4)3O, the luminescence characteristics, heat resistance, and energy conversion between Ce3+ and Tb3+ as well as Mn2+ were thoroughly researched. Introducing the activator Ce3+ particles can significantly increase the dim green-emitting from Tb3+ and the red-emitting from Mn via energy conversion. The color of the emissions might be changed by adjusting the Ce3+/Tb3+ and Ce3+/Mn2+ ion ratios. In the Sr4La(PO4)3O: 0.12 Ce3+,0.3 Mnz2+ specimen, we achieved white-emitting illumination, yielding hue coefficients (0.3326, 0.3298), showing that the phosphor Sr:Mn could have promising implications for white light-emitting diodes (WLEDs).
Superior hue output as well as lumen for WLEDs with dual-sheet distant layouts of phosphor Phuc Dang Huu; Phan Xuan Le
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 20, No 6: December 2022
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v20i6.24083

Abstract

Remote phosphor constructions usually have color quality drawbacks but are more luminous in terms of lumen, surpassing conformal phosphor or in-cup layouts of phosphor. From this disadvantage, there is a great number of studies carried out to boost the chromatic performance in remote phosphor (RP) structures. This work focuses on using a two-layer RP or dual-film RP (DFRP) to improve the color rendering indices (CRI) as well as color quality scales (CQS) for white light emitting diodes (WLEDs). Two equivalent dual remote phosphor (DRP) structures for WLEDs operating at various temperatures of color including 5600 K, 7000 K, as well as 8500 K will be employed for our study. The study’s idea involves putting one phosphor Zn2SiO4:Mn2+,P layer or one red phosphor Mg2SiO4:Mn2+ layer on top of the yellow YAG:Ce3+. Subsequently modifying the concentration for each red and green phosphor to investigate the changes in color metrics and luminous flux. As a result, a suitable red and green phosphor concentration can be determined to acquire desired outcomes for each DFRP-WLED. Obtained results show that Mg2SiO4:Mn2+ performs significant boosting on both CRI and CQS, especially when being integrated with increasing concentration, thanks to the increased red-light presence for the WLED device. In addition, the sheet of phosphor Zn2SiO4:Mn2+,P benefits the luminous flux.
Benefits of using TiO2 quantum dots in producing low-cost and high-quality white light-emitting diodes Phuc Dang Huu; Phung Ton That; Tran Thanh Trang; Phan Xuan Le; Nguyen Doan Quoc Anh
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 20, No 3: June 2022
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v20i3.15347

Abstract

Quantum dots (QDs) is considered as a potential material for the improvement of light-emitting diodes (LEDs). However, different from the traditional phosphor materials, they have unique scattering and absorption properties affected by their several nanometers sizes, which makes their application in the production of LED confront more challenges. In addition to this, their influences on QDs-converted LEDs (QCLEDs) are rarely investigated. So as to propose solutions for those problems, in this article, we experimentally and theoretically investigated the impacts of titanium dioxide (TiO2)QDs’ scattering and absorption on the light quality of QCLEDs by drawing a thorough comparison between their properties and the traditional yttrium aluminum garnet phosphors characteristics. The outcomes showed that QCLEDs have poor radiant efficacy and stability due to QDs’ strong characteristic of absorption (reabsorption) while their weak scattering property causes a low uniformity in correlated color temperature (CCT). For achieving high efficiency and stability white LEDs, we highly suggest using QDs with a low concentration to get reductions in the reabsorption and total internal reflection losses. With 0.05 concentration of TiO2 nanoparticles (TiO2 NPs), the white LEDs can simultaneously achieve a high CCT (approximately 7500 K) and a high color rendering index (around 85).
Application of dual-layer phosphor geometries for enhancing the optical properties of white-light LEDs Phung Ton That; Hsiao-Yi Lee; Phan Xuan Le
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 20, No 6: December 2022
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v20i6.24098

Abstract

This article compares the lumen output of two packages of two-remote phosphor (RP). The first package is flat dual-remote phosphor (FDRPS). The second package is concave dual-remote phosphor (CDRP). The dispersion qualities of the white-light-emitting diode are different as a result of their different cover designs, leading to a disparity between the FDRPS and CDRPS configurations. The results of the study show that the FDRPS package yields a lumen output superior to that of the CDRPS package. In the article, we can also see how the space among the phosphor films (?1) and the space among the phosphor film and the light emitting diodes (LED) outer side (?2) might affect the light characteristics in the CDRPS model. As the indicated distances shift, the characteristics of dispersion and absorptivity in the distant phosphor film will shift as well. Such an occurrence can have an impact on chromatic uniformity as well as optical performance in white light emitting diodes (WLEDs). If we modify the  and  values, it is necessary to change the phosphor YAG:Ce3+ concentration in the WLEDs to keep the correlated color temperature at 8500 K.