Phuc Dang Huu
Thu Dau Mot University

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Journal : Bulletin of Electrical Engineering and Informatics

Two-layer remote phosphor package as a solution to promote color quality scale and lumen in WLEDs Phuc Dang Huu; Dieu An Nguyen Thi
Bulletin of Electrical Engineering and Informatics Vol 11, No 3: June 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i3.3766

Abstract

This article demonstrates the influence of the red-light LaAsO4:Eu3+ phosphorus on the optical features of the two structures: one-layer remote phosphorus scheme (SRPS) and two-layer remote phosphorus scheme (DRPS). As a result, the Mie hypothesis is used to demonstrate and prove the comparison between color quality and luminosity (LF) between these two factors. The SRPS is a phosphor layer that consists of LaAsO4:Eu3+ particles combined with the YAG:Ce3+ mixture. Meanwhile, DRPS is two phosphor layers of red and yellow separated from each other. To improve the dispersing property, 5% of SiO2 is combined with the phosphorous films. The difference between the structures influences the optical features of WLEDs. The obtained outcomes show that the color rendering index (CRI) rises along with the concentrations of both structures while these values are nearly identical to each other. Meanwhile, at ACCTs (5600 K - 8500 K), the color quality scale (CQS) in DRPS reaches 74, which is higher than SRPS's 71 at 8500 K. Besides, the lumen in DRPS is considerably greater than that in SRPS at 2%-14% LaAsO4:Eu3+. In short, DRPS brings considerable benefits to the color quality and lumen when compared to SRPS. In addition, choosing a suitable concentration also becomes highly vital to achieve desirable CQS and LF.
Using liquid phase precursor method to create a high-efficiency Ca2SiO4:Eu2+ green-emitting phosphor Phuc Dang Huu; Dieu An Nguyen Thi
Bulletin of Electrical Engineering and Informatics Vol 11, No 3: June 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i3.3767

Abstract

A standard solid-state reaction (SSR), a new fluid phase preparatory method utilizing LPP-SiO2(sol), and a water-based soluble silicone compound were employed to manufacture green Eu2+-based Ca2SiO4 phosphors liquid phase precursor (LPP-WSS). The generated phosphors feature large excitation spectra in the range of 225–450 nm and a strong green emission reaches the peak value at 502 nm owing to a 4f65d1→4f7(8S7/2) transition of Eu2+. These samples burned at 1100 1C produce the highest luminous intensity. The luminous properties of phosphors, which are manufactured by the liquid phase precursor LPP-WSS technique, were investigated at the range of 0.1-5.0 mol percent of Eu2+, with the maximum emission density observed at the value of 3.0 mol percent of Eu2+. The phosphors produced by the LPP-WSS technique exhibited a more uniform phase dispersion and higher luminous strength than those produced using the other procedures, according to a detailed report based on numerous characterizations. As a result, Ca2SiO4:Eu2+ has an indisputable possibility in white light-emitting diodes WLEDs and fluorescent lighting.
Application of green-emitting Sr3WO6:U phosphor to enhance lumen efficiency of WLEDs Phuc Dang Huu; Ton That Phung
Bulletin of Electrical Engineering and Informatics Vol 11, No 2: April 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i2.3301

Abstract

The article demonstrates a sample of spectrum in the phosphor-covered WLED (abbreviated as p-WLED) containing one blue chip, one red chip along with phosphors of green and yellow colors. We acquired the p-WLEDs’ ideal spectrum in the CCTs, which is short for correlated color temperature range from 2700 K to 6500 K using a nonlinear program in order to optimize the radiation’s lumen efficiency (LER) when the R9 strong red's color rendering indexes (CRIs) and special CRIs exceed 98. From the outcomes of the recreation, p-WLEDs containing an InGaN blue chip with 450 nm wavelength, an AlGaInP red chip with 634 nm wavelength, along with green and yellow silicate phosphors with the value of 507 and 580 nm wavelength correspondingly; can produce white lights with CRI values of around 98 and particular CRI values of R9 for intense reds above 98. For saturated red, yellow, green, and blue colors, the average values of the particular CRIs R9 through R12 exceed 95. In CCT values of 2700 K to 6500 K, the R13 value in female figures is around 100, with LER values reaching 296 lm/W.
CaS: Sb3+, Na and ZnS:Sn2+: phosphor materials for the improvement of WLEDs Phuc Dang Huu; Ton That Phung
Bulletin of Electrical Engineering and Informatics Vol 11, No 2: April 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i2.3300

Abstract

The remote phosphor configuration, though not the best choice for WLED color quality, is superior to the luminous flux of LEDs compared to the conformal or in-cup structures. Realizing the capability of the remote phosphor design, several studies have been done to overcome the drawback of this structure, which is the color quality. A two-film distant phosphor configuration with improved color rendering index (CRI) and color quality ratio (CQS) for WLEDs is offered in this study paper. The hue temperature of the WLEDs packets employed in this research is 8500 K. This phosphor structure is constructed by layering of a green CaS:Sb3+,Na or red ZnS:Sn2+ phosphor above the yellow YAG:Ce3+ phosphor. The additional phosphor ZnS:Sn2+ concentration will then be modified to get the best color quality. The results demonstrated an increase in CRI and CQS along with the presence of ZnS:Sn2+, indicating that the existence of ZnS:Sn2+ influences significantly on these two aspects. As a result of the increased concentration of red illumination elements inside packets, the higher the concentration of ZnS:Sn2+, the higher the CRI and CQS. The green phosphor CaS:Sb3+,Na, in the meantime, improves the luminous flux.
Enhancing optical properties of WLEDs with LaOF:Eu3+&SiO2 application Phuc Dang Huu; My Hanh Nguyen Thi
Bulletin of Electrical Engineering and Informatics Vol 11, No 1: February 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v11i1.2910

Abstract

After many efforts, the core-shell nanostructure of LaOF:Eu3+SiO2 that emits bright red radiation can be fabricated by simple solvothermal application succeeded by heat treatment. The resulted particles from the fabrication process are small in size, able to demonstrate circular form more efficient and prevent stacking. Photoluminescence (PL) emission spectra exhibits intense peaks at 593 nm, 611 nm, 650 nm corresponds to 5D0 -- 7FJ (J = 0, 1 and 2) Eu3+ transitions respectively. The spectral intensity parameters and Eu-O ligand behaviors are estimated by means of Judd-Ofelt (J-O) theory. CIE co-ordinates are found to be (x = 0.63, y = 0.36) which is very close to standard NTSC values (x = 0.67, y = 0.33). CCT value is 3475 K which is less than 5000 K, as a result this phosphor is suitable for warm light emitting diodes. The optimized core-shell SiO2 (coat III)@LaOF:Eu3+ (5 mol%) was used as a fluorescent labeling marker to identity latent fingerprints on both porous and non-porous surfaces. The fingerprints results are highly sensitive, selective and also has no obstruction caused by the back-ground which supports level-I to level-III fingerprint ridge recognition. The experiments outcomes suggest that the enhancements brought by the core-shell NS structure can be further examined to apply in forensic and solid state lightning applications.