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Your search keyword '"Le, Phan Xuan"' showing total 8 results
Start Over Author "Le, Phan Xuan" Topic wleds
8 results on '"Le, Phan Xuan"'

1. A new Ca15(PO4)2(SiO4)6:Eu2+ phosphor with green emission for use in n-UV based WLEDs

Author

Huu, Phuc Dang, That, Phung Ton, and Le, Phan Xuan

Subjects
Color rendering index, Ca15(PO4)2(SiO4)6, Lumen efficacy, Mie-scattering theory, WLEDs
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 solid 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 491 nm, it attains 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 a lightemitting diodes (LED) with converted phosphor (pc-LED) and integrating a 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 pcLED to be able to precede white light-emitting diodes (WLED) implementations.

Published
2022

2. High stability in color chromaticity of warm white emitting diode with dual-hue SrSi2O2N2:Eu2+,Yb2+ phosphor

Author

Thi, My Hanh Nguyen, Le, Phan Xuan, and Thai, Nguyen Le

Subjects
SrSi2O2N2:Eu2+,Yb2+, Color rendering index, Lumen efficacy, Mie-scattering theory, WLEDs
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 for twodoped SrSi2O2N2:Eu2+,Yb2+ (SrYb) nitridosilicate emit a wide emission in the region between green and orange. By 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 codoping 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 containing the acquired phosphor and the indium gallium nitride (InGaN) blue LED chip with 450-nm wavelength was used. With only two steps, we could detect the hue balance management. Firstly, by modifying the Eu2+ and Yb2+ concentrations, we can conduct a green-toorange proportion optimization. Following that, the commission on illumination (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.

Published
2022

3. The luminescence efficiency of green phosphorCa7(PO4)2(SiO4)2:Eu2+ for white light-emitting diode

Author

Bui, Van Liem and Le, Phan Xuan

Subjects
Color homogeneity, Luminous flux, Ca7(PO4)2(SiO4)2, Monte Carlo theory, WLEDs
Abstract

This study examines the green-emission phosphor composition of Eu2+ doped Ca7(PO4)2(SiO4)2 to serve the goal of efficiency enhancement for thewhite light emitting diode (LED). The process of preparation andphotoluminescent investigation of proposed phosphor composition was monitored under near UV excitation wavelength of the LED die. The samplephase was determined using X-ray diffractometer (XRD). To explore Ca7(PO4)2(SiO4)2:Eu2+ capabilities, the diffuse reflectance and photolumine- scence spectral figures were employed. The ultraviolet absorption of Ca7(PO4)2(SiO4)2:Eu2+ ranged from 240 to 440 nm, with a wide bandof green emission peaking at 522 nm. Besides the concentration quenchingmechanism, we also focus on essential characteristics for white-light- emitting diode (WLED) production like temperature-dependent lumenoutput and chromaticity coordinates.

Published
2022

4. High-efficiency green and red phosphors enable a broaderhue-gamut light-emitting diode backlight for brighter displays

Author

Thi, Dieu An Nguyen and Le, Phan Xuan

Subjects
Color homogeneity, Luminous flux, β-sialon:Eu2+, Monte Carlo theory, WLEDs
Abstract

In this article, we suggest combining a blue InGaN chip with strait-bandgreen (β-sialon:Eu2+ ) and red (K2SiF6:Mn4+ ) phosphors to create white light- emitting diodes (WLED) devices with a wide hue range and higheffectiveness that may be utilized in LCD backlighting. The highest radiation wavelength of a gas-pressure sinted β-sialon:Eu2+ is 535 nm, thefull width at half maximum (FWHM) is 54 nm, and the outside quantumperformance is 54.0% lower than the 450 nm stimulation. We createdK2SiF6:Mn 4+ in two steps. The phosphor possesses a sharp line radiationspectrum accompanied by the most intense maximum point under 631 nm, an FWHM reaching roughly 3 nm, as well as an exterior quantumeffectiveness of 54.5%. When computed at 120 mA, the manufactured threerange wLEDs had an illuminating performance of 91–96 lm/Wand a largecolor temperature of 11,184–13,769 K (i.e., 7,828–8,611 K in LCDscreens). The hue range represented by the CIE 1931 and CIE 1976 hue gaps is 85.5- 85.9% and 94.3-96.2% of the NTSC requirement, respectively. Theoptic characteristics outperform those of phosphor-transformed wLEDbacklights utilizing broad-range green or red phosphors, indicating the twostrait-range phosphors studied are the best luminous substances for producing brighter and livelier screens.

Published
2022

6. Comparison between SEPs of CaCO3 and TiO2 in phosphor layer for better color uniformity and stable luminous flux of WLEDs with 7,000 K.

Author

Le, Phan Xuan, Trang, Tran Thanh, Anh, Nguyen Doan Quoc, Lee, Hsiao-Yi, and Tho, Le Van

Subjects
*UNIFORMITY, *SCATTERING amplitude (Physics), *SCATTERING (Physics), *LUMINOUS flux, *PHOSPHORS, *LIGHT emitting diodes
Abstract

CaCO3 and TiO2 are proposed in this study as particles for scattering enhancement (SEPs) of phosphor-converted white light-emitting diodes (pc-WLEDs). The use of these two SEPs for scattering improvement enables boosting of the color homogeneity of the WLED devices. Each SEP is mixed with YAG:Ce3+ and silicone composition to examine their optical influences and performances on the high-power WLED packages with 7,000 K color temperature (CT). Miescattering theory is applied to calculate and investigate the scattering elements – scattering coefficients, anisotropic scattering, the reduced scattering, and scattering amplitudes – at the wavelengths of 450 nm and 550 nm. The results exhibit that TiO2 and CaCO3 considerably promote higher color uniformity and color-deviated reduction, respectively. The obtained results could be primarily attributed to the significant improvement in the scattering properties of the structure. Additionally, the effects of the presented scattering enhancement on luminous efficiency are displayed. The reduction in lumen output is observed to have a close connection with the concentration and particle size of TiO2 and CaCO3, which means that control must be exercised over these factors when utilizing these SEPs for WLED fabrication. [ABSTRACT FROM AUTHOR]

Published
2022
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7. Triple-layer remote phosphor structure: A potential packaging configuration to enhance both color quality and lumen efficiency of 6,000–8,500 K WLEDs.

Author

Le, Phan Xuan, Ho, Sang Dang, Quoc Anh, Nguyen Doan, and Lee, Hsiao-Yi

Subjects
*PHOSPHORS, *LIGHT emitting diodes, *LIGHT scattering, *COLOR temperature, *MOLECULAR spectra, *PACKAGING
Abstract

To achieve further enhancement in the lighting quality of white light-emitting diodes (WLEDs), this study proposed a packaging structure with three different phosphor layers, called triple-layer remote phosphor structure. This structure can provide an overall control over the light color distribution of WLEDs. The yellow-green-emitting CaAl2O4:Mn2+ phosphor and red-emitting CaMoO4:Eu3+ phosphor are used along with the original yellow-emitting YAG:Ce3+ phosphor to fabricate the triple-layer structure. The concentration of yellow-emitting YAG:Ce3+ phosphor is required to be decreased as the concentrations of other phosphors increase to keep the predetermined correlated color temperatures. The color rendering index (CRI) and the color quality scale (CQS) are measured to reach a thorough color quality assessment for WLEDs. The color management can be achieved by adjusting the concentration of red-emitting CaMoO4:Eu3+ phosphor to enhance the red emission. In addition, adjustment of the concentration of yellow-green-emitting CaAl2O4:Mn2+ phosphor can result in higher luminous efficiency owing to its control over the green light components. Higher CRI is observed when CaMoO4:Eu3+ concentration increases, while an increase in CaAl2O4:Mn2+ phosphor leads to much lower CRI. The CQS – on the other hand – is remarkably high when the CaMoO4:Eu3+ concentration range is about 10wt%–14wt%, regardless of the proportion of the CaAl2O4:Mn2+ phosphor. Furthermore, 40% enhancement in luminous efficiency is also achieved since light scattering is minimized by the boosted green-light emission spectra. Manufacturers can take these findings as reference to fabricate high-quality WLED lights that fulfill all their requirements. [ABSTRACT FROM AUTHOR]

Published
2021
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8. The impacts of Ba2Li2Si2O7:Sn2+,Mn2+ and CaMgSi2O6:Eu2+,Mn2+ particles on the optical properties of remote phosphor LED.

Author

Chen, Ming-Jui, Loan, Nguyen Thi Phuong, Van Tho, Le, Bui, Thuc Minh, Le, Phan Xuan, Anh, Nguyen Doan Quoc, Liao, Hsing-Yuan, Chang, Jui-Chen, and Lee, Hsiao-Yi

Subjects
OPTICAL properties, PHOSPHORS, RARE earth metals, TIN, COLOR temperature, LUMINESCENCE, LUMINOUS flux
Abstract

As implied in the title, the triple-layer remote phosphor (TRP), constructed with the yellow YAG:Ce3+ layer at the bottom, the red CaMgSi2O6:Eu2+,Mn2+ phosphor layer on the top, and the green Ba2Li2Si2O7:Sn2+,Mn2+ phosphor layer between these two layers, is suggested in this paper to improve the color and luminescence of white LEDs (WLEDs). In order to control the red light for the purpose of increasing the color rendering index (CRI), it is suggested that the red CaMgSi2O6:Eu2+,Mn2+ phosphor should be applied in the TRP structure. Simultaneously, the structure uses the green Ba2Li2Si2O7:Sn2+,Mn2+ phosphor layer to control the green light, which increases the luminous efficacy (LE) of WLEDs. In addition, when the concentration of these two phosphors increases, the yellow YAG:Ce3+ concentration must be reduced to keep the average correlated color temperatures (ACCTs) stable at 6000 K to 8500 K. Besides, appropriate adjusting of CRI, LE, and color quality scale (CQS) is also analyzed by modifying the concentration of the green phosphor and red phosphor. The results show that the CRI can get better values if CaMgSi2O6:Eu2+,Mn2+ concentration is higher. In contrast, the CRI decreases dramatically when the concentration of Ba2Li2Si2O7:Sn2+,Mn2+ increases. Meanwhile, CQS can be significantly increased in the range of 10 % to 14 % CaMgSi2O6:Eu2+,Mn2+, regardless of the concentration of Ba2Li2Si2O7:Sn2+,Mn2+. In particular, along with the improvement of CRI and CQS, LE can also be increased by more than 40 % by reducing the scattered light and adding the green light. Obtained results are a valuable reference for manufacturers for improving WLEDs color and luminescence quality to produce a broader range of WLEDs with better quality fulfilling social needs. [ABSTRACT FROM AUTHOR]

Published
2020
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