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All Journal Indonesian Journal of Electrical Engineering and Informatics (IJEEI) Indonesian Journal of Electrical Engineering and Computer Science
Dieu An Nguyen Thi
Industrial University of Ho Chi Minh
Computer Science & IT Electrical & Electronics Engineering

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Study of LaSiO3Cl:Ce3+,Tb3+ and Ca5B2SiO10:Eu3+ Phosphors for Improving Hue Standard and Illuminating Beam of WLEDs Dieu An Nguyen Thi; Phan Xuan Le
Indonesian Journal of Electrical Engineering and Informatics (IJEEI) Vol 10, No 2: June 2022
Publisher : IAES Indonesian Section

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.52549/ijeei.v10i2.3237

Abstract

Remote phosphor arrangements usually have low color quality and superior lumen output to that of conformal phosphor arrangements and in-cup phosphor arrangements. For this reason, many researches are done so that we could enhance the chromatic quality for the remote phosphor arrangements. For this research, we are suggesting the double-layer remote phosphor arrangement to boost the CRI (short for color rendering index) as well as the CQS (short for color quality scale) in WLED devices. Three identical WLED arrangements which have dissimilar chromatic temperature which covers 5600 K, 8500 K will be used in this paper. The initial idea involves placing one sheet of blue phosphor LaSiO3Cl:Ce3+,Tb3+ or one sheet of red phosphor Ca5B2SiO10:Eu3+ over a sheet of yellow phosphor YAG:Ce3+. After that, seek an appropriate concentration of Ca5B2SiO10:Eu3+ so that we could obtain the most desirable chromatic performance. Judging the result, the element Ca5B2SiO10:Eu3+ seem to help improve the CRI and CQS levels. Particularly, the greater the concentration of La2O3:Eu3+ is, the greater level the CRI and the CQS will get, because of the boost in red illumination within the WLED devices. In addition, the blue phosphor layer LaSiO3Cl:Ce3+,Tb3+ helps increase the lumen output. But the decline of the lumen as well as the chromatic performance manifests if the concentration of LaSiO3Cl:Ce3+,Tb3+ and Ca5B2SiO10:Eu3+ is beyond required level. This is demonstrated by utilizing the theory of Mie-scattering as well as the law of Beer–Lambert. This research’s result is important for the augmentation of white light performance in the WLED devices.
Selection of Gd2(WO4)3:Tb3+ for inproving color deviation in white light-emitting diodes Dieu An Nguyen Thi; Nguyen Doan Quoc Anh; Phan Xuan Le
Indonesian Journal of Electrical Engineering and Computer Science Vol 27, No 2: August 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v27.i2.pp709-714

Abstract

This study successfully using the hydrothermal technique to synthesize Gd2(WO4)3:Tb3+ phosphors when subjected to calcination under the temperature of 900°C. Here are some aspects that were thoroughly examined: the crystal formation, photoluminescence, photoluminescence excitation, as well as fluorescent degradation for the samples. The (Gd2-xTbx)(WO4)3 (x=0.01-0.15) phosphors exhibit a bright discharge of green under 547 nm (5D4→7F5 shift for Tb3+) when excited at 270 nm (4f8→4f75d1 shift for Tb3+). Because of the exchange interaction between Tb3+, the quenching concentration was determined to be around 10%. The addition of Tb3+ had no effect on the (Gd2-xTbx)(WO4)3 phosphors' CIE chromaticity coordinates (~0.33±0.02, ~0.60±0.02) or color temperatures (~5542 K). Nevertheless, when the Tb3+ content increased, the fluorescence lifespan for 547 nm emission reduced due to energy transfer between Tb3+. The strong green emission from Gd2(WO4)3:Tb3+ phosphors is a potential element for WLEDs and display areas.
Application of (Ca1-xSrx)LaGa3S6O:Eu2+ phosphor in white light-emitting fabrication Dieu An Nguyen Thi; Phan Xuan Le
Indonesian Journal of Electrical Engineering and Computer Science Vol 27, No 2: August 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v27.i2.pp735-740

Abstract

An alternating sequence of Ca1-xSrxLaGa3S6O:0.05Eu2+ phosphors was produced using high-thermal and solid-state reactions. It has outstanding excitations at the range between 350 and 500 nm suitable for the close-ultraviolet or GaN-based blue LED chips. These phosphor peaks have a blue shift between 560 and 540 nm when the Sr concentration (x) rises. The Sr content (x) can be modified to produce an illumination with a color between yellow and green. As a result, we can conclude that solid solutions Ca1-xSrxLaGa3S6O:0.05Eu2+ are excellent for use in manufacturing white LEDs. Our data may become valuable for producers in the task of making white light emitting diode (WLED) devices suitable for them.
High-efficiency green and red phosphors enable a broader hue-gamut light-emitting diode backlight for brighter displays Dieu An Nguyen Thi; Phan Xuan Le
Indonesian Journal of Electrical Engineering and Computer Science Vol 27, No 2: August 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v27.i2.pp741-747

Abstract

In this article, we suggest combining a blue InGaN chip with strait-band green (β-sialon:Eu2+), red (K2SiF6:Mn4+) phosphors to create WLED devices with a wide hue range and high effectiveness that may be utilized in LCD backlighting. The highest radiation wavelength of a gas-pressure sintedβ-sialon:Eu2+ is 535 nm, the full width at half maximum (FWHM) is 54 nm, and the outside quantum performance is 54.0% lower than the 450 nm stimulation. We created K2SiF6:Mn4+ in two steps. The phosphor possesses a sharp line radiation spectrum accompanied by the most intense maximum point under 631 nm, an FWHM reaching roughly 3 nm, as well as an exterior quantum effectiveness of 54.5%. When computed at 120 mA, the manufactured three-range wLEDs had an illuminating performance of 91–96 lm/W and a large color temperature of 11,184–13,769 K (i.e., 7,828–8,611 K in LCD screens). 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.  The optic characteristics outperform those of phosphor-transformed wLED backlights utilizing broad-range green or red phosphors, indicating the two strait-range phosphors studied are the best luminous substances for producing brighter and livelier screens.
Co-Authors Nguyen Doan Quoc Anh Phan Xuan Le Phan Xuan Le