Dieu An Nguyen Thi
Industrial University of Ho Chi Minh

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Journal : Indonesian Journal of Electrical Engineering and Computer Science

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.