Huu Phuc Dang
Industrial University of Ho Chi Minh City

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Journal : telkomnika telecommunication computing electronics and control

Utilizing CaCO3, CaF2, SiO2, and TiO2 phosphors as approaches to the improved color uniformity and lumen efficacy of WLEDs Huu Phuc Dang; Phung Ton That; Nguyen Doan Quoc Anh
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 2: April 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i2.16357

Abstract

The two elements that are most favorable in the quality evaluation for phosphor-converted LEDs (pcLEDs) these days are the chromatic homogeneity and the lumen output. In this study, a thorough research on enhancing color uniformity and luminous flux of pcLEDs that have a high correlated color temperature (CCT) of 8500K is carried out. The scattering enhancement particles (SEPs): CaCO3, CaF2, SiO2, and TiO2 are used to accomplish the goal by adding them to a yellow phosphor compounding Y3Al5O12:Ce3+, and comparing their characteristics afterwards. LightTools program is used to build an optical simulation and Mie-scattering theory helps to examine the achieved results. Specifically, the parameters included in SEPs’ scattering calculation are the scattering coefficients, the anisotropic scattering, the reduced scattering, and the scattering amplitudes at 455 nm and 595 nm. The outcomes presented that compared to other SEPs, TiO2 particles can yield the highest chromatic homogeneity. However, the lumen output reduces considerably as TiO2 concentration greatly increases while it can be bettered when using SiO2 particles with any particle size. For CaCO3 particles, the color deviation of 620 K CCT can be reduced with 30% concentration, leading to the recommendation of using CaCO3 to promote the CCT homogeneity and luminescence efficiency.
Effects of BaSO4 nano-particles on the enhancement of the optical performance of white LEDs Huu Phuc Dang; Phung Ton That; Dao Huy Tuan
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 2: April 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i2.16855

Abstract

The usage of BaSO4 nanoparticles on WLEDs luminous flux and color uniformity improvements have been analyzed and demonstrated in this manuscript. The mixture of BaSO4 and silicone placed on the yellow phosphor layer benefits the internal light scattering and thus enhances the angular correlated color temperature (CCT) homogeneity. Specifically, the blue-light intensity at large angles tend to increase and results in light intensity discrepancy, which can be corrected with added BaSO4. In addition to this, the BaSO4-silicone composite modifies the refractive index of the air-phosphor layer interface to an appropriate value, and thus, the luminous efficiency increases. The results show that the CCT deviations is reduced by 580 K, from 1000 K to 420 K, within the angle range from -700 to +700 with BaSO4 in the phosphor structure. The increase in luminous flux is also recorded by 2.25%, in comparison with that of the non-BaSO4 traditional structure, at the 120-mA driving current. Hence, integrating BaSO4 nanoparticles into the remote phosphor structure can contributes to the enhancement of both lumen output and CCT uniformity.
Multilayer phosphor-in-glass packaging for the development in WLED color uniformity Huu Phuc Dang; Phung Ton That; Tri-Vien Vu
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 3: June 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i3.17786

Abstract

When mentioning the remote phosphor structure, the most noticeable advantage is its higher luminous flux than any other structure’s. However, there are existing flaws in their color uniformity and color rendering index (CRI). Thus, the improvements in these two optic factors must be improved for the better usage of remote phosphor geometry in modern WLED devices. Many researchers have drawn their attention to this idea, and then it has become the primary objective for their studies. In this paper, we also try to accomplish the same result by adjusting the distances between the phosphor layers and through that enhance the optical properties of WLEDs. The mie-scattering theory is applied in our calculations to ensure the reliability and accuracy of experimental results. In our research, with distance d = 0.64 mm, the luminous flux grew 9.7% in comparison to the original value. At 0.84 mm, the distance d enhanced the color uniformity by two times. In the meantime, the CRI remained static during the course of experiment. With suitable application, these results can bring valuable contributions to the development of next WELDs generation.
Research on advancing chromatic reproduction and luminosity of a WLED using triple-layer remote phosphor arrangement Ha Thanh Tung; Huu Phuc Dang
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 21, No 2: April 2023
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v21i2.24744

Abstract

In this study, the use of triple-sheet phosphor arrangement (TRP) in performing significant improvements to both color quality and luminous flux of white light emitting diode (WLEDs) is introduced. The phosphor layer of CaLaB3O7:Ce3+,Mn2+ is to accomplish green-spectra enhancement for the boost of luminous efficacy (LE), while MgB2O4:Mn2+ red phosphor layer is for red-spectra enhancement to better color rendering index (CRI) of WLEDs. The changes in these two phosphors’ concentrations present considerable effects on the yellow phosphor YAG:Ce3+ concentration, the color quality scale (CQS), CRI, and LE. Findings display the decrease of YAG:Ce3+ concentration accompanying the increase of red and green phosphor concentrations, for the stabilized average correlated color temperatures (ACCTs) between 6000 and 8500 K. Results also reveal that greater content of MgB2O4:Mn2+ leads to greater CRI value. Meanwhile using the increasing CaLaB3O7:Ce3+,Mn2+ concentration, the CRI lowers considerably. CQS, on the other hand, can increase with CaLaB3O7:Ce3+,Mn2+ concentration from 10% to 14%. Especially, given the enhancement for the CRI as well as CQS, LE value will surge to more than 40% due to the reduction of scattering light and the addition of green light. The outcome of the study is a priceless reference for light emitting diode (LED) producers.
Study of Ba2Li2Si2O7:Eu2+ phosphor for enhancing the luminous flux of white LEDs Ha Thanh Tung; Huu Phuc Dang
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 21, No 3: June 2023
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v21i3.24748

Abstract

The best spectrum characteristics and photometric productivities of white light emitting diode (WLED) device possessing light emitting diodes (LEDs) in red rather than phosphor pc/R-WLEDs with the hue fidelity index (Rf) > 97 for correlated color temperatures (CCTs) between 2700 K and 6500 K were attained using the illumination effectiveness (LE) model. We demonstrate four practical pc/R-WLEDs that have indices of Rf and LE of 96–97 and 120–124 lm/W, respectively, under CCT values measured at 2969 K, 4468 K, 5682 K, as well as 6558 K. These LED packages use blue and red LEDs, also phosphors in green as well as yellow, with respective wavelengths of 448 nm, 650 nm, 507 nm, and 586 nm. In the comparison between phosphor-transformed WLED devices (with phosphor conversion) and quantum-dot WLED devices (QD-WLEDs), pc/R-WLEDs make an outstanding performance in competitiveness for high hue generation, particularly under small CCT values, and could eventually replace current pc-WLEDs.
Using phosphor ZnB2O4:Mn2+ for enhancing the illuminating beam and hue standard in white light-emitting diodes Ha Thanh Tung; Huu Phuc Dang
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 21, No 3: June 2023
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v21i3.24749

Abstract

The enhancement in hue uniformity and luminous production of multiple-chip white LED lamps (MCW-LEDs) using dual-layer remote phosphor packaging designs are the emphases of this paper. We blended Mn2+ activated strontium–barium silicate (ZnB2O4:Mn2+) with the phosphor mixture and manage to record significant impacts of this new phosphor mixture on the LED lights’ lighting performance. There is evidence that the growing concentration of yellow-green-emitting ZnB2O4:Mn2+ phosphor encourages the enhancement of hue uniformity and illumination effectiveness in MCW-LEDs with mean correlated hue heats (CCTs) of roughly 8500 K, though the color quality scale is gradually deteriorating. It is possible to successfully achieve such amazing MCW-LED performance if we choose the right concentration and size of ZnB2O4:Mn2+.