Phung Ton That
Industrial University of Ho Chi Minh City

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Journal : TELKOMNIKA (Telecommunication Computing Electronics and Control)

Green Ca2La2BO6.5:Pb2+ phosphor: an innovative solution in enhancing the color quality and luminous flux of WLEDs Phung Ton That; Nguyễn Đoàn Quốc Anh
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 5: October 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i5.14672

Abstract

Light-emitting diodes devices that embedded with multiple chips (multi-chip white LEDs (MCW-LEDs)) are an advanced lighitng solution with much potential for improvement in the lighting industry. However, to further the applicacations and quality of white light emitting diodes (WLEDs) greater achivements must be found, thus, this paper focus on improving the color uniformity and luminous flux with green phosphor Ca2La2BO6.5:Pb2+. The results, which were measured through experiments conducted in WLEDs with average correlated color temperature from 6600–7700 K, show enhancements in color uniformity and luminous efficacy. In particular, the growing trend in the concentration of green phosphor Ca2La2BO6.5:Pb2+ results better color uniformity and lumnous flux, although the color quality scale (CQS) suffers a small decline. Therefore, it is confirmed that the Ca2La2BO6.5:Pb2+ phosphor is suitable in manufacturing WLEDs that focus on the color uniformity and luminous flux.
Integrating SiO2 nanoparticles to achieve color uniformity and luminous efficiency enhancement for white light emitting diodes Phan Xuan Le; Phung Ton That
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 5: October 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i5.20484

Abstract

A phosphor structure with SiO2 nanoparticles is proposed to achieve the enhancement in the correlated color temperature (CCT) homogeneity and the luminescence performance for white light-emitting diodes (WLEDs). As SiO2 is integrated into the phosphorus compound, the scattering effect of this material contributes to better blue-light utilization. Thus, this innovative packaging design results in a significant increased lumen efficiency, more than 12%, in comparison with that of conventional dispensing ones. Meanwhile, the angular CCT deviation also decreases considerably, from 522 K to 7 K, between the angles of -70 and 700. Moreover, this reduction leads to the diminishment of yellow ring phenomenon effect. In addition, the measurement of haze demonstrates that there is a strong scattering in the visible spectrum when SiO2 is added into the silicone film. Besides that, when increasing the driving current, SiO2 stabilizes the chromaticity coordinate shift, which is a vital requirement for indoor lighting applications. Furthermore, SiO2 nanoparticles own excellent optical features, cost efficiency, and simple production will probably turn this material into a potential material in advancing the optical performance of WLEDs.
The analysis of MF resin and CaCO3 diffuser-loaded encapsulations to enhance the homogeneity of correlated color temperature for phosphor-converted LEDs My Hanh Nguyen Thi; Phung Ton That
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.v19i2.16519

Abstract

The most popular method used in the production of phosphor-converted LEDs (pc-LEDs) is dispensing phosphor freely. However, this method is inferior in generating good angular correlated color temperature (CCT) homogeneity. Thus, in this article, a diffuser-loaded encapsulation is proposed as a potential solution for better CCT uniformity. The paper provides a detailed investigation on how melamine formaldehyde (MF) resin and CaCO3 loaded encapsulations impact the uniformity of CCT, as well as the lumen efficacy of pc-LEDs. The results demonstrate that between MF resin and CaCO3 loaded encapsulations, the MF resin yields a higher light diffusion efficiency while the CaCO3 maintains greater lumen efficacy. The photon scattering development is the key force behind the enhancement of the angular CCT uniformity in pc-LEDs’ output when using the loaded encapsulations of MF resin and CaCO3 particles. Since this package utilized mineral, it has reasonable cost and is quite easy to control while still being effective in enhancing the angular CCT homogeneity of pc-LEDs. Diffusers with 1% concentration of MF resin or 10% concentration of CaCO3 are determined as an optimal solution for reducing the variance of angular CCT and increasing the lumen output.
The impacts of red-emitting phosphor Mg8Ge2O11F2:Mn4+ on the color rendering index of convex-dual-layer remote phosphor WLEDs at 5600 K My Hanh Nguyen Thi; Phung Ton That; Nguyen Doan Quoc Anh
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.v19i3.15832

Abstract

The poor color rendering index (CRI) induced by mono chip and phosphor configuration in the conventional white-light light-emitting diode (LED) urges for developments in both packaging and material, thus, a modern lighting solution was introduced. The dual-layer phosphor package is an innovative configuration that can retain the lumen output of conventional white light emitting diode (WLED) while also enhancing color quality. The structure of dual-layer phosphor package that was proposed includes two chips and one phosphor. The priority in this research is to keep improving the lighting properties of WLED, therefore, further experiments with this dual-chips and dual-phosphor package are conducted. The lighting properties of LED are measured multiple times with its nitride-based phosphor being altered in proportions and densities each occasion, the results are calculated with a color design model made specifically to monitor and adjust the color of white-light from LED to match desired outcome. The WLED at 5600 K correlated color temperature (CCT) is the sole research object of the experiments. The measured parameters from the 5600 K WLED and the color coordinates of CIE 1931 simulated from the color design model show that 0.0063 is the highest possible discrepancy at 5600 K (CCT). The information from this manuscript provide the manufacturers with the most efficient approach to create a white LED that has good color quality, high CRI and luminous flux.