My Hanh Nguyen Thi
Industrial University of Ho Chi Minh City

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Journal : TELKOMNIKA (Telecommunication Computing Electronics and Control)

MgCeAl11O19:Tb3+ and Mg8Ge2O11F2:Mn4+ in enhancing the color quality of remote phosphor LED My Hanh Nguyen Thi; Phung Ton That
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.v19i3.14479

Abstract

As the name infers, the triple-layer remote phosphor (TRP) has 3 phosphor layers includes the red Mg8Ge2O11F2:Mn4+ phosphor layer on the top, the green MgCeAl11O19:Tb3+ phosphor layer in the middle, and the yellow YAG:Ce3+ layer at the bottom and is mentioned as a solution to increase the chromaticity and luminescence adequacy of the white LEDs (WLEDs) in this article. As to control the red light for higher value achieve in the color rendering index (CRI), using red Mg8Ge2O11F2:Mn4+ phosphor in the TRP structure is recommended. All the outcomes indicate that when red phosphor Mg8Ge2O11F2:Mn4+ concentration grows the CRI gets higher values, and drastically declines when the concentration of green phosphor MgCeAl11O19:Tb3+ increases. As the same time, applying the green MgCeAl11O19:Tb3+ phosphor layer to manage the green light as it can make the luminous efficacy (LE) of WLEDs increase. In particular, the index of LE can also be improved over 40% by limiting the scatter of light and putting in green light. Moreover, to preserve the average correlated color temperature (ACCT) stable at 8500K, the yellow YAG:Ce3+ concentration must be cut down as the concentration of red and green phosphor rise.
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.