Improving luminous flux and color homogeneity of dual-layer phosphor sctructure

Anh³

2020

TELKOMNIKA

Lighting devices that apply diodes to create white light-emitting diodes (WLEDs) can achieve remarkable results in color quality, especially those containing quantum dots (QDs) and phosphor. The technique to create an appropriate package is providing spaces between the QDs and phosphor components which helps decrease the ratio of the reabsorption losses and keeps the QDs surface ligands constant. The research aims to perfect the constructing method of remote phosphor configuration containing quantum dots and phosphor materials that based on lighting properties and temperature feature of WLEDs. The infrared thermography is the tool to measure and analyze total emitted light and emission ranges of the device. This device is also used in temperature simulation and experimental verification. At the given mA of 60, the WLEDs structure with green QDs layer above the phosphor layer results in 996 lm luminous flux (LF), and Ra = 57 in color rendering ability. Meanwhile, luminous flux of WLEDs with red QDs-on-phosphor structure is 632, and Ra = 70. Furthermore, comparing with the green QDs-onphosphor type, the red QDs-on-phosphor type emitted less LF. However, the red QDs-on-phosphor type can be the most effective package design to achieve color rendering ability.

Section: Introductionmentioning

confidence: 99%

Acquiring higher lumen efficacy and color rendering index with green NaYF4:Er3+Yb3+ and red α-SrO·3B2O3:Sm2+ layers for designing remote phosphor LED

Thi

Anh³

2020

TELKOMNIKA

“…In the dual-layer phosphor configuration, yellow phosphor is lower, upper is red phosphor or green phosphor [16][17][18]. In the triple-layer phosphor configuration, yellow phosphor is lower, red phosphor is upper, and green phosphor is middle.…”

Section: Introductionmentioning

confidence: 99%

Improving color quality and luminous flux of white LED utilizing triple-layer remote phosphor structure

Anh

2020

IJECE

Self Cite

In this manuscript, we presented a research that enhance the performance of WLED using the multi-phosphor configuration. The phosphor layers in the research are separated from each other to achieved better luminous efficiency, however, it makes controlling color light quality more complex. Another issue is finding out the whether two layers of phosphor or three layers of phosphor is better in improving color quality. The research addressed this issue by analyzing the optical aspects of the respective WLEDs that employ these structure. The studied aspects are quality indicators such as luminous efficacy (LE), and color uniformity, color rendering index (CRI), color quality scale (CQS). The results of the experiments in this research, which come from the employment of WLEDs with 2 color temperatures 5600 K and 8500, suggest that WLED with three phosphor layers is better in CRI, CQS, LE. This type of phosphor structure also limits the color deviation significantly, thus, improves the color uniformity. This results is verifies with Mie theory, therefore, can be applied as reference or guideline for production of better WLEDs

“…However, those studies only concentrated on the WLEDs configurations with a single chip and at low correlated color temperatures while a more difficult task is to improve the optical properties of WLEDs with high correlated color temperatures. As acknowledging this important goal, Anh and his partners have conducted two different researches demonstrating the how the application of double layers of phosphor in WLEDs can influences the quality indicators, specifically on lumen output and color uniformity [16][17][18]. In the first study, the dual-remote phosphor with flat layers (FDRP) were compared with concave dual-remote phosphor (CDRP) to figure out which is more advantageous to WLEDs packages.…”

Section: Introductionmentioning

confidence: 99%

The application of double-layer remote phosphor structures in increasing WLEDs color rendering index and lumen output

Anh

2020

IJECE

Self Cite

The remote phosphor structure often has inferior color quality but better luminous flux in than conformal or in-cup configurations. Therefore, numerous researches study remote phosphor structure for methods to enhance it chromatic quality. This study introduces the use of dual-layer remote phosphor structure in WLEDs with identical structure but at different color temperature, 6600K and 7700K, to demonstrate their effect on quality indicators. The concept is placing a green phosphor layer (Ce,Tb)MgAl11O19:Ce:Tb or a red phosphor layer MgSr3Si2O8:Eu2+,Mn2+ on the layer of yellow-emitting phosphor YAG:Ce3+ and find the suitable concentration of the additional phosphor to create the best color quality. The results showed that the increase of CRI and CQS are affected by MgSr3Si2O8:Eu2+,Mn2+, in particular, the higher the concentration of red phosphor gets the better CRI and CQS because the emitted red light in enhanced. The green phosphor layer (Ce,Tb)MgAl11O19:Ce:Tb, on the other hand, is beneficial for the luminous flux. The concentration of MgSr3Si2O8:Eu2+,Mn2+ and (Ce,Tb)MgAl11O19:Ce:Tb, however, need to be adjusted properly to avoid decreasing the luminous flux due to overgrowth. The Mie scattering theory and Beer’s law are the verification tools for these conclusions, which gives them the credibility to be applied in producing better quality WLEDs.