Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes

2005 ◽  
Vol 97 (5) ◽  
pp. 054506 ◽  
Author(s):  
S. Chhajed ◽  
Y. Xi ◽  
Y.-L. Li ◽  
Th. Gessmann ◽  
E. F. Schubert
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Junction Temperature ◽  
Light Sources ◽  
Light Emitting ◽  
Color Rendering

scholarly journals Design of highly efficient phosphor-converted white light-emitting diodes with color rendering indices (R1 − R15) ≥ 95 for artificial lighting

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yong Nam Ahn ◽  
Kyu Do Kim ◽  
Gopinathan Anoop ◽  
Gab Soo Kim ◽  
Jae Soo Yoo
Keyword(s):  
Light Source ◽  
White Light ◽  
Light Emitting Diodes ◽  
Light Sources ◽  
High Definition ◽  
Light Emitting ◽  
Artificial Lighting ◽  
Red Phosphors ◽  
White Light Emitting Diodes ◽  
Color Rendering

AbstractPhosphor-converted white light-emitting diodes (pc-WLEDs) are excellent energy-efficient light sources for artificial lighting applications. One goal of artificial lighting is to make objects/images look natural – as they look under the sunlight. The ability of a light source to accurately render the natural color of an object is gauged by the parameter – color rendering index (CRI). A conventional pc-WLED has an average CRI ~ 80, which is very low for accurate color reproduction. To utilize the pc-WLEDs for artificial lighting applications, all the CRI points (R1 – R15) should be above 95. However, there is a trade-off between CRI and luminous efficacy (LER), and it is challenging to increase both CRI and LER. Herein we propose a novel LED package (PKG) design to achieve CRI points ≥95 and efficiency ~100 lm/W by introducing two blue LEDs and a UV LED in combination with green and red phosphors. The silicone encapsulant, the current through the LEDs, and the green/red phosphor ratio were optimized for achieving high CRI and LER. Our re-designed LED PKG will find applications in stadium lighting as well as for ultra-high-definition television production where high CRI points are required for the artificial light source.

53% Efficient Red Emissive Carbon Quantum Dots for High Color Rendering and Stable Warm White‐Light‐Emitting Diodes

2017 ◽  
Vol 29 (37) ◽  
pp. 1702910 ◽  
Author(s):  
Zifei Wang ◽  
Fanglong Yuan ◽  
Xiaohong Li ◽  
Yunchao Li ◽  
Haizheng Zhong ◽  
...  
Keyword(s):  
Quantum Dots ◽  
White Light ◽  
Light Emitting Diodes ◽  
Carbon Quantum Dots ◽  
Light Emitting ◽  
Warm White Light ◽  
White Light Emitting Diodes ◽  
Color Rendering

Sonochemical Synthesis of Carbon Dots/Lanthanoid MOFs Hybrids for White Light-Emitting Diodes with High Color Rendering

2019 ◽  
Vol 11 (47) ◽  
pp. 44421-44429 ◽  
Author(s):  
Jintana Othong ◽  
Jaursup Boonmak ◽  
Vinich Promarak ◽  
Filip Kielar ◽  
Sujittra Youngme
Keyword(s):  
White Light ◽  
Carbon Dots ◽  
Light Emitting Diodes ◽  
Sonochemical Synthesis ◽  
Light Emitting ◽  
White Light Emitting Diodes ◽  
Color Rendering

Four color stacked white organic light-emitting diodes utilizing the concept of triplet harvesting

2011 ◽  
Vol 1286 ◽  
Author(s):  
Th. C. Rosenow ◽  
S. Olthof ◽  
S. Reineke ◽  
B. Lüssem ◽  
K. Leo
Keyword(s):  
Light Emitting Diodes ◽  
Blue Emission ◽  
Organic Light Emitting Diodes ◽  
Light Sources ◽  
Emission Layer ◽  
Light Emitting ◽  
Organic Light ◽  
Blue Emitters ◽  
Color Rendering ◽  
Triplet Harvesting

ABSTRACTOrganic light-emitting diodes (OLEDs) are developing into a competitive alternative to conventional light sources. Nevertheless, OLEDs need further improvement in terms of efficiency and color rendering for lighting applications. Fluorescent blue emitters allow deep blue emission and high stability, while phosphorescent blue emitter still suffer from insufficient stability. The concept of triplet harvesting is the key for achieving internal quantum efficiencies up to 100 % and simultaneously benefiting from the advantages of fluorescent blue emitters. Here, we present a stacked OLED consisting of two units comprising four different emitters in total. The first unit takes advantage of the concept of triplet harvesting and combines the light emission of a fluorescent blue and a phosphorescent red emitter. The second unit emits light from a single emission layer consisting of a matrix doped with phosphorescent green and yellow emitters. With this approach, we reach white color coordinates close to the standard illuminant A and a color rendering index of above 75. The presented devices are characterized by high luminous efficacies of above 30 lm/W on standard glass substrates without outcoupling enhancement.

scholarly journals System efficiency of laser-based white light

2014 ◽  
Vol 3 (5-6) ◽  
Author(s):  
Roland Lachmayer ◽  
Alexander Wolf ◽  
Gerolf Kloppenburg
Keyword(s):  
Thermal Management ◽  
White Light ◽  
High Power ◽  
Laser Diodes ◽  
Light Sources ◽  
System Efficiency ◽  
Light Emitting ◽  
Scale Down ◽  
Color Rendering ◽  
Product Weight

AbstractFor many lighting applications, light-emitting diodes (LEDs) are replacing traditional light sources providing the possibility for smart and efficient systems as well as a reduction in the product weight. A next step in this development is the integration of laser-based light sources to increase luminance and to further scale down the optics possibly leading to a reduction of necessary resources. This article reviews the possibilities and challenges arising from the use of laser diodes especially compared to current high-power LED systems in terms of efficiency, color-rendering properties, and thermal management.

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