Adopting an LED More Suited to Circadian Entrainment
Since the introduction of LED lights, a lot has been said about risks of blue light for ocular health on the one hand, and the opportunity of circadian entrainment, on the other hand. While a controversial discussion on the first topic is ongoing, the second topic is well accepted. To solve both issues, Bill Chan, President of LiteController Inc. proposes the application of 465-470nm pumped phosphor converted white LEDs with a content of 86% - 92% blue-turquoise light and 8% - 14% blue-violet light. In the article he concentrates on the second topic and proves the benefit of regulating the circadian entrainment more efficiently, maintaining a high typical efficacy of 150 lm/W and good color rendering of CRI 80+ ideally supporting the WELL Building Standard.
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Hermetic Polymer-Free White LEDs for Harsh Environments
AlGaInN-based white LED can easily achieve lifetimes of up to 100,000 h depending on junction temperature and current density. However, state of the art silicone encapsulated LEDs with powder-based phosphors reveal a strong dependence of field lifetimes on environmental conditions such as humidity, corrosive gas and air pollutant exposure. Dr. Michael Kunzer, Group Leader LED Modules at Fraunhofer Institute for Applied Solid State Physics and his colleagues, Ralf Schmidt, Andreas Zibold, Vasileios Georgiou-Sarlikiotis, Michael Arnold and Isabel Kinski propose luminescent ceramics as an interesting alternative to polymer-dispersed phosphors. This provides entirely new opportunities for the manufacturing of white LEDs. The authors explain the properties and advantage of this hermetic, light converting cap material and how to completely avoid polymers.
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ENABLED – A New Funded Research Program to Design Fluorescent Proteins for White LEDs
A joint research project between Spain, Italy and Austria will work to replace inorganic phosphor filters in LEDs by those nature uses deed down the sea. The ENABLED project, coordinated by the Spanish research center IMDEA Materials Institute, has a budget of € 2.7 million euros, will run for the next 3 years and is funded by the European Commission under the Future and Emerging Technologies programme.
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CIE Announces Availability of New Documentation: Test Method for OLED Luminaires and OLED Light Sources
The new CIE International Standard S 025-SP1/E:2019 is a supplement to CIE S 025:2015 Test Method for LED Lamps, LED Luminaires and LED Modules specifies the requirements for measurement of electrical, photometric, and colorimetric quantities of OLED luminaires and OLED light sources. These sources were not covered by CIE S 025:2015 even though they are very similar in regard to the measurement techniques. Recent improvements in the technology and availability of OLED-based lighting products raised the necessity to extend CIE S 025:2015 to OLED products.
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Tech-Talks BREGENZ - Julian Carey, Marketing Manager at SLD Laser
In 2016, Nobel Laureate, Professor Shuji Nakamura held a key note speech at LpS. As the founder of Soraa and SLD Laser, he named laser lighting as the next, innovative step and disruption in lighting. He emphasized the need to focus on light quality and the tailoring of LED lighting to the natural needs of humas, providing light that mimics sunlight as closely as possible. It was therefore self-evident that LED professional would invite Julian Carey, the Product and Technical Marketing Manager at SLD Laser, for a Tech-Talk when he was at the LpS 2018 in Bregenz. We asked him for an update on the status of laser lighting, business strategies and future prospects and how laser lighting has developed since Professor Nakamura's statements in 2016.
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J Series 5050 New P Class Versions Deliver Industry-Leading Efficacy at 1W
J Series™ LEDs extend Cree’s industry-leading portfolio of lighting-class LEDs to a broader set of applications. The J Series 5050 LEDs combine high efficacy and excellent value in a reliable package.
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Chinese Researchers Propose Method to Overcome Low Efficiency of High-Power Flip-Chip LEDs
Chinese scientists from different research centers recently published a co-authored paper on "Highly Efficient GaN-based High-Power Flip-Chip LEDs" in Optics Express Vol. 27, Issue 12, pp. A669-A692 (2019)under the terms of the OSA Open Access Publishing Agreement. High-power flip-chip light-emitting diodes (FCLEDs) suffer from low efficiencies because of poor p-type reflective ohmic contact and severe current crowding, they propose an improvement by using an Ag film.
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Plessey - Native Blue and Native Green Emission microLEDs from the same Wafer
Plessey, an embedded technologies developer at the forefront of microLED technology for augmented and mixed reality (AR/MR) display applications has extended the capability of their proprietary GaN-on-Silicon process to enable Native Blue and Native Green emission from the same wafer.
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High Performance from Extraordinarily Thick Organic Light Emitting Diodes with Perovskite Layers
By combining thin organic layers with thick layers of hybrid perovskite, researchers at Kyushu University in Japan have developed micrometer-thick organic light-emitting diodes that could improve the affordability and viewing angles of high-performance displays and televisions in the near future.
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Circadian-Friendly Light Emitters: From CCT-Tuning to Blue-Free Technology
Common levels of blue radiation are sufficient to disrupt the circadian cycle, calling for blue-depleted emitters in the evening. Most current solutions employ low-CCT and suffer from poor light quality. Aurelien David, chief scientist at Soraa explains the melanopic lumen and its possible sources of inaccuracy related to the uncertainty in assessing the circadian action spectrum. In addition, he also discusses the concept of a blue-free emitter with minimal melanopic lumen at very low CCT and how such a spectrum providing a good light quality can be optimized.
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Organic Solar Cells and Light-emitting Diodes United
In the past 25 years of research on organic semiconductors, it was thought that organic solar cells and organic light-emitting diodes (OLEDs) could not be combined in a single device. A team of physicists headed by Prof. Koen Vandewal from Technische Universität Dresden has now succeeded in manufacturing an organic solar cell that simultaneously functions as an efficient OLED. Their findings were recently published in the internationally renowned journal Nature Materials.
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Controlling Current, Duty Cycle and Pulses Allows Color Tuning in Monolithic GaN LEDs
A new technique - the result of an international collaboration of scientists from Lehigh University, West Chester University, Osaka University and the University of Amsterdam - could pave the way for monolithic integration for simple color tuning of a light bulb, according to Volkmar Dierolf, Distinguished Professor and Chair of Lehigh's Department of Physics who worked on the project.
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Energy-Saving New Red LED Phosphor Developed at University of Innsbruck
The human eye is particularly sensitive to green, but less sensitive to blue and red. Chemists led by Hubert Huppertz have now developed a new red phosphor whose light is well perceived by the eye. This increases the light yield of white LEDs by around one sixth, which can significantly improve the energy efficiency of lighting systems.
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TU Vienna - New Method to Generate Light from Exotic Particle States
A new type of light-emitting diode has been developed at TU Wien. Light is produced from the radiative decay of exciton complexes in layers of just a few atoms thickness.
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An Old Story Re-Edited? - Firefly-Inspired Surfaces Improve LED Efficiency
A new type of light-emitting diode lightbulb could one day light homes and reduce power bills, according to Penn State researchers who suggest that LEDs made with firefly-mimicking structures could improve efficiency.
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