LEDs & OLEDs

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. Read more »

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. Read more »

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. Read more »

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. Read more »

Resources | Tech-Talks Bregenz | Laser Technology | Dec 16, 2019

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. Read more »

Featured | LEDs | Cree | Dec 02, 2019

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. Read more »

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. Read more »

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. Read more »

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. Read more »

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. Read more »

LEDs | Solar Systems | Technologies | Jun 04, 2019

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. Read more »

Technologies | LEDs | Monolythic RGB LEDs | Color-Tuning | May 02, 2019

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. Read more »

Technologies | Light Conversion | Phosphors | White LEDs | Apr 24, 2019

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. Read more »

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. Read more »

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. Read more »

The Possible Future of Lighting - Paint-On Semiconductors from Ornate Quantum Physics

LED lights and monitors, and quality solar panels were born of a revolution in semiconductors that efficiently convert energy to light or vice versa. Now, next-generation semiconducting materials are on the horizon, and in a new study, researchers have uncovered eccentric physics behind their potential to transform lighting technology and photovoltaics yet again. Read more »

Colloidal Quantum Dots Make LEDs Shine Bright in the Infrared

ICFO researchers report on the development of a colloidal quantum-dot light emitting diode with unprecedented quantum and power conversion efficiencies in the infrared range. The ideal optoelectronic semiconductor material should be a strong light emitter i.e. should emit light very efficiently upon optical excitation as well as be an efficient charge conductor to allow for electrical injection in devices. These two conditions when met can lead to highly efficient light emitting diodes as well as to solar cells with the possibility to approach the Shockley-Queisser limit. Until now the materials that have come close to meeting these conditions have been based on epitaxially-grown costly III-V semiconductors that cannot be monolithically integrated to CMOS electronics. Read more »

Researchers Push Perovskite LEDs' Efficiency To Rivaling Best OLEDs

Compared to OLEDs, which are widely used in high-end consumer electronics, the perovskite-based LEDs, developed by researchers at the University of Cambridge, can be made at much lower costs, and can be tuned to emit light across the visible and near-infrared spectra with high colour purity. Now, researchers have set a new efficiency record for LEDs based on perovskite semiconductors, rivalling that of the best Organic LEDs (OLEDs). Read more »

New Algorithm Can More Quickly Predict Phosphor Materials for LEDs

Jakoah Brgoch, assistant professor of chemistry at the University of Houston, and members of his lab published a paper on Oct. 22 in Nature Communications describing how machine learning speeds discovery of new materials. By scanning a huge number of compounds for their key attributes they were looking for a new light conversion material that could be used in white LEDs. Read more »

Laser Technology for Lighting Applications: A Review and Analysis of a Promising Technology

LpR 68 Article, page 44: LEDs are currently the dominating light source: efficient and cost effective. But LEDs also have some drawbacks. Another interesting technology developed slowly in the shadow of LEDs and has become an interesting solution for some specific applications: GaN based blue solid state laser devices. Although this technology offers some very interesting advantages, it also has challenges. Nicola Trivellin, Matteo Buffolo, Carlo De Santi, Gaudenzio Meneghesso, Enrico Zanoni and Matteo Meneghini from the University of Padova and its spin-off LightCube have been working toward the development of experimental systems and demonstrators and disclose their findings of the comparison between LED and LD systems. Read more »

Spanish Researchers Develop Sand that Produces White Sun-Like LEDs

The team led by the chemist-technologist Rubén Costa of IMDEA Materials (Madrid) and the chemists Jesús Berenguer of the University of La Rioja and Javier García of the University of Alicante has overcome one of the biggest obstacles in the progress towards new sources of healthier artificial lighting. Read more »

Dynamic In-Car Lighting Scenarios - Osram's Osire E4633i Prototype with Inova's Serial Control Driver

The more autonomous a car becomes, the more the way in which it is used will change. As developments continue toward autonomous driving, more and more attention is being focused on the passenger cell. Light will become an integral part of the passenger cell, taking on functional and design-specific tasks. Previously static light, which could only be switched on and off, has now been given a dynamic dimension with the prototype of the Osire E4633i – with countless design options for car manufacturer. Read more »

Electron Beam Patterning for Full-Color HR OLED Displays

OLED microdisplays are increasingly establishing themselves in consumer-ready wearables and data glasses. In order to meet the requirements for higher efficiency, higher contrast, and higher resolutions in these applications, Fraunhofer FEP scientists have developed a new micropatterning approach for OLEDs on silicon substrates. This might eliminate the use of color filters and shadow masks in the future and allow full-color displays to be developed by means of a new process. An increase in efficiency and considerably broader color gamut have already been demonstrated in first experiments. Read more »

Electrical Over Stress - How to Prevent an LED Failing Earlier than Expected

Article from LpR 66, page 70: While LEDS are, in general, very robust, failures still happen due to electrical over stress. Mauro Ceresa, EMEA Field Application Engineer Manager at Cree, will cover all aspects related to electrical over stress, or when an LED fails due to being subjected to a voltage beyond its specification limits. He will explain why the failure occurs and how to prevent this from happening. The article will explain the fundamental aspects of a good PCB layout design and how this is linked to the longevity of an LED. Read more »

Liquid-Suspended White QD LEDs Achieve Luminous Efficacy Record

Quantum dot (QD) white LEDs that show a luminous efficacy of 105 lm/W have been developed. The QDs are liquid-based and, according to researchers, could help the LEDs achieve an efficacy double that of LEDs that incorporate quantum dots in solid films. With further development, researchers say the new LEDs could reach an efficacy over 200 lm/W. Read more »

Technologies | Research Reports | LEDs | Manufacturing | Jul 12, 2018

InteGreat Project Successfully Researched New Approaches to LED Production

In the InteGreat research project, Osram Opto Semiconductors coordinated a consortium comprising seven partners from science and industry. Between December 2014 and February 2018 the project partners investigated time-honored manufacturing approaches and know-how along the entire LED production process with the aim of identifying potential areas for optimization. The new insights allow for LED products to be given additional superior properties that would have been difficult or even impossible to achieve with the technologies previously used to produce LEDs. Read more »

A Near Infrared Enhanced LED Lighting Approach

With the evolution of LED lighting, one topic has come more and more in the focus of the lighting industry: Human Centric Lighting (HCL). While HCL is not clearly defined, a common understanding is that this is light and lighting that supports health and the well-being of humans. Some new proposals are going beyond the approach of providing just visible light in adequate quality, but also to providing invisible radiation, UV and/or NIR that support health and well-being. Some research and the evolution of humans show clear evidence for positive effects of this kind of illumination. Scott Zimmerman, CEO at Silas, presents a new approach that adds NIR radiation to LED illumination. He explains the background of this idea, how it also improves the quality of visible light and discusses the health benefits. Read more »

Full-Color InGaN/AlGaN Nanowire Light-Emitting Diodes for SSL and Displays

III-nitride based nanowire light-emitting diodes (LEDs) have received a staggering response as a future candidate for solid-state lighting and full-color displays due to their unique and exceptional features including drastically reduced polarization fields, dislocation densities as well as the associated quantum confined Stark effect (QCSE) on account of their effective strain relaxation. Moab Rajan Philip and his supervisor Dr. Hieu P Nguyen in the Nano-Optoelectronic Materials and Devices Laboratory at the New Jersey Institute of Technology (NJIT) present astonishing ideas to fabricate and control the color emission of III-nitride nanowire LEDs via molecular beam epitaxy (MBE) growth techniques. The advantage of such LEDs and their characteristics is also discussed. Read more »

KAIST Team Develops Flexible Blue Vertical Micro LEDs

In CES 2018, micro LED TV was spotlighted as a strong candidate for replacing the active-matrix organic light-emitting diode (AMOLED) display. Micro LED is a sub-100 um light source for red, green and blue light, which has advantages of outstanding optical output, ultra-low power consumption, fast response speed, and excellent flexibility. Professor Keon Jae Lee from the Department of Materials Science and Engineering and his team have developed a low cost production technology for thin-film blue flexible vertical micro LEDs (f-VLEDs). Read more »

Smart Printing: Fraunhofer IAP Develops Power Generating Films and Luminescent Glass

New inks for inkjet printers make it possible to print organic displays or solar cells on film and glass for the use in architecture, the textile industry and many other industries. Read more »