Trends

LpR Article | Technologies | Jun 29, 2016

Optical Lithography Method for Advanced Light Extraction in LEDs

Objective material selection for various target applications is key for successful product development. Efficient light extraction features are crucial for highly efficient LEDs. Thomas Uhrmann and Harun Solak, et.al* from EV Group and Eulitha AG will demonstrate a novel lithography method, PHABLE™, that enables the printing of sub-μm patterns in a non-contact, proximity process. Read more »

LpR Article | Technologies | Jun 28, 2016

High-Index Nanocrystals - Key to Next Generation Advancements in Lighting

Solid-State Lighting is destined to be a next generation lighting option. LEDs have already entered main stream applications and OLED technology has advanced greatly in the past few years in terms of efficacy and performance. Both technologies need to continue to improve performance to achieve high market acceptance. Dr. Gregory Cooper, Chief Technology Officer and Founder of Pixelligent Technologies LLC, illustrates how LED and OLED technology can advance to the next level by incorporating nanomaterials into existing packaging. Read more »

LpR Article | Technologies | Jun 28, 2016

MOCVD Platform for Cost-Effective Production of GaN-based HB LEDs

GaN-based blue and ultraviolet light emitting diodes (LEDs) are steadily becoming more widely used in solid-state lighting (SSL) applications [1-3]. Enabling dramatic energy savings when compared to contemporary incandescent bulbs and fluorescent lamps, these high-brightness LEDs (HB-LEDs) have a market potential in the billions of dollars. Yole Development estimates that by 2017, the market for LEDs will be approximately $75 billion [4, 5]. Shiping Guo, the Senior Technology Director of Advanced Micro-Fabrication Equipment Inc. presents a new approach to support this goal with a cost effective MOCVD solution for HB-GaN LED manufacturing. Read more »

LpR Article | Technologies | Jun 28, 2016

OLED Technology in Lighting Applications

Prototypes and niche applications with OLEDs for lighting have been demonstrated over the past few years. Now there are indications that OLED technology is ready for mass production or at least will be ready very soon. Franco Musiari, Technology Specialist at ASSODEL analyzed the current status and future perspectives of OLED technology. Read more »

LpR Article | Technologies | Jun 28, 2016

LED and Lens Degradation Through Volatile Organic Compounds

In general, LEDs are very resistant light sources. Nevertheless, glues, conformal coatings, o-rings, gaskets, and potting compounds, all materials that are frequently used in the construction of LED based luminaires or lamps and often contain volatile organic compounds (VOCs) may have a negative impact on performance, reliability and lifetime. Edward Steinke, application engineer at Cree, explains the set of problems and how to prevent these issues based on Cree’s products, using their test kit components, as well as components for lamp and luminaire applications. Read more »

LpR Article | Technologies | Jun 28, 2016

Reliability Oriented Design of LED-Based Light Sources

The transition from traditional light sources to SSL systems requires a different design philosophy to achieve the advantages offered by LED light sources. The key approach is based on the parallel design of thermal, electrical, optical and spectral properties of the light source. Matteo Meneghini, Gaudenzio Meneghesso, Enrico Zanoni and Matteo Dal Lago from the Department of Information Engineering at the University of Padova, and Nicola Trivellin from LightCube SRL explain this approach including the importance of the electrical management of LEDs, comparing modulation techniques to constant current, differentiating between versatility and efficiency. Read more »

Technologies | LEDs | Light Conversion | Jun 23, 2016

New Phosphor Promises Cheaper and more Efficient Next-Generation LED Lighting

Researchers from KU Leuven (Belgium), the University of Strasbourg, and CNRS have discovered a new phosphor that could make next-generation fluorescent and LED lighting even cheaper and more efficient. The team used highly luminescent clusters of silver atoms and the porous framework of minerals known as zeolites. Read more »

Technologies | LEDs | Laser | Light Conversion | LiFi | Jun 23, 2016

Perovskite Phosphor Provides High Quality White Light and Boosts VLC

Mark Peplow recently reported on the Chemical & Engineering News website about the latest encouraging research results from a research team from CEMSE and KAUST. The researchers found that combination of solution-processed CsPbBr3 perovskite nanocrystals (NCs) with a conventional red phosphor produces high quality white light when pumped with a blue LED or laser. Furthermore excited-state lifetime is short enough to provide record-breaking high bandwidth for visible light communication (VLC), aka LiFi. Read more »

LpR Article | Technologies | Jun 21, 2016

Safety Issues for LED Drivers with PWM Operation Modes by Product Approvals Ltd.

In many cases LED drivers manage their output power with PWM controlled switched mode power supply-topologies. The output voltages are filtered and normally DC voltages with low ripple apply at the output connectors of LED drivers. During dimming these circuits can behave very differently and therefore safety issues may arise. Siegfried Luger, CEO at Luger Research e.U. and John Showell, Product Safety Consultant at Product Approvals Ltd. have a closer look at those operation modes and the requirements on voltage limits. Read more »

LpR Article | Technologies | Jun 21, 2016

Optimization of SSL LED Devices by Osram Opto Semiconductors

There are different levers to improve LED performance. Ralph Bertram, application engineer for SSL products, and Alexander Wilm, key expert in the SSL application engineering department at Osram Opto Semiconductors, have a look into the device itself and explore the principal limitations of the different contributors to device efficacy. They show how to balance driving current and chip size to define the right LED, and explain the impact on performance and system costs of LED packages for the intended lighting task approaches for lighting strategies. Read more »

LpR Article | Technologies | Jun 20, 2016

LED Light Spectrum Enhancement with Transparent Pigmented Glazes

While LED bulbs have the distinct economic advantages of using less energy, producing less heat and lasting years longer than traditional incandescent bulbs, when objects are viewed under LED light, they frequently appear to be of different colors than when viewed in sunlight or with incandescent lights. Jan-Marie A Spanard from Light Spectrum Glazes proposes and explains an approach to optimize the spectral distribution of LED light to overcome this weakness. Read more »

LpR Article | Technologies | Jun 20, 2016

High Color-Rendering, Full-Visible-Spectrum LEDs by Soraa

The first wave of conventional white LEDs primarily focused on lumens per Watt. These LEDs were based on phosphor down-conversion using primary blue “pump” emission. Currently LEDs are catching up in regards to light quality using different approaches. Aurelien David, Senior Principal Scientist and Mike Krames, Chief Technology Officer at Soraa explain their technology approach of violet-pumped, full-visible-spectrum LEDs, and the interrelated challenges and advantages. Read more »

Research | Jun 09, 2016

Blue Wavelengths of LED Light Negatively Affect Milk Quality

Matt Hayes, managing editor and social media officer for the College of Agriculture and Life Sciences, and Alina Stelick, research support specialist in the Department of Food Science, report at the Cornell Chronicle of June 8th, 2016 that Cornell researchers in the Department of Food Science found exposure to light-emitting diode (LED) sources for even a few hours degrades the perceived quality of milk more so than the microbial content that naturally accumulates over time. Their study determined milk remained at high-quality for two weeks when shielded from LED exposure, and consumers overwhelmingly preferred the older, shielded milk over fresh milk stored in a typical container that had been exposed to LED light for as little as four hours. Read more »

LpR Article | Technologies | Jun 08, 2016

InGaN Nanowires Make Light Mixing Efficient and Smart

The correlated color temperature (CCT) of high color rendering index (CRI) LED lighting systems can, in principle, be tuned over a wide range. As an alternative approach to conventional phosphor based LEDs, a full-color LED array consisting of red, green and blue (RGB) InGaN based nanowire LEDs monolithically integrated on a micro-scale level has been proposed and fabricated. J. Lee from the Nano Electronics Lab at the Samsung Advanced Institute of Technology, Renjie Wang, Hieu P. T. Nguyen, Ashfiqua T. Connie, Ishiang Shih, and Zetian Mi from the Department of Electrical and Computer Engineering at McGill University in Montreal explain how this technology works and how the three multi-color subpixels on the same chip can be separately biased and can exhibit full-color emission which can be tuned controllably in a wide CCT range. Read more »

LpR Article | Research | Jun 08, 2016

A Graphene-Based, Spectrally Tunable, Flexible Field-Effect Light-Emitting Device by the Tsinghua University and the Tsinghua National Laboratory for Information Science and Technology

The continuous tuning of the emission spectrum of a single light-emitting diode (LED) by an external electrical bias is of great technological significance as a crucial property in high-quality displays and may be used in high quality lighting applications, yet this capability has not been demonstrated in existing LEDs. Graphene, a tunable optical platform, is a promising medium to achieve this goal. Xiaomu Wang, He Tian, Mohammad Ali Mohammad, Cheng Li, Can Wu, Yi Yang, and Tian-Ling Ren from the Institute of Microelectronics at the Tsinghua University in Beijing and the Tsinghua National Laboratory for Information Science and Technology (TNList) demonstrate a bright spectrally tunable electroluminescence from blue (~450 nm) to red (~750 nm) at the graphene oxide/reduced-graphene oxide interface. Read more »

LpR Article | Technologies | Jun 08, 2016

Mastering Thermal Issues in LED PCB Design & Laminate Selection by Ventec Europe

LED applications are not the only applications that are driving the need for thermal issues to be considered and mastered in PCB design, but they are certainly amongst the most challenging. Designing LED PCBs requires many considerations and key are those that arise from multiple heat sources in close proximity. Martin Cotton, Director OEM Technology of Ventec Europe describes the process and criteria used when designing PCBs (Printed Circuit Boards) for use in LED applications using thermally conductive IMS (Insulated Metal Substrates). He goes into technical detail with charts and diagrams that explain everything the designer would need to consider when selecting a laminate and commencing a design. Read more »

LpR Article | Research | Jun 07, 2016

Al2O3 Coated Europium- Activated Aluminum Silicon Nitride for COB LED Technology by the Graz University of Technology and Tridonic Jennersdorf

Eu2+ activated nitride phosphors have drawn much interest for solid state lighting because of their interesting photoluminescence. While they show excellent optical properties, they are hygroscopic and have the potential of being degraded by atmospheric moisture and high temperatures. A coating layer on the surface is an effective method to improve stability against moisture and oxidation. For use in chip on board technology, Nika Mahne, master student at the Institute of Inorganic Chemistry, A. Reichmann, B. Bitschnau, R. Fischer, from the Graz University of Technology, and F. Schrank from Tridonic Jennersdorf propose an approach where a CaAlSiN3:Eu2+ [1, 2, 3] phosphor was coated with Al2O3, obtained via a Brønsted precipitation reaction based on a solution-coating process from a mixture of aluminum halide with a base after annealing at a temperature of 400°C. Read more »

LpR Article | Technologies | Jun 07, 2016

New Class of Siloxane Polymers for Advanced LED Packaging

Packaging presents a major challenge to further improve LED device efficiency and reliability. A novel class of high stability siloxanes forms a technology platform to address such opportunities in die attach, encapsulation, and light outcoupling applications. Dr. Juha Rantala, CEO & Founder, Dr. Joerg Rockenberger, Director Application & Business Development, Dr. Jyri Paulasaari, Vice President Technology, Dr. Jarkko Heikkinen, Director Inks & Pastes. Markus Laukkanen, Application Manager, and Dr. Janne Kylmä, Vice President Engineering & Production at Inkron Oy explain the material properties and give examples of how these new materials in combination with novel nanomaterials enable products fully compatible with current process tools and flows while having superior properties. Read more »

LpR Article | Research | Jun 07, 2016

Flexible OLEDs for Lighting Applications by the Holst Centre

While OLEDs already have successfully found their way into display applications, the breakthrough in lighting applications is still pending. The reasons are diverse, but cost is one major point. Another reason is the current edge of inorganic LEDs giving reasonable design opportunities in many standard applications. However, there are applications where OLEDs could score, especially the flexible OLEDs. But even these OLEDs need to become cheaper to be applied widely. The Holst Centre and partners aim to develop generic technologies for large area flexible OLEDs which can be processed with roll-to-roll (R2R) technology. Process Engineer Tansim Baig gives an example and an overview of the current status of the development. Read more »

LpR Article | Trends | Jun 06, 2016

Embedded Lighting - Developing New Lighting Applications for Modern Architectural Projects by Philips Lighting

When the era of LED lighting started, everybody talked about the new age of lighting with new opportunities. While many lighting concepts are still pure replacements of the conventional light sources, with the maturation of this technology, more and more new concepts are realized, and the future perspectives are even more exciting. Brad Koerner, Venture Manager - Philips Luminous Patterns at Philips Lighting, shows examples, explains why such new concepts are desirable, and discusses which technologies support the introduction of new lighting applications. Read more »

LpR Article | Research | Jun 03, 2016

Luminescent Glasses and Glass Ceramics for White Light Emitting Diodes by the Fraunhofer Institute and the South Westphalia University of Applied Science

Luminescent glasses or glass ceramics represent an interesting alternative to LED phosphor due to their high thermal and chemical stability. A series of rare-earth doped glasses are investigated for their potential application as photon converters for solid-state lighting applications. Franziska Steudel, Sebastian Loos, Bernd Ahrens, and Stefan Schweizer from the Fraunhofer Institute and the South Westphalia University of Applied Science respectively, show that the color coordinate of double-doped glass can be varied over a broad spectral range by changing the rare-earth doping ratio accordingly. In addition, double-doping allows for a change in the color coordinate by using different excitation wavelengths. Read more »

LpR Article | Technologies | Jun 03, 2016

Cost and Performance Optimization of Thermal Management Solution for High Power LEDs by Cambridge Nanotherm

The LED industry has a challenge. General lighting requires very bright LEDs that can replace incandescent and halogen lights. Manufacturers need efficacy, cost and manufacturability to be “just right” but most leading solutions, especially in thermal management, are short of the mark. Giles Humpston, applications engineer, Cambridge Nanotherm, discusses ways to combine performance with reasonable costs and good manufacturability. Read more »

Resources | LpR Article | Event-Reports | Trends | May 30, 2016

Light + Building Post Show Report: The Six Most Noteworthy Observations by LED professional

In the weeks and months before the show it was obvious that the major topics were going to be IoT and connectivity. There are many reasons for this. One is that LED lighting has become established but the big deals for smart lighting and human centric lighting are missing. IoT seems to be the way to improve communication and enable both smart lighting and HCL. Arno Grabher-Meyer from LED professional gives a summary of his impressions of the fair in regards to these topics, and beyond. Read more »

LpR Article | Research | May 24, 2016

Thin-Film Light Management System for Intelligent Large-Area LED Luminaires by the Centre Suisse d’Electronique et de Microtechnique SA

The recent advances in Solid State Lighting have triggered the development of smart lighting solutions. However, the point-like nature of LEDs imposes the use of inefficient and/or bulky light scattering sheets or costly, short-pitch LED arrays to achieve acceptable spatial luminance uniformity. Ph.D. Oscar Fernandez, Senior R&D Engineer at the Centre Suisse d’Electronique et de Microtechnique SA (CSEM) shows a new approach in the form of an innovative thin form-factor light management (LM) system comprising a highly engineered combination of thin-film diffractive nano-optical and refractive micro-optical elements. Read more »

Resources | Fundings | EU-Calls | Technologies

EU Call: FET-Open Research and Innovation Actions

This call is open for any kind of research on future and emerging technologies (FET) in early stages. Proposals should cover high-risk, interdisciplinary research on radically new technologies. Read more »

LpR Article | Technologies | May 24, 2016

Create Colorful and Bright LED Light with an LED Matrix Dimmer by Linear Technology

RGB LEDs are quite common and used in many applications today. More advanced multi-color solutions like RGBW, RGBA or RGBWA offer huge advantages over RGB solutions, but several aspects are more complicated. Keith Szolusha, applications engineering section leader for power products at Linear Technology explains the advantages of RGBW systems, how they work, how to set up such systems, and how to drive them correctly using Linear Technology’s LT3965 8-switch LED matrix dimmer in combination with the LT3952 boost-buck LED driver as an example. Read more »

Technology | May 20, 2016

LED Lighting: All Eyes on Flicker by Tridonic

Flicker was a familiar problem with early fluorescent lamps. However, increasingly powerful electronic control gear has largely offset these interferences over time, banishing them from current perception. Since LEDs (light-emitting diodes) have become established in all areas of lighting, including general lighting, flicker has reemerged. LED Drivers play a key role in producing light that is as flicker-free as possible. Read more »

LpR Article | Technologies | May 19, 2016

3-Pad LED Flip Chip COB by Flip Chip Opto

Wafer level packaging and flip chip design are the most recent trends in LED manufacturing and packaging. These LED types are perfectly suited for producing COB modules. This combination already promises better thermal performance than standard SMD package based products. However, there is still room for improvements. Pao Chen, Director of Research and Development at Flip Chip Opto shows how a 3-pad flip chip LED further reduces thermal resistance, allows higher power and can help to reduce costs. Read more »

LpR Article | Research | May 17, 2016

Human-Focused Outdoor Illumination: Trade-Off Between Pleasing Color and Circadian Action, by the Vilnius University

A smart RGBA solid-state light engine with tunable correlated color temperature (CCT) and high-fidelity color rendition was applied for the validation of the Kruithof hypothesis in several outdoor environments. Subjects were asked to find the most “pleasing” illumination conditions by performing a CCT adjustment. Maintaining constant illuminance, the mean selected CCT was found to increase from about 3000±200 K at 5 lx to about 3500±250 K at 50 lx almost independently of the content of the viewed scene. Dr. Pranciškus Vitta, Head of Lighting and Electronics System Lab at the Vilnius University shows that this increase is statistically significant and provides qualitative validation of the Kruithof hypothesis in outdoor environments, but with the intervals of CCT for “pleasing” illumination, it is substantially broader and shifted to higher values. Read more »

Technologies | OLEDs | Light Conversion | May 13, 2016

Research on OLEDs with Ultrathin Emissive Layers and a Spacer-Free Structure

Since C.W Tang demonstrated the first organic light-emitting diodes (OLEDs) based on a double-layer structure of organic materials in 1987, flat-panel displays and lighting applications based on OLED technology have grown dramatically because of their attractive features such as ultra-thin structure, light-weight and flexibility. To achieve a desirable OLED performance, a host-dopant system is adopted. This not only leads to an increase in material cost and device processing time, but also makes it difficult to control dopant concentration accurately. Therefore, OLEDs with dopant-free and ultrathin emissive layers (UEMLs) have aroused much attention. Shengfan Wu, Sihua Li, Qi Sun, Chenchao Huang & Man-Keung Fung recently published the results of their research on such ultrathin emissive layers (UEMLs) of phosphorescent materials for OLED applications. Read more »