The Kynix Blog - LED

A safety monitoring method called On-Site Visualization has been implemented in metro system construction sites in Jakarta, Indonesia as part of a Japan International Cooperation Agency (JICA) project. On-Site Visualization (OSV), as its name suggests, is a real-time data processing technology used to check safety levels at construction sites. A device with built-in LEDs is attached to walls and pillars at the building site and measures any irregularities or tilting. The LEDs light up like traffic lights to indicate the danger level with different colors: blue for "no irregularities", and yellow and red for "danger of collapse". This clear method of representation is important in countries with low literacy rates.The JICA project, titled Economic and Social Development Support in Developing Countries through Partnerships with the Private Sector, had participants from multiple private organizations in the OSV Consortium (an industry-academic collaborative group that promotes use of OSV technology). Professor Akutagawa oversaw the technology use. The teams monitored safety levels using OSV for a fixed period at three metro system building sites in the center of Jakarta (two stations in the city center and an elevated track in the south). Following this, they held a seminar presenting the results of the implementation. The project was evaluated highly by the head of construction at Jakarta MRT, who stated that "We can now expect higher standards of safety management".In many developing countries, an increase in public works is accompanied by a sharp rise in the number of accidents, and there is a growing need for safety monitoring. "I want to build a human network that combines know-how from different fields to improve levels of safety and security" commented Professor Akutagawa.Reference:LM324MMLM2710LM3080 

New research by scientists from the University of Bristol has revealed that domestic LED lights are much less attractive to nuisance insects such as biting midges than traditional filament lamps.The team now highlights the urgent need for further research on other heat-seeking flies that transmit disease, including mosquitoes that are carriers of pathogens that cause damaging diseases such as malaria and Zika fever.The study, funded by the Natural Environment Research Council and UK lighting manufacturer Integral LED, used customised traps at 18 field test sites across south-west England, illuminated by a series of LED, filament and fluorescent light sources. Over 4,000 insects were carefully identified. The results showed that LEDs attracted four times fewer insects compared with the traditional incandescent lamps, and half as many as were attracted to a compact fluorescent lamp.Notably, for biting flies (midges in the genus Culicoides, some species of which are vectors of wildlife disease), 80 percent were attracted to the filament lamp, 15 percent to the compact fluorescent and only 2-3 percent to each of the two different LED lamps.Dr Andy Wakefield led the field research in a project supervised by Professors Gareth Jones and Stephen Harris from the University's School of Biological Sciences.  Dr Wakefield said: "We were surprised by the number of biting flies drawn to the traditional tungsten lights. We do not know why this is but we know that some insects use thermal cues to find warm-blooded hosts in the night, so perhaps they were attracted to the heat given off by the filament bulb."Co-sponsors of the study, Integral LED were instrumental in the commissioning of the project and provided technical and financial support.The UK company's Marketing Director Sanjiv Kotecha said: "As lighting manufacturers, we welcome that a link between LED lights and low attraction to insects has been proven. The energy saving advantages of solid-state lighting are well known, yet the benefits to well-being are only beginning to be revealed."Reference:ASMT-UYBG-NACJ8XRCWHT-L1-0000-004E6LUWCP7P-KTLP-5E8G-35-Z  

Use of copper as a fluorescent material allows for the manufacture of inexpensive and environmentally compatible organic light-emitting diodes (OLEDs). Thermally activated delayed fuorescence (TADF) ensures high light yield. Scientists of Karlsruhe Institute of Technology (KIT), CYNORA, and the University of St Andrews have now measured the underlying quantum mechanics phenomenon of intersystem crossing in a copper complex. The results of this fundamental work are reported in the Science Advances journal and contribute to enhancing the energy efficiency of OLEDs.  Organic light-emitting diodes are deemed tomorrow's source of light. They homogeneously emit light in all observation directions and produce brilliant colors and high contrasts. As it is also possible to manufacture transparent and flexible OLEDs, new application and design options result, such as flat light sources on window panes or displays that can be rolled up. OLEDs consist of ultra-thin layers of organic materials, which serve as emitter and are located between two electrodes. When voltage is applied, electrons from the cathode and holes (positive charges) from the anode are injected into the emitter, where they form electron-hole pairs. These so-called excitons are quasiparticles in the excited state. When they decay into their initial state again, they release energy.Excitons may assume two different states: Singlet excitons decay immediately and emit light, whereas triplet excitons release their energy in the form of heat. Usually, 25 percent singlets and 75 percent triplets are encountered in OLEDs. To enhance energy efficiency of an OLED, also triplet excitons have to be used to generate light. In conventional light-emitting diodes heavy metals, such as iridium and platinum, are added for this purpose. But these materials are expensive, have a limited availability, and require complex OLED production methods.It is cheaper and environmentally more compatible to use copper complexes as emitter materials. Thermally activated delayed fluorescence (TADF) ensures high light yields and, hence, high efficiency: Triplet excitons are transformed into singlet excitons which then emit photons. TADF is based on the quantum mechanics phenomenon of intersystem crossing (ISC), a transition from one electronic excitation state to another one of changed multiplicity, i.e. from singlet to triplet or vice versa. In organic molecules, this process is determined by spin-orbit coupling. This is the interaction of the orbital angular momentum of an electron in an atom with the spin of the electron. In this way, all excitons, triplets and singlets, can be used for the generation of light. With TADF, copper luminescent material reaches an efficiency of 100 percent.Stefan Bräse and Larissa Bergmann of KIT's Institute of Organic Chemistry (IOC), in cooperation with researchers of the OLED technology company CYNORA and the University of St Andrews, United Kingdom, for the first time measured the speed of intersystem crossing in a highly luminescent, thermally activated delayed fluorescence copper(I) complex in the solid state. The results are reported in the Science Advances journal. The scientists determined a time constant of intersystem crossing from singlet to triplet of 27 picoseconds (27 trillionths of a second). The reverse process – reverse intersystem crossing – from triplet to singlet is slower and leads to a TADF lasting for an average of 11.5 microseconds. These measurements improve the understanding of mechanisms leading to TADF and facilitate the specific development of TADF materials for energy-efficient OLEDs.Reference:KY59-0202NYKY59-S101D2LCD-S301C31TR 

Using state-of-the-art theoretical methods, UCSB researchers have identified a specific type of defect in the atomic structure of a light-emitting diode (LED) that results in less efficient performance. The characterization of these point defects could result in the fabrication of even more efficient, longer lasting LED lighting."Techniques are available to assess whether such defects are present in the LED materials and they can be used to improve the quality of the material," said materials professor Chris Van de Walle, whose research group carried out the work.In the world of high-efficiency solid-state lighting, not all LEDs are alike. As the technology is utilized in a more diverse array of applications—including search and rescue, water purification and safety illumination, in addition to their many residential, industrial and decorative uses—reliability and efficiency are top priorities. Performance, in turn, is heavily reliant on the quality of the semiconductor material at the atomic level."In an LED, electrons are injected from one side, holes from the other," explained Van de Walle. As they travel across the crystal lattice of the semiconductor—in this case gallium-nitride-based material—the meeting of electrons and holes (the absence of electrons) is what is responsible for the light that is emitted by the diode: As electron meets hole, it transitions to a lower state of energy, releasing a photon along the way.Occasionally, however, the charge carriers meet and do not emit light, resulting in the so-called Shockley-Read-Hall (SRH) recombination. According to the researchers, the charge carriers are captured at defects in the lattice where they combine, but without emitting light.The defects identified involve complexes of gallium vacancies with oxygen and hydrogen. "These defects had been previously observed in nitride semiconductors, but until now, their detrimental effects were not understood," explained lead author Cyrus Dreyer, who performed many of the calculations on the paper."It was the combination of the intuition that we have developed over many years of studying point defects with these new theoretical capabilities that enabled this breakthrough," said Van de Walle, who credits co-author Audrius Alkauskas with the development of a theoretical formalism necessary to calculate the rate at which defects capture electrons and holes.The method lends itself to future work identifying other defects and mechanisms by which SRH recombination occurs, said Van de Walle."These gallium vacancy complexes are surely not the only defects that are detrimental," he said. "Now that we have the methodology in place, we are actively investigating other potential defects to assess their impact on nonradiative recombination."Reference:KY59-LM324MMKY59- LM2710KY59- LM3080 

For the first time, researchers have created light-emitting diodes (LEDs) on lightweight flexible metal foil.Engineers at The Ohio State University are developing the foil based LEDs for portable ultraviolet (UV) lights that soldiers and others can use to purify drinking water and sterilize medical equipment.In the journal Applied Physics Letters, the researchers describe how they designed the LEDs to shine in the high-energy "deep" end of the UV spectrum. The university will license the technology to industry for further development.Deep UV light is already used by the military, humanitarian organizations and industry for applications ranging from detection of biological agents to curing plastics, explained Roberto Myers, associate professor of materials science and engineering at Ohio State.The problem is that conventional deep-UV lamps are too heavy to easily carry around."Right now, if you want to make deep ultraviolet light, you've got to use mercury lamps," said Myers, who is also an associate professor of electrical and computer engineering. "Mercury is toxic and the lamps are bulky and electrically inefficient. LEDs, on the other hand, are really efficient, so if we could make UV LEDs that are safe and portable and cheap, we could make safe drinking water wherever we need it."He noted that other research groups have fabricated deep-UV LEDs at the laboratory scale, but only by using extremely pure, rigid single-crystal semiconductors as substrates—a strategy that imposes an enormous cost barrier for industry.Foil-based nanotechnology could enable large-scale production of a lighter, cheaper and more environmentally friendly deep-UV LED. But Myers and materials science doctoral student Brelon J. May hope that their technology will do something more: turn a niche research field known as nanophotonics into a viable industry."People always said that nanophotonics will never be commercially important, because you can't scale them up. Well, now we can. We can make a sheet of them if we want," Myers said. "That means we can consider nanophotonics for large-scale manufacturing."In part, this new development relies on a well-established semiconductor growth technique known as molecular beam epitaxy, in which vaporized elemental materials settle on a surface and self-organize into layers or nanostructures. The Ohio State researchers used this technique to grow a carpet of tightly packed aluminum gallium nitride wires on pieces of metal foil such as titanium and tantalum.The individual wires measure about 200 nanometers tall and about 20-50 nanometers in diameter—thousands of times narrower than a human hair and invisible to the naked eye.In laboratory tests, the nanowires grown on metal foils lit up nearly as brightly as those manufactured on the more expensive and less flexible single-crystal silicon.The researchers are working to make the nanowire LEDs even brighter, and will next try to grow the wires on foils made from more common metals, including steel and aluminum.Reference:KY59-LM324MMKY59- LM2710KY59- LM3080  

Application of LED lights is now common in various types of commercial settings. Irrespective of the type of business you own, you will find usage of commercial LED light within the premise. Reason for this is that such lights are of environment friendly type and give appealing look at different settings. Along with this, LED type of lights gives plenty of benefits and applications in different settings, about which experts have discussed here. In Various Mining EndeavorsToday, most of the mining industries are employing LED area light bulbs in wide range of settings because of their ability to provide outstanding strength, exceptional safety and longevity. Even people will find illuminating caverns comprise of LED lights used mainly in spotlights mounted on helmets and almost in every place, where they require usage of lights. Usage in Hospitality SectorHospitality industry is also a key area, where you will find LED lighting types of projects are making their headways. Majority of people have found significant decrease in the overall utility costs. Along with providing plenty of decorative lighting options to users and enhanced life spans, LED bulbs very hardly require replacements leading to reduction in maintenance costs. Application in City SettingsReplacement of only one traffic light with LED equivalent plays significant role to save the city's costing by about 93 percent of the energy consumed previously. Similarly, city authorities may replace lights displaying exit signs and down lights of vehicles with the help of LED down light options available in the market.  In fact, if you consider about commercial signage, you will find that it leads to about 2 percent of the total electrical consumption in different areas of United States every year. On the other side, by using of LEDs, one can expect to save money with a decrease of 80 percent in actual use. Savings obtained in terms of expenditure of energy for any small city may rise quickly to up to the range of six figures. Pay off associated with investments in cost saving yet affordable LED lights require only a period of about 2 to 3 years. Easy Replacement is PossibleBiggest benefit associated with LED bulbs is that design of those products fits perfectly in almost every possible type of light fixtures available in the market. Whether you own canned lighting type of business, traditional lamps or panels of fluorescent lights, you will expect to save many bucks by accommodating a single type of LED bulb. Reference:EB-251LRW5SM-GZHZ-1ABC02LSM670-H2K1-1