2016 is about to end, reviewing the development of the LED industry throughout the year, and has achieved a gratifying breakthrough in many technical problems. According to online statistics, in 2016, the LED industry has obtained more than ten breakthrough LED related technologies.
US researchers can zoom in, or can the LED achieve zero light decay?
Researchers at the University of Illinois at Urbana-Champaign have developed a new way to increase the brightness and efficiency of green LEDs. Using industry-standard semiconductor crystal growth technology, researchers fabricated gallium nitride (GaN) crystals on silicon substrates that produce high-power green light for solid-state lighting.
"This is a breakthrough process," said Can Bayram, an assistant professor of electrical and computer engineering at the University of Illinois. "The researchers succeeded in producing new materials on a tunable CMOS silicon process, namely cubic GaN. ), this material is mainly used for green wavelength emitters."
Typically GaN forms one or two crystal structures, hexagonal or cubic. Hexagonal GaN is thermally stable and is a traditional semiconductor application. However, hexagonal GaN is more prone to polarization, and the internal electric field separates the negative electrons from the positrons, preventing them from being combined, thus causing a decrease in light output efficiency.
Bayram and Liu believe that their square GaN crystals could successfully achieve LEDs with zero droop. For green, blue or UV LEDs, the luminous efficiency of these LEDs will gradually decline with the input of current, which is called light decay.
The industry's first single crystal full color LED came out
Ostendo EpiLab., an Ostendo TechInc., Southern California, developed the world's first full-color LED. They used GaN materials to develop three special quantum structures that emit three different colors of light that can be emitted independently or in combination. Due to the power-saving and long-life characteristics of LEDs, full-LED displays made of full-color LEDs will likely replace the currently used liquid crystal technology (LCD) and even surpass organic light-emitting diodes (OLEDs).
New progress in the application of UV LED free-form surface light distribution technology
Under the support of Chongqing Science and Technology Plan Project, the Integrated Optoelectronic Technology Research Center of Chongqing Institute of Green and Intelligent Technology of Chinese Academy of Sciences has made important progress in the application research of UV LED free-form surface light distribution technology, and successfully used UV LED light source in the field of exposure machine. Has been applied in the PCB, LCD panel, touch screen and other industries. Related results have been granted national patent authorization (patent number: lens 201320875490.0 for UV LED collimation, high uniformity UV LED exposure head 201420651432.4).
The conventional parallel light exposure machine uses a high-pressure mercury lamp as a light source, and its life is only 1000 hours, which consumes high power and is polluted. The use of UVLED to replace the mercury lamp light source, the lifespan can reach 50 times of the mercury lamp, the power consumption can be reduced by 90%, the production cost of the enterprise is greatly reduced, and the environment is environmentally friendly.
At present, Chongqing Research Institute has broken through the key technologies of LED multi-free-form surface precise light distribution and inorganic optical component processing in the ultraviolet band. For the first time, a parallel light exposure head based on ultraviolet LED has been developed, and the parallel half angle can be controlled within ±2°. The illumination unevenness is less than 3%, and the illumination intensity is as high as 40 mW/cm2.
Saphlux develops new technology to overcome the unsolved problem of Nakamura Shuji
Saphlux, established in 2014, has repeatedly found a solution at the beginning of this year (involving the trade secrets and inconvenience to disclose it), breaking the original semi-polar gallium nitride material growth mode, not only in the standard The growth of semi-polar gallium nitride directly on a sapphire substrate can directly control the direction and shape of crystal growth.
The breakthrough of this underlying technology means that it is expected to break through the bottleneck of the quantum efficiency of the first generation materials and the green light gap, and make the next generation of high-power, high-efficiency LED and laser products, especially for medical and outdoor lighting. The field of high demand is of great significance.
Using new materials to make white LEDs
Recently, researchers at Tsinghua University in Taiwan published an article in "ACS Nano", which pointed out that researchers use materials other than rare earth elements to produce LED products that can emit white light. This LED is based on an alkali metal ruthenium, and a metal organic framework (MOF) is built. Graphene and other materials are combined on the upper and lower sides of the MOF to form an LED that can directly emit white light. The light emitted by the new material is very close to the natural light, and there is no strong blue light. Since there is no need to block other colors of light, the luminous efficiency is greatly improved.
Japan developed red LEDs that do not use rare elements
According to the Kyodo News Agency, the research team of Tokyo Institute of Technology and Kyoto University announced on the 21st that it has developed a red light-emitting semiconductor that does not use high-priced rare elements. It is reported that in the future, it is expected to use nitrides made of abundant nitrogen on the earth to be applied to red light-emitting diodes (LEDs) and solar cells at a low cost.
Research finds that hybrid nanocrystal LED design can reduce efficiency
Researchers at Nanjing University (NJU) used a hybrid nanocrystal to fill nanocrystals in a nanoporous indium gallium nitride (InGaN)/gallium nitride (GaN) blue LED structure. Greatly improve the efficiency of white LEDs.
In their study published in Applied Physics Letters, they pointed out that the key to improving color conversion efficiency (CCE) depends on efficient non-radiative resonant energy transfer, rather than combining blue InGaN/GaN LEDs with down. Radiation pumps that often occur when converting materials such as phosphorus or even semiconductor nanocrystals (NC).
Nangong University research team successfully developed the most efficient perovskite LED
It was learned from Nanjing University of Technology that the team of Professor Huang Wei and Professor Wang Jianpu of the Jiangsu Key Laboratory of Flexible Electronics made a major breakthrough in the research of perovskite light-emitting diodes (LEDs). They innovatively designed and prepared a multi-quantum well. The structure of perovskite LEDs has far more device efficiency and stability than other perovskite LEDs reported by international counterparts.
According to reports, this work has opened up new research directions for perovskite materials and their research in the field of luminescence, and it is expected that on the basis of further in-depth research, industrialization will be realized in the future.
WACKER launches new silicone rubber for LED packaging
Munich-based Wacker Chemie AG has successfully developed two new materials for LED packaging. These two silicone encapsulants, LUMISIL740 and LUMISIL770, cure into highly transparent silicone elastomers and withstand extremely high operating temperatures and intense light radiation without yellowing or embrittlement, especially for Efficient LEDs for packaging. The two new LED packaging materials, LUMISIL740 and LUMISIL770, are two-component formulations that can be crosslinked by a platinum-catalyzed addition reaction at room temperature. The vulcanizate can achieve a typical 1.41 refractive index of polydimethylsiloxane. The rate is "Normal RefracTIve Index Encapsulant". They can effectively protect LED-sensitive semiconductor chips from environmental influences, and can also be used as a carrier for fluorescent dyes to specifically change the color of LED light.
Taiwan researchers develop new materials to help improve LED life
At present, Taiwan researchers have developed a kind of aluminum heat sink that can really replace heavy and hard aluminum. The research team claims that the use of a heat sink made of polyamide (PA) and reduced graphene oxide (rGO) enables more efficient heat dissipation inside the LED lamp.
At the same time, the research team has developed a thermoplastic material that is comparable to the thermal properties of more expensive graphene and can be molded using an injection molding process that is easy to control. This material helps to produce low cost, light weight, flexible LED heat sinks and also increases the life of the LEDs.
LED heat sink technology has achieved new breakthroughs
Recently, Li Kuanan, a professor-level senior engineer of the China National Light Industry Association, introduced a self-innovative technological achievement with independent intellectual property rights, LED heat sink technology, to identify the key nodes of the current problems in lighting products, and successfully remove obstacles. The wire form and the fan forced way to dissipate heat, achieving a better heat dissipation effect. Zhang Yixing, the inventor and senior engineer of the project, said that it not only solves the problem of heat dissipation, but also makes an LED driver power supply that fully meets the requirements of “high efficiency, high reliability, low costâ€, and fundamentally solves the two factors that restrict the development of LED. a problem.
Professor Wenda invents materials to make white LED lamps last longer
Wenzhou University School of Chemistry and Materials Engineering, Lijiang Specially Appointed Professor Weidong, invented new materials, can extend the life of LED lamps for about 10 years, and can be used for a long time to make LED lamps more widely used in high-end cars, high-speed rail, aircraft. , submarine and other lighting.
Professor Wei Dong spent many years working on the yellow light single crystal material, which was produced in a high temperature environment of 2000 ° C, as long as one piece of each LED blue chip was matched (for example, 24 watts single). A single light source with a 5.5mm & TImes; 5.5mm single crystal matching yellow light single crystal material can emit stable white light. Due to the high temperature resistance and good thermal conductivity of the crystal, the LED lamp can be made more durable and has a longer service life, especially for the bulb not being damaged by the high temperature caused by long-time illumination, so it is very suitable for the lamp used in high-end cars. , high-speed rail, aircraft or submarine lighting.
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