According to United States physicist organizations network on October 31, the United States Georgia Tech researchers use zinc oxide Nanowires have dramatically boosted gallium nitride light-emitting diode (LED) convert current into the efficacy of ultraviolet rays. This device is considered to be the first through piezoelectricity, electro-optical effects in piezoelectric materials become electrically charged, so that the performance boost of their own LED. related study, published in a recent issue of the journal Nano letters.
By mechanical strain imposed on nanowires, researchers at Georgia Tech in which manufacturing of piezo-electric potential. The potential is used to adjust the charge transport, and strengthening LED carrier injection. This piezoelectric control of potential for opto-electronic devices is called piezoelectric-the photoelectric effect. This effect can increase the rate of electron and hole reunite to produce photons and by upgrading the luminous intensity and increase injection current, strengthening the external efficiency of the device, making it up to 4 times in a row.
Director of the school of materials science and Engineering Department Professor Wang Zhonglin said, from a realistic point of view, this new effect can have many effects on electro-optical processes, including improving the energy efficiency of lighting installations, and so on. Traditional LED general use quantum well structure of trapped electrons and holes, which requires both maintain close enough for a long time to restructure. Electrons and holes near the longer, the higher efficiency of LED devices. While the General LED internal quantum efficiency can reach 80%, traditional single p-n junction points outside of the film LED efficiency was only 3%.
Zinc oxide Nanowires constitutes a new installation of p-n junction n, gallium nitride thin films can be used as one of p. Free carriers are trapped in the interface area. Piezoelectric-the photoelectric effect can be compressive stress imposed on the device 0.093% case, luminous intensity up to 17 times, and knot current enhanced 4 times, so that the photoelectric conversion rate increased by about 4.25 times. At the right under the effect of external stress, newly installed external efficiency can reach 7.82%, considerably more than the traditional external quantum efficiency of the LED.
Made of LED the research team can make approximately 390 nm wavelengths of ultraviolet, but Wang Zhonglin Professor the next extends to the visible light range, applicable to all types of opto-electronic devices. At present, efficient UV emitters in the chemical, biomedical, aerospace, military and medical technology are necessary.
Professor Wang Zhonglin also said that this research has opened up use of piezoelectric-the photoelectric effect adjusting the new field of opto-electronic devices. Significantly enhance the efficiency of LED lighting equipment is expected to bring in substantial energy savings, which is in green and renewable energy technology applications in the field are important, in addition, this finding also applied to other controlled by electric field on optical devices.
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