Georgia Institute of Technology uses Zinc Oxide nanowires to significantly improve LED performance

According to reports, the American physicist organizational network, Georgia Institute of Technology researchers use Zinc Oxide nanowires significantly enhance the GaN based light emitting diode (LED) transforms the current UV performance. The device is considered to be the first one to produce a charge in the piezoelectric material by piezoelectric electro optic effect, which can greatly enhance the performance of the LED. Related research reports published in the recently published "nano letters" magazine.

By applying mechanical strain on the nanowire, researchers at the Georgia Institute of Technology created the piezoelectric potential. The potential is used to adjust the charge transport and enhance the carrier injection of LED. The control of the piezoelectric potential to the photoelectric device is called piezoelectric photoelectric effect. This effect can increase the rate of electron and hole recombination to produce photons, and enhance the external efficiency of the device by enhancing the luminous intensity and increasing the injection current, so as to improve the efficiency of the device by 4 times.

The school of materials science and engineering professor Wang Zhonglin said that from a practical point of view, this new effect can have a lot of impact on the photoelectric process, including the promotion of lighting equipment, energy efficiency, etc.. Conventional LED generally uses quantum wells and other structures to trap electrons and holes, which requires a long time to stay close enough for recombination. The longer the electrons and holes are, the higher the efficiency of the LED device. Although the general internal quantum efficiency of LED can reach 80%, but the external efficiency of the traditional single p-n junction thin film LED is only 3%.

The Zinc Oxide nanowires in the new device make up the p-n junction of N, GaN film can be used as the P. The free carrier will be trapped in this interface. Piezoelectric photoelectric effect can be applied to the device under the condition of 0.093% compressive stress, so that the luminous intensity is increased by 17 times, so that the node current enhanced by a factor of 4, so that the photoelectric conversion rate increased by about 4.25 times. Under the influence of the appropriate external stress, the external efficiency of the new device can reach 7.82%, which greatly exceeds the external quantum efficiency of the traditional LED.

The team made LED can emit ultraviolet light of about 390 nm, but Professor Wang Zhonglin believes that the future can be extended to the visible range, applicable to all types of photovoltaic equipment. At present, efficient UV emitters are needed in the fields of chemistry, biology, aerospace, military and medical technology.

Professor Wang Zhonglin also said that the study opened up the use of piezoelectric - photoelectric effect to adjust the new field of optoelectronic devices. Greatly improve the efficiency of LED lighting is expected to bring considerable energy saving, it is very important for the application of technology in the field of green and renewable energy, in addition, this discovery can also be applied to other optical devices controlled by electric field.