August 5, 2014…Perovskite, a material that was recently found to produce efficient solar cells, has been used to fabricate low cost LEDs. The LEDs reportedly have potential for commercial applications including flexible color displays. Researchers from the University of Oxford, University of Cambridge, and the Ludwig-Maximilians-Universität in Munich have used Perovskite materials to make high-brightness LEDs. The results are published in the journal Nature Nanotechnology and explained in a Cambridge University press release.
Professor Henry Snaith’s team from Oxford University found that they are extremely efficient at converting light to electricity. In just two years, perovskite-based solar cells have reached efficiencies of nearly 20%, a level which took conventional silicon-based solar cells 20 years to reach. Perovskite is a general term used to describe a group of materials that have a distinctive crystal structure of cuboid and diamond shapes. The researchers used organmetal halide perovskites that contain a mixture of lead, carbon-based ions and halogen ions known as halides. The simple to make materials dissolve well in common solvents, and assemble to form perovskite crystals when dried.
“These organometal halide perovskites are remarkable semiconductors,” said Zhi-Kuang Tan, a PhD student at the University of Cambridge’s Cavendish Laboratory and the paper’s primary author. “We have designed the diode structure to confine electrical charges into a very thin layer of the perovskite, which sets up conditions for the electron-hole capture process to produce light emission.”
According to the researchers, the perovskite LEDs are made using a simple of spin coating a perovskite solution onto the substrate. Unlike methods for fabricating conventional LEDs, the process does not require high temperature heating or a high vacuum to manufacture.
“The big surprise to the semiconductor community is to find that such simple process methods still produce very clean semiconductor properties, without the need for the complex purification procedures required for traditional semiconductors such as silicon,” said Professor Sir Richard Friend of the Cavendish Laboratory, who has led this program in Cambridge.
“It’s remarkable that this material can be easily tuned to emit light in a variety of colours, which makes it extremely useful for color displays, lighting and optical communication applications,”said Tan. “This technology could provide a lot of value to the ever growing flat-panel display industry.”
The team is now hope to increase the efficiency of the LEDs and to use them for diode lasers, which are used in scientific, medical and industrial applications, such as materials processing and medical equipment. The researchers estimate that the first commercially-available LED based on perovskite could be available within as little as five years.