A hybrid form of perovskite, the same type of material that has recently been found to make highly efficient solar cells that could one day replace silicon, has been used to make low-cost, easily manufactured LEDs.

Perovskite LED Samples.  Click image for the largest view.

Perovskite LED Samples. Click image for the largest view.

This particular class of semiconductor perovskites has generated excitement in the solar cell field over the past several years, after Professor Henry Snaith’s group at Oxford University found them to be remarkably efficient at converting light to electricity. In just two short years, perovskite-based solar cells have reached efficiencies of nearly 20%, a level which took conventional silicon-based solar cells 20 years to reach.

The new perovskite hybrid could lead to LED displays which are both cheaper and easier to manufacture in future.

Researchers from the University of Cambridge, University of Oxford and the Ludwig-Maximilians-Universit├Ąt in Munich have demonstrated a new application for the hybrid perovskite materials, using them to make high-brightness LEDs. The results have been published in the journal Nature Nanotechnology.

Perovskite is a general term used to describe a group of materials that have a distinctive crystal structure of cuboid and diamond shapes. They have long been of interest for their superconducting and ferroelectric properties. But in the past several years, their efficiency at converting light into electrical energy has opened up a wide range of potential applications.

The perovskites that were used to make the LEDs are known as organometal halide perovskites that contain a mixture of lead, carbon-based ions and halogen ions known as halides. These materials dissolve well in common solvents, and assemble to form perovskite crystals when dried, making them cheap and simple to make.

Zhi-Kuang Tan, a PhD student at the University of Cambridge’s Cavendish Laboratory and the paper’s lead author said, “These organometal halide perovskites are remarkable semiconductors. 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.”

Perovskite LED Buildup Diagram.  Click image for the largest view.

Perovskite LED Buildup Diagram. Click image for the largest view.

The perovskite LEDs are made using a simple and scalable process in which a perovskite solution is prepared and spin-coated onto the substrate. This process does not require high temperature heating steps or a high vacuum, thus they’re cheap to manufacture in a large scale. In contrast, conventional methods for manufacturing LEDs make the cost prohibitive for many large-area display applications.

Professor Sir Richard Friend of the Cavendish Laboratory, who led the program at Cambridge said, “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.”

Tan adds, “It’s remarkable that this material can be easily tuned to emit light in a variety of colors, which makes it extremely useful for color displays, lighting and optical communication applications. This technology could provide a lot of value to the ever growing flat-panel display industry.”

The team is now looking to increase the efficiency of the LEDs and to use them for diode lasers, which are used in a range of scientific, medical and industrial applications, such as materials processing and medical equipment. The first commercially-available LED based on perovskite could be available within five years.

This is a field where man’s ingenuity is racing along with both great energy saving and life enhancing results.


Comments

2 Comments so far

  1. STI Solaris on August 7, 2014 1:10 AM

    The advancements in solar energy are astounding to say the least. The more we can utilize growing technology the quicker the cost of solar will go down, and home installations will go up.

  2. Matt Musson on August 7, 2014 7:27 AM

    Cheap LEDs are exactly what we need!

    I am tired of those stupid curlycue mercury filled ‘faux’ green CFLs! The give out about as much light as a depressed firefly.

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