Flexible, Stretchable LEDs Promise Better Displays

Aug. 21, 2009 -- Bend it, twist it, roll it or stretch it, a new light emitting diode, or LED, created by scientists will still light up.

The new flexible and stretchable LEDs could be used in everything from bumper mounted brake lights to computer and television screens that roll up into a pen.

"These new inorganic LEDs are so thin you can roll them up, bend them over, and it doesn't affect their operation at all," said John Rogers, a scientist at University of Illinois at Urbana-Champaign and co-author of the paper that appears in this week's issue of the journal Science.

The two varieties of LEDs, organic and inorganic, appear on on everything from billboards to cell phones.

Organic or carbon-based LEDs are generally smaller and easier to manufacture, which is why they appear on cell phone screens. In general, inorganic LEDs are more difficult to create, needing higher temperatures and harder surfaces.

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Inorganic LEDs, however, tend to have higher performance than their organic counterparts. Inorganic LEDs are generally brighter and more efficient, which is why they are typically used in traffic lights, flashlights and outdoor electronic billboards.

"Think about a big billboard display made of (inorganic) LEDs," said Rodgers. "You can see the image clearly on a sunny day, but if you get close, you realize the individual LEDs are large and rather clunky."

The new inorganic LEDs don't have that issue. In fact, at 20 microns across and two microns tall, they are smaller than a 50 micron diameter human hair. Using commercially available printing technology, scientists say the LEDs could shrink to five microns across.

That tiny size gives the LEDs a flexibility and stretchability that no inorganic LED has ever achieved.