But the University of Utah physicists say the effort to build a plastic semiconductor switch for future ultrafast computers and electronics may be more difficult than thought, due to the problem of making highly efficient light-emitting diodes using organic materials.

The scientists, led by Assistant Professor Christoph Boehme and Associate Professor John Lupton, said their findings suggest such LEDs would convert no more than 25 percent of electricity into light rather than heat, contrary to earlier estimates of up to 63 percent.

Organic semiconductors, or "plastic" LEDs, are much cheaper and easier to fabricate than existing inorganic LEDs, now used in traffic signals and as indicator lights on computers, TVs, cell phones, and other electronics.

"This is the first time anyone has done really fundamental, hands-on quantum mechanics with an organic LED," Lupton says. "This is tough stuff."

The study that included postdoctoral researcher Dane McCamey and doctoral students Heather Seipel, Seo-Young Paik, Manfred Walter and Nick Borys is detailed online in the journal Nature Materials.