Researchers develop new light emission technique

Who knew that jellyfish and other bioluminescent creatures could contribute to the future of flat-screen technology? Electrical engineering professor Stephen Forrest and Marc Baldo GS have discovered just that.

Starting two years ago, these researchers combined commonplace fluorescent material with phosphorescent molecules harvested from luminescent animals, and found it was possible to emit the same amount of light with less energy input, paving the way for various high-tech developments.

"The fundamental difference between the two materials is that phosphorescence takes a long time to give out light, while florescence gives out less light, but more quickly," Baldo said. "We tried to get the best of both systems and produce more efficient light."

Prior to this discovery — which was published in the Feb. 17 issue of "Nature" — phosphorescence and fluorescence were used separately.

Equipment that uses phosphorescent light-producing material in addition to fluorescent material is more efficient, and thus lengthens the life span of batteries in portable electronic devices.

"It would mean that all your hand-held electronic devices, such as a palm pilot or a lap top, would be very efficient because of the extended battery life," Forrest said.

Forrest said the increased efficiency could save consumers money. "Instead of a battery that lasts 2.5 hours, it would now last five hours, which is a good deal," he said.

Forrest and Baldo — who collaborated with University of Southern California chemist Mark Thompson — used their discovery to increase the efficiency of an organic light-emitting diode, a device that will accelerate the development of flat-panel television and computer screens.

Previously made of either fluorescent or phosphorescent material, OLEDs are thin films of molecules that are excited by electrical currents to emit light. The application of the phosphorescence-fluorescence combination quadrupled the efficiency of the diodes.

OLEDs differ from liquid crystal displays, which are used in computer and television screens. OLEDs provide a brighter image with truer colors and a smaller pixel size.

OLED technology has exciting possibilities because it can be applied to an area of any size, Baldo said. "My ultimate objective is to make televisions the size of buildings," he said.

Not only can an OLED make such a feat possible, but they can also be used to make luminescent walls and floors, according to Baldo. "So instead of having 10 different light bulbs, you can just flip up a switch and just light up your walls and floor," he said.

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Panasonic already has made the first product with this technology, a car radio display used in Japan. The technology will be ready to be applied to other products within six months, according to Forrest.