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Organic LEDs to light up electronics

David Hadcock, a senior electrical engineer at Kodak, holds the company's OLED display technology at its headquarters in Rochester, New York, last week. PHOTO: AP

A new technology that makes cellphone screens glow like a firefly's tail may well be destined to brighten displays on everything from televisions to digital cameras.

Built on organic molecules or polymers that glow when they're electrified, the technology could even spur the currently unattainable: roll-up computer screens that can fit in a breast pocket or sheets of radiant lighting that shimmer like the aurora borealis.

"Imagine a plastic film or a fiber-optic cable that emits light, that you can bend in any shape you want," said Stewart Hough, vice president at Cambridge Display Technologies, "It's one of those limited-by-your-imagination things."

Hough's company is developing a polymer-based version of the technology, known as organic light-emitting diodes or OLEDs (A diode is a piece of electronics in which current flows in only one direction).

Chemical, electronics and lighting companies -- including Kodak, Samsung, Philips, DuPont and others -- are pouring funds into research and development of OLEDs, rushing tiny screens to market and scrambling to race ahead of competitors.

For now, the monochrome screens appear on a handful of products: cell phones, an MP3 player, car stereos. As the bright new screens mature into full-color displays with an active matrix that permits video, analysts say they'll jump to digital camera displays, auto dashboards, laptop screens and TVs.

Global sales of OLEDs, estimated at just US$80 million this year, are expected to jump to US$2.3 billion by 2008, said Kimberly Allen, research director at iSuppli/Stanford Resources, a firm that tracks the industry.

As OLEDs progress, analysts say they'll replace the silicon-based LCD, or liquid crystal display technology, that's used in everything from watches and calculators to flat-screen monitors and some TVs.

OLED screens are made up of of arrays of tiny diodes made of organic materials used in plastics and polymers. The diodes in today's little screens are sandwiched between layers of glass, glowing in various colors as electricity flows through them.

The delicate organics wither and die at a hint of moisture, so glass is needed to keep them dry.

Experts say it will be a decade or so before someone figures out how to make a durable OLED screen on a plastic base, perhaps a flexible one, which would require flexible circuit boards and other components.

A few companies, including DuPont and Lucent Technologies' Bell Labs, are already working on bendable plastic electronics for such a screen.

"You could put it on curved surfaces," said Alan Heeger, professor of physics at University of California at Santa Barbara. "You can imagine nifty-looking things."

Heeger, whose discoveries in polymer conductivity earned him and two colleagues a Nobel prize in 2000, said the innovations in lighting could be more dramatic than those in consumer electronics.

OLEDs, coupled with mature inorganic LED technology that already brightens traffic signals and auto taillights, could replace incandescent and fluorescent light bulbs with wallpaper that changes lighting patterns and colors, sheets of radiant film that could be cut to size or light cords that accent walls, handrails or steps, Heeger said.

Today's OLED-bearing products are comparatively mundane.

The first emerged in a Pioneer car stereo in 1998. Since then, they've shown up in cell phones made by Motorola, Fujitsu and LG, an MP3 player made by Taiwanese firm Delta Optoelectronics and a Philips men's shaver sold under the Norelco brand in the US.

The shaver, with its orange screen that displays battery life, turned up in the recent James Bond movie Die Another Day.

For next year, Samsung is making a cell phone with the first full-color OLED display, for sale in South Korea, Allen said.

And Kodak is quietly shipping 5cm horizontal OLED screens to a consumer device manufacturer it refused to name.

Those screens, configured in the manner of those used in digital cameras, are the first to use active-matrix technology that can play video, said Daniel Gisser of Kodak's display products unit. The product will emerge in the first half of next year, Gisser said.

Larger screens for handheld computers and video cameras might be ready in a year or two, said Paul O'Donovan, an analyst with Gartner Dataquest.

Prototypes of 38cm and 43cm screens have been cooked up, although none are expected to hit stores for years. O'Donovan said OLED PC monitors might be available in four to five years, televisions in five to 10.

"The trouble is scaling them up," O'Donovan said. "They've got a 6.3cm screen working impressively. The real technological leap will be to expand these into the replacement of TVs."
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