Bendable, stick-up display can go almost anywhere

Sept. 1, 1997
BALA CYNWOOD, Pa. - Industry and university scientists are working together to develop a paper-thin, bendable, full-color display that could enable systems designers of the future to affix data displays to virtually any transparent or opaque surface.

By John McHale

BALA CYNWOOD, Pa. - Industry and university scientists are working together to develop a paper-thin, bendable, full-color display that could enable systems designers of the future to affix data displays to virtually any transparent or opaque surface.

Display experts at Universal Display Corp. in Bala Cynwood, Pa., and Princeton University in Princeton, N.J., have developed such a roll-up display technology called "organic light emitting diode" that not only is conformable to almost any shape, but also offers a sharper image than today`s liquid crystal displays (LCDs), its proponents claim.

The transparent, flexible organic light-emitting device uses the basic building blocks of vacuum-deposited, organic small-molecule materials that emit bright light when stimulated electrically.

The thin, rugged, lightweight design has the potential to replace or augment a wide variety of existing displays, and to carve out many entirely new display applications.

For example, it could enable designers to remove the heavy cathode ray tube (CRT) from aircraft cockpit head-mounted displays, says Janice Mahon, vice president of technology commercialization at Universal Display. "The display can be put on the pilot`s visor."

Rapidly reconfigurable camouflage also is a possibility. For example, many camouflage schemes could be displayed on the bottoms of airplanes to enable their pilots to blend in with blue sky, darkness and stars, clouds, fog, or terrain.

Soldiers also may someday use this technology for attaching displays by Velcro to clothing, Mahon says. "They can take it off, type a message to their commander, and slap it back on a wristband."

Mahon cautions that while the technology has the potential for all these applications, it is still being optimized and is in the early stages of development.

The technology provides the opportunity for low-cost mass production using roll-to-roll processing, says Steven Abramson, president and chief operating officer of Universal Display. The monolithic device is built on a single surface, typically glass, and is about 1/1000 of the thickness of a human hair.

"These breakthroughs offer distinct advantages over existing technologies that include display transparency; the potential for cost-effective, high-resolution full-color; and the possibility of fabricating displays in various sizes on a variety of surfaces," he says.

"Our research partners have now shown the ability to combine two of their organic display inventions, transparency and flexibility, into a single device," Abramson says.

In its most common structures, known as a "single heterostructure," an organic device consists of a hole transporting layer and an electron transporting layer sandwiched between two conductive layers to form a solid-state thin-film device, Mahon says.

Typically, light emits from the bottom layer, which is transparent, while the top one, usually made of a material like aluminum, is opaque. This new technology uses a transparent top, thereby emitting light from both sides, Mahon says

The three enabling organic device technology platforms developed at Universal Display and at Princeton are transparent, vertically stacked, and flexible devices.

Transparent devices are possible in part because their organic materials are themselves transparent, which provides the foundation for a vertically stacked pixel architecture for high-resolution, full-color display applications.

Individual red, green, and blue transparent device elements are placed in a vertically stacked arrangement and individually contacted with a differential bias across each element, Mahon explains.

The traditional method has been to place red-green-blue organic device elements side-by-side in much the same way that CRTs and LCDs are configured for full color. It is like watching a big screen TV at a sports bar; when you are up close, the color is blurry and the human eye can see the individual red, green, and blue instead of the intended color mixture.

Yet with vertically stacked pixels, each pixel emits full color, no matter how large, Mahon says. It provides the potential for high-resolution images due to compact pixel size. This technology is equally applicable to head-mounted miniature displays, as it is wall-sized color TVs, she says.

Experts can fabricate these displays at low-cost due to the elimination of the side-by-side pixel growth, Mahon says.

The new displays can be made sunlight-readable by placing a black sheet behind the screen, Mahon says. The black sheet absorbs the sunlight, enabling only the light from the display to be visible. Otherwise the glare is the same as other displays, she says

Universal Display is also part of a team that won a $3 million contract from the U.S. Defense Advanced Research Projects Agency for the continued development of ultra light-weight, full-color organic diode flat panel display technology.

Princeton University is the research partner of Universal Display Corp., the exclusive licensee of this revolutionary organic display technology. For more information contact Universal Display`s Janice Mahon by phone at 609-258-6815, or by mail at P.O. Box 1157, Princeton, N.J., 08542-1157.

Click here to enlarge image

The transparent new screen from Universal Display promises to open a new set of display applications.

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