April 2001

A Bright Future for Displays

Continued from page 3

By Bob Johnstone

Into the Red/Green/Blue Yonder

All this activity represents the first wave of what many insiders believe will be a revolution in displays for devices ranging from small-screen applications such as digital camera viewfinders to handheld computers and laptops. Here, the stakes are far bigger than with cell phones, which DisplaySearch estimates will represent only about a tenth of the total $75 billion liquid crystal display market in 2005.

Last December, eMagin, a startup in Hopewell Junction, NY, made a first strike on this vast market by garnering the Society for Information Display's Display of the Year Gold Award for its advances in organic light-emitting diode technology, including a prototype 1.5-centimeter active matrix display it hopes will set a new standard for viewfinders. Then there's the hit of the prototypes, the Kodak-Sanyo 14-centimeter active matrix panel exhibited in Long Beach as the future of handheld devices like the Palm Pilot. "It's an absolutely fantastic-looking display," enthuses Nick Colaneri, director of new technology at Uniax, DuPont's just-acquired organic light-emitting diode subsidiary, which has its own offering in the works. "Paper thin, really beautiful. They put it next to an active matrix LCD, and it just blew the LCD away."

Indeed, if the industry buzz is to be believed, organic light-emitting diodes hold the potential to blow away the entire economics of display making. One approach is to dramatically lower manufacturing costs by printing displays directly from an inkjet printer onto a substrate. Last July, Seiko Epson demonstrated a full-color 6.3-centimeter screen made using this method. A next step might be to replace glass with plastic as the screen's substrate. That will produce a display cheaper, lighter and more rugged than today's organic offerings. But the critical point is that once the substrate is plastic, it is easy to imagine a transition from the current, hands-on batch production to an automated rolling process where displays are churned out more like newspapers than chips.

Beyond new forms of manufacturing comes a potentially even bigger step, in which polymers replace silicon in the thin-film transistors that form the active matrix backbone. Philips Electronics, Lucent Technologies, and Plastic Logic, formed last year by Richard Friend, are among those exhibiting prototype polymer transistors. Combined with a plastic substrate, this advance could enable a further milestone: electronic paper (see "Electronic Paper Turns the Page," TR March 2001).

Of course, talk about e-paper and other advanced applications is getting ahead of the story, since organic light-emitting diodes face obstacles in nearly every application. One serious current problem is color. Leave the Kodak screens on for a month or so, and the color becomes very nonuniform. Reds and blues die first, leaving a very green display. Cambridge Display Technology has done better with its polymer displays, achieving a working life of 100,000 hours for red and 30,000 hours for green-but just 1,000 hours for blue.

Both technologies are probably good enough for cell phones, which are typically used 200 hours a year and would likely be replaced before the colors start to fade. But such performance is not adequate for handheld or laptop displays, for which several thousand hours of life are required. "Whether the material technology can make it to that level has yet to be proven," admits Kodak's Tang. And the list of technical obstacles grows longer the farther out one looks.

Ultimately, however, the biggest challenge that organic light-emitting diodes face may not be so much technological as commercial. That is, while liquid crystal displays will probably fail to match the attractiveness or performance of organic light-emitting diodes, they will continue to be reliable and affordable-and their manufacturers will no doubt find ingenious ways of further lowering costs and improving capabilities. As analyst Mentley warns, "I haven't heard of any of these LCD guys saying they're just going to fold up and go away. It's going to be a battle."

Still, the battle is joined. And, as Richard Friend notes, few technologies last forever. "I mean, really new things will happen," he asserts. It looks as though organic displays could be one of those really startling new things that come barreling over the technology horizon.