As a growing number of flat panels based on new materials reach the production stage, system designers will be able to expand into many more market segments. They will have the option of building compact units integrated into such everyday products as appliances and automobiles.

"Beyond cell phones, PDAs and handheld computers, one industry that is anticipating new developments with much excitement is the automotive industry," said Janice Mahon, vice president of technology commercialization at Universal Display Corp. (Ewing, N.J.). "OLEDs [organic light-emitting diodes] represent a new platform for integrating more display capability within the car," she said, referring to the company's ongoing work in OLED structures for novel applications.

Universal Display is a company born from the push to commercialize research on highly efficient OLED materials at Princeton University. The company has continued that work in a number of directions. One fallout is the ability to print bright color displays onto transparent, flexible substrates. "The concept of flexibility allows the display to more easily conform to the interior of the car, and the fact that plastic is significantly safer than glass enables designers to work in areas of the car where current laws do not allow them," Mahon said.

Transparent OLED displays could also be sandwiched into the front windshield, invisible to the driver unless turned on. They could be used to flash warning information picked up by sensors such as night vision infrared images. Cadillac currently has a night vision system based on a projection display that puts imagery on the windshield. Today Mahon sees an inherent paradox in the information appliance industry: "While products are getting smaller, the need for information keeps growing, so it is hard to keep shrinking displays," she said.

One area companies are researching is the development of OLEDs on flexible plastic substrates. A key advantage over existing flat-panel displays is the ability to roll such displays up. "While there are a number of challenges that need to be overcome before commercialization, the potential," Mahon said, "is to produce displays and light-generating devices in a web-based process roll-to-roll format, at miles a minute, instead of pennies a day, that will significantly impact the display and lighting industries." One innovative design the company is working on is a new kind of communications device-essentially, a pen with a pull-out flexible display.

There is a tremendous market for handheld devices for both passive-matrix and active-matrix OLED displays. The distinction between the use of active and passive matrices typically relates to power budget. "An OLED on an active-matrix backplane consumes about one-half the power of a passive-matrix version," Mahon explained. "Otherwise, unless one gets into thinking about the direct integration of driver chips onto the backplane vs. the use of discrete chips, both approaches will perform at video rate, will operate in full color and are fairly similar."

OLEDs are deposited in a vacuum chamber and are therefore difficult to scale up to monitor size with current technology. Currently, Universal Display is working with Sony Corp. and Samsung SDI Co. Ltd., both of which have demonstrated fairly large-area active-matrix OLED prototypes.

Last May, Sony demonstrated a 13-inch full-color active-matrix OLED and Samsung came out with a model 15 inches on the diagonal. Despite this, Mahon believes that the commercialization road map will start small and gradually grow in size as the industry comes up the learning/yield curve, particularly in manufacturing.

Mahon sees many companies moving out of an R&D mentality and aggressively committing resources to a manufacturing infrastructure, but it takes longer for companies to get enough experience in yield to bring costs down. "That's the remaining challenge for cost-effective, first-generation products," she said. "Materials are getting to the point where they are meeting first-generation product requirements. Now the challenge is to produce enough of them to get the cost down." OLED displays are fairly expensive today, but intrinsically OLEDs will cost 50 percent to 70 percent of what a comparable LCD would cost today. First, though, yields have to go up.

One company, eMagin Corp. (Hopewell Junction, N.Y.), is developing active-matrix OLED displays on 8-inch silicon wafers. The display circuitry is first manufactured on the chip at a foundry; then eMagin deposits the final optically active OLED layers-four layers about 150 nanometers thick.

The company just got a million-dollar grant from the Air Force to merge the OLED display image with the image from night vision tubes. "Pilots have night vision systems that amplify light from outside and they want to superimpose generated images with information as an overlay on that image," explained Webster Howard, chief technology officer at eMagin.

Universal Display Corp. is able to house organic LEDs (OLEDs) as a flexible display inside a pen that opens (l-r) a window onto the Internet in a small form factor.

The Air Force is also interested in daytime applications, essentially a very bright microdisplay that superimposes an image that bounces off the visor of the pilot's helmet. By looking at the image transmitted to the visor, the pilot can view what's ahead in the sky. "The idea is to have the image bright enough so that even if the pilot is looking at bright clouds, the superimposed information shows what might be behind them," Howard said.

Larger commercial applications will be in "3-D reality," where this capability could introduce a new phase for computer games. "You could put on a goggle projecting 3-D images of a synthetic world," Howard said, "and a head-tracking system would allow you to look around this synthetic world as though it were external reality." The technology could also enable wearable computers in the medical and inspection industries.

Other military applications: a helmet or backpack with a swing-down display that provides the soldier with a map of the terrain, navigation information and real-time data on enemy positions. "The Army tested this concept with parachuting operations at night in unknown territory," said Howard. Studies showed that reassembling and organizing troops averaged six hours. When the troops used a display connected to a global-positioning satellite system, that time was cut to less than an hour. "You hit the ground and look at the display, which tells you where you are and shows you where you need to be," he said.

Howard believes that so far, polymer LEDs have not been able to match the small-molecule materials, especially in the blue region, needed to make full-color displays. "We see Philips and Dupont in the market first with yellow or green monochrome displays, but more work needs to be done to get a decent blue, which is essential for white or full color," he said.

One of the more innovative display developments is electronic ink. Devised at E-Ink Inc. (Cambridge, Mass.), the concept is based on a printable ink that operates reflectively just like conventional ink but can be electronically altered. The ink is made up of microcapsules that are on the order of 40 to 70 microns in diameter. Submicron black and white oppositely charged particles are inside each microcapsule. An electrical field lies across two transparent electrodes, one on the top and one on the bottom, causing the white pigment to migrate to the surface of the microcapsule and the black to the back. The result is a black or white printed area. The process can be stopped midway to create stable gray-scale images. When the power is turned off the image remains as it was configured.

The product has a paperlike look with reflectivities in excess of 40 percent. "That's 40 percent with no power applied to it as you view it. Contrast ratios are greater than 10:1 and, just like paper, you can look at it from any angle," said Mike McCreary, vice president, research and development, at E-Ink.

Flexibility and bendability are key design advantages. "Unlike LCDs that need a very accurate cell gap, flexible displays made from electronic ink can bend and can also be read in bright light, unlike OLEDs," McCreary said. "And they can also be read in subdued light indoors without having a backlight or front light, unlike reflective LCDs."

The company plans to roll out its first handheld electronic displays next year in collaboration with Philips. Specific products will include electronic books, cell phones and personal digital assistants. E-Ink will ship the sheets of electronic ink, and Philips will laminate them onto its displays. The company plans to start with reader-related, black-and-white applications.

On the mainstream LCD front, computer monitors and flat-panel televisions are currently proving to be the high-growth areas. Experts forecast that revenue from the passive-matrix market will be flat for the next few years.