January 1999

Displaying a Winning Glow

Continued from page 1

By Michael Kenward

Plastic TVs

Early last year, the company grabbed headlines around the world when it unveiled a working TV screen that measured only 50 millimeters square and only 2 millimeters thick. The device is just a crude prototype but is meant to demonstrate a replacement for the bulky bottles behind most TVs. It was jointly developed with the Japanese electronics giant Seiko-Epson, and the companies billed it as the world's first plastic television screen. It used a simple monochromatic display and showed the British cartoon characters Wallace and Gromit in a sickly shade of green. But CDT and Seiko-Epson promise soon to show off the first full-size color display using light-emitting polymers.

The glowing polymers are gunning to become a factor in the worldwide race to commercialize technologies for flat-panel displays-thin screens that, in one projected use, could be used in a TV that hangs on the wall. For all their success in making flat screens for portable computers, technologies such as liquid-crystal and plasma displays have yet to displace the clunky cathode ray tube from the desktops of the world, let alone the living rooms. Meanwhile, newer technologies, such as field-emission devices-which essentially rely on miniaturized versions of the electron guns used in cathode ray tubes-have proven expensive to make. That leaves a big opening for the light-emitting plastics. If they can be made to work.

A commercial TV with a plastic screen is still several years down the road. In the short term, CDT and its partners plan to market LEPs for the displays in mobile telephones or the simple indicators used in such products as appliances and CD players. That's now largely the domain of liquid-crystal displays and LEDs, and it's a roughly $2.5-billion-a-year business. As TR went to press, Philips Electronics, which licensed the rights to CDT's technology in 1996, was scheduled to begin test-manufacturing LEPs for these uses.

The potential has made light-emitting plastics one of the hottest areas of materials research, drawing the attention of electronics and polymer makers around the world. While it's doubtful that any one company will dominate the business, CDT has used its strong patent position and a clever business strategy to ensure its technology plays a key role. Even more remarkable, the 33-employee startup has outcompeted some of the world's largest materials science research groups in doing so.

Light-emitting plastics are so appealing in electronic applications because they can be used to make LEDs whose active ingredient is a tiny diode made of a polymer rather than crystals of gallium arsenide or the other inorganic materials used in conventional LEDs. Polymers can be chemically tailored to produce light of any wavelength that you care to mention; in contrast, it can be difficult to adjust the colors emitted from inorganic semiconductor crystals and some hues are particularly elusive. Polymers are also far easier to manufacture and process than the inorganic semiconductors used in current LED displays.

A further attraction of LEPs is that, unlike the liquid-crystal displays used in many laptop computers, you can view them from any angle-as anyone who has used a laptop knows, you have to stare it straight in the face to see its contents properly. What's more, LEPs avoid the streaking, or ghosting, of images that plagues flat-panel displays using liquid crystals, because the tiny plastic light emitters can switch on and off extremely rapidly. In contrast, liquid crystals often do not respond quickly enough to keep up with the image as it flashes across the screen.

But the streaking isn't the most serious obstacle posed by the current technologies. Liquid-crystal displays must be sandwiched between two layers of glass; and, since they don't create light themselves, there must be a light-emitting layer behind them. What has really captured the imagination of electronics producers is that LEPs can be put down as thin films on various substrates, including other plastics. That means you could coat a cheap, flexible sheet of plastic with a thin layer of LEPs. The potential products are almost endless: from a glowing Barbie doll to screens that can be rolled up and stored to permanent, rapidly changing signs that could be put up like wallpaper.

That's the promise. The reality is that commercializing new electronic materials is a fickle and expensive process. It takes time-and manufacturing clout. It is for precisely these reasons that CDT has hedged its bets by forming alliances with several leading manufacturers. Leveraging the strength of its fundamental science and patent portfolio, CDT has wooed many of the industry's largest corporate players, becoming a technology partner with the likes of Philips Electronics, Seiko-Epson, DuPont and the giant German plastics maker Hoechst.

Polymer PartnersCompanyTermsObjectiveDuPont
(March 1998)Two-year joint development agreement.Supply LEPs to electronic makers.Seiko-Epson
(Feb. 1998) Joint development agreement to combine LEPs with active matrix display technology.Market full-size color displays for computers and TVs.Hoechst
(May 1997)Hoechst pays up-front fee for access to CDT's patents.Hoechst to provide LEPs to electronic customers.Philips Electronics
(Sept. 1996)Philips pays license fee and royalty on any LEP products.Philips to initally market backlights for LCDs and displays for consumer products.