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Printed Electronics World
Posted on October 10, 2005 by  & 

Flexible OLED display progress

With liquid-crystal display (LCD) televisions only now making a significant impact in people's living rooms, it is hard to imagine that a new technology that might replace them is just around the corner.
The technology behind organic light-emitting diodes (OLEDs) is still in its infancy, but mostly monochromatic OLED displays can already be found in small gadgets such as mobile phones, personal digital assistants, MP3 players and car stereos. iSuppli Corp. forecast that the OLED industry will be worth US$650 million this year and rise to US$2.9 billion by 2011.
Inorganic LEDs are point sources of light whose emissive inorganic semiconductors are encased in little bulbs of glass. They are mostly used for lighting in electronic devices and as a graphics tool in signage and bulky outdoor displays, blinking on and off to create moving messages and low-definition images, as seen in sports stadiums, for example.
OLEDs, by contrast, are distributed light sources, consisting of extended polymeric membranes that glow. As such, they can be engineered to take the place of LCDs.
Whereas LCD panels require a color-filter layer, an inorganic LED backlighting module and a liquid-crystal layer to block or admit light from the module, in OLEDs these functions are all combined in the same layer of plastic, which glows locally with the desired color when electrically stimulated in the proper manner. Consequently, OLEDs are more energy-efficient and, potentially, a lot cheaper to make than LCDs.
An OLED comprises several layers: a substrate, an anode, two or more layers of polymeric material and a cathode. Electricity passing between the anode and cathode causes the sandwiched organic layer to emit light. Currently, the substrate backbone is normally made of relatively rigid glass. Research is being conducted on other substrate materials, however, that will make OLEDs more flexible as well as easier and cheaper to produce.
One of the trickiest parts of the OLED manufacturing process is applying the organic material to the substrate evenly. Research is progressing in using inkjet technology used in computer printers to spray the material onto the substrate with a high degree of uniformity. This technology similarly promises a significant reduction in production costs.
As in the LCD flat-panel industry, it is mostly East Asian manufacturers--particularly those in Japan, South Korea and Taiwan--that are shaping up as the most aggressive competitors in the battle for the fast-growing OLED market.
Though European and U.S. companies may not try to challenge East Asian companies for leadership in OLED manufacturing in their home countries, many of them in the electronics, chemical and lighting industries--including such heavyweights as Philips Electronics N.V., Eastman Kodak Co., Lucent Technology's Bell Labs and the DuPont Display Solutions affiliate of E.I. du Pont de Nemours and Co.--are pouring big bucks into OLED-related research in anticipation of rich patent royalties. They are also actively seeking out strategic partnerships with Asian companies.
Taiwanese companies are among the leading makers of small-sized OLEDs despite strong competition from Japanese and South Korean companies. According to market analyst DisplaySearch Inc., in the second quarter of the year, Samsung SDI Co. Ltd. of South Korea had regained the top position in terms of revenue after briefly being overtaken by Taiwan's RiTdisplay Corp. at the end of last year. Samsung had revenues of US$37.2 million in the second quarter, up 15 percent from the same period last year, compared with US$28.1 million for RiTdisplay, down 4 percent.
RiTdisplay was spun off in 2000 from Ritek Corp., the world's largest recordable compact disc maker. It started out using technology licensed from Eastman Kodak in June 2000 to produce full-color, high-resolution displays. In November 2000, Intel Corp. invested US$25 million in RiTdisplay, representing an 8.8 percent stake in the startup.
Other investors include General Electric Co. and DuPont Display Solutions, also known as DuPont Displays. The latter company cooperated with RiTdisplay in a 16-month-long R&D project that culminated in the opening of a new plant in 2002 that makes OLEDs exclusively for DuPont Displays.
Behind RiTdisplay in market performance are Japan's Pioneer Corp. and Taiwan's Univision Technology Inc., one of whose major shareholders is Wah Lee Industrial Corp. and whose OLED revenues jumped 157 percent from the same period last year, catapulting it ahead of South Korea's LG Electronics.
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