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17 Jun 2002
The market for organic light-emitting diodes is small. However, Phillip Hill discovers that the technology is fast becoming the star at trade shows and the darling of venture capitalists.
From Opto & Laser Europe January/February 2001
University and industry researchers, technologists, and, perhaps more importantly, market-research companies consider organic light-emitting diodes to be the most promising candidate to compete with liquid-crystal display technology.
Announcements on organic light-emitting diode (OLED) breakthroughs from businesses and university departments abound. The current market may be tiny, but it is growing exponentially.
Owing to their potentially cheap fabrication, low power consumption compared with other
technologies, and high brightness and contrast, OLEDs are believed to be capable of superseding the
established liquid-crystal display technology in the most important market areas.
"The market will explode between 2006 and 2010," said David Mentley, vice-president of Stanford
Resources.
Mentley believes that OLEDs are the best devices to use to build displays owing to their solid-state
structure, their many manufacturing options and because they can generate and modulate light when and
where it is needed. "This is the first time that this has been possible in a low-voltage, full-colour system," he
emphasized.
Aris Silzars, president of the Society for Information Displays, is also optimistic about the future of
OLEDs. "If I had to pick one technology right now it would be OLEDs," he said. "There will be rapid
development over the next 10 years."
A sign of the times was an announcement last month from Cambridge Display Technology (CDT), a
principal pioneer of OLED technology. It has licensing agreements covering its light-emitting polymer
(LEP) materials technology with a host of major display manufacturers worldwide. However, the company
is now confident enough to put USD 25 million into a manufacturing facility of its own in the UK.
"This investment is a major step for CDT," said CEO David Fyfe. "We have spent the last five years
developing the technology base to enable the commercialization of LEP displays. Several of our licensees
have announced that they will launch commercial products in 2001 and this investment will enable us to stay
at the forefront of OLED technology development."
CDT is just one of many businesses that are injecting money into OLED development. Stanford
Resources estimates that there are more than 80 company projects at the moment, with as many as 50
government and university laboratories taking part in the research effort.
Many OLED material systems exist that are perfect for theoretical research in universities and
corporate laboratories. As a result, the path to a practical display demonstration is a short one compared
with other types of flat-panel display (FPD).
"The manufacturing options abound," said Mentley. "Precursors can be spun, sprayed, printed,
extruded and stamped."
He believes that the first target markets for OLEDs are LEDs and vacuum fluorescent displays
(VFDs). However, the greatest potential lies in the LCD market. Mentley insists that the LCD sector is
complex and the part that OLEDs could address is only one-third of the LCD market.
Future growth will be cost/price driven and Stanford Resources says that OLEDs will eventually
have a cost advantage in both active and passive formats.
Four principal groups are conducting research into OLEDs. First, large companies that are devoting
considerable resources, including Eastman Kodak, Du Pont, Dow Chemical and Seiko Epson. Second, large
firms that are keeping abreast of developments but are not racing to commercialize the technology, such as
Agilent and IBM.
Third, start-ups that are extensions of university research and that are focused exclusively on the
field. They include Uniax, CDT, FED Corporation and Universal Display Corporation (UDC).
Finally, university research groups, the most important of which are the University of Cambridge in
the UK, Eindhoven University of Technology in the Netherlands, and the universities of Southern
California, Princeton, Pennsylvania and MIT in the US.
OLEDs fall into two competing technologies: large molecules (polymers) and small molecules
(crystalline materials). The main advocate of the small-molecule approach is Eastman Kodak, while the
pioneer in the polymer field is CDT.
CDT has partnerships with Covion, Du Pont, Agilent, Hoechst, Philips, Seiko Epson and Uniax.
Most of these collaborations involve licensing that has effectively removed the possibility of serious
challenges to CDT's fundamental patents.
Kodak has an equally impressive patent portfolio in small-molecule OLEDs and the company has
also gone down the road of licensing agreements. The most significant is probably the development
agreement with Sanyo Electric. The two companies created a stir at the SID exhibition in Long Beach last
year when they showed a 5.5-inch video display with the promise of larger ones coming out later this year.
Mike Weaver of UDC says that in the next few months we will see published papers from his
company announcing 100% efficiencies for flexible displays and lifetimes of more than 10,000 h with new
structures.
Lifetimes are a problem, he admits, because water goes straight through the polymers that are used in
the flexible structures. UDC is working on multilayer barrier coatings that consist of layers of polymer and
high-density dielectric films. A lifetime of more than 1000 h has been achieved so far. "Six months ago the
figure was approximately 100 h," said Weaver.
The ability to place OLEDs on a flexible substrate provides the rugged, durable performance that is
required in hand-held electronic devices, such as mobile phones.
Flexible OLEDs lend themselves to high-volume, roll-to-roll process manufacturing, promising
relatively cheap fabrication.
"OLEDs are beginning to enter the market-place as a competitive technology," said Weaver. "This
type of display should move rapidly from small passive matrices to full-colour active matrices - which are
built on conventional indium tin oxide coated glass - and then on to plastic substrates."
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