Semiconductive ink and new materials may make flexible roll-up television screens and
computer displays one step closer to reality.
Xerox has developed a high-performance, semiconductive ink that can be used to print the
semiconductor channels of transistors at low temperatures and in open air - a requirement
for low-cost manufacturing. Most materials developed by researchers from other
organizations have required processing at high temperatures and under inert
atmospheres.
In addition to creating the semiconductive ink necessary to print the semiconductor
component of a transistor circuit, Beng Ong, a Xerox Research fellow, and his team at
the Xerox Research Centre of Canada have also developed materials for printing the conductor
and the dielectric components. Thus, all three elements necessary to make a plastic
circuit - a semiconductor, a conductor and dielectric - may now be printed using inkjet
techniques.
Companies worldwide have been competing to develop a low-cost alternative to silicon
technology that could print flexible plastic transistors as easily as printing a
newspaper. The technology could ultimately lead to inexpensive large-area devices
like flat-panel and flexible displays and low-end microelectronics such as radio frequency
identification tags.
The manufacturing dilemma
The Holy Grail for researchers who want to bring flexible plastic circuits to the masses
is a low-cost manufacturing solution that has two key elements: one, materials that can be
processed in ambient conditions, and two, compatible printing techniques. These Xerox
research developments could satisfy both these manufacturing requirements.
According to Ong, if progress continues on this research project as he expects, Xerox just
may have found the missing elements that could enable commercialized applications of
flexible printed transistors. Ong discussed these research findings in a presentation
at the Materials Research Society spring conference on April 16, 2004.
"Having developed these three critical liquid-processable materials may make it possible
to create low-cost, flexible plastic transistor circuits using common liquid-deposition
techniques such as spin coating, screen or stencil printing, offset, or inkjet printing,"
Ong said. He believes that products based on these or similar materials will be available
commercially in the near future.
Xerox's advances build on the unique polythiophene semiconductor previously designed by
Ong's team at XRCC, as well as on the Palo Alto Research Center's method for creating a
plastic semiconductor transistor array using inkjet printing, reported last fall.
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