Portable, poster-like television screens and monitors made of a single sheet of flexible plastic may be one step closer to reality as a result of new materials that were described today by Xerox Corporation researchers.
Beng Ong, a research fellow at Xerox Research Centre of Canada, described the design and synthesis of semiconducting organic polymers that show promise for printing electronic patterns on a plastic substrate in a talk presented at the Materials Research Society’s (MRS) autumn conference in Rochester, New York.
Ong’s experimental materials are said to possess the electrical properties that would be necessary for printing plastic circuits. But in contrast to other materials that degrade quickly when exposed to oxygen, the Xerox materials are stable in air, a requisite for low-cost manufacturing under ambient conditions.
Printed plastic transistors augur an inexpensive, easy-to-manufacture alternative to silicon electronics, which are difficult to fabricate and can cost up to $10,000 per square metre. Projected applications range from identification tags on merchandise to electric paper displays.
Ong and his group developed the material by first understanding the polymer structural features responsible for limitations in existing materials, and by then developing design rules to get around those limitations. The materials were evaluated in simple devices at Xerox Research Centre of Canada (XRCC), with further testing and experimental printing at Xerox subsidiary, Palo Alto Research Centre (PARC) and other electronics firms around the world.
In his presentation to the MRS, Ong described the design and properties of new polythiophene materials, which are said to be significantly better on a variety of performance dimensions than the currently established polymers.
The experimental organic semiconductor material developed by his group is second-generation smectic liquid crystal with field effect transistor mobility of up to 0.12 square centimetres per Volt second (cm2/V.s), which is a measure of the speed of electron movement per unit of electric field. That could be up to an order of magnitude greater than other polymer benchmarks measured in the same device architecture. In addition, devices containing the experimental Xerox material exhibit little bias stress, hysteresis or instability in air.
PARC’s work builds on its experience in large area electronics based on amorphous and polycrystalline silicon. It has demonstrated jet-printed polymer field effect transistors and is developing processes to print complete active matrix arrays.
Together with PARC, Xerox is evaluating this new experimental material for suitability in a variety of printed electronics applications. If these evaluations continue to be promising, the company intends to aggressively commercialise the material through licensing to the emerging organic electronics industry.