David Savastano, Editor12.12.11
For many years, indium tin oxide (ITO) has been a key ingredient in a number of applications, including touch screens. ITO offers excellent conductivity as well as optical transparency.
However, there are major disadvantages to ITO, and the search for alternatives has been ongoing for almost as long as ITO has been used in these applications. ITO is brittle, making it difficult for use on flexible substrates. Indium is both expensive and in short supply.
It is also more expensive to produce devices using ITO, as sputtering or vapor deposition are more costly processes, and with the market for touch screens growing dramatically, companies are looking at ways to more economically manufacture these displays.
The goal has been to find a polymeric alternative to ITO, and much of the research has centered on Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), or PEDOT :PSS. A transparent, conductive polymer, PEDOT:PSS can be applied by a variety of processes, including printing, coating and spin coating, which offers production and cost advantages over ITO.
This research is coming to fruition. At Printed Electronics USA 2011, Eastman Kodak Company’s Industrial Materials Group and Heraeus Precious Metals GmbH & Co. KG’s Conductive Polymers Division announced they have demonstrated patterning Kodak HCF-225 Film/ESTAR™ Base using Heraeus technologies to yield completely invisible conductive patterns for a variety of touch screen applications.
“Once we attained a formulation that provided increased conductivity at very high transparency we were able to apply Kodak’s coating technology to produce very uniform, high quality transparent conductive films,” said John Bayley, European sales and marketing manager for Heraeus Precious Metals GmbH & Co. KG’s Conductive Polymers Division.
With these films commercially available as lower cost ITO alternatives Heraeus tackled the process of creating conductive patterns and soon developed Clevios™ Etch, a technology that when used with commercial photoresist materials and processes yields a completely invisible conductive pattern.
Kodak achieved this result using Clevios™ Etch and masking polymer Clevios™ SET G, or an equivalent set of photo-resist materials available from Orthogonal, Inc.
Dr. Brian Johnston, director, Kodak External Alliances, Eastman Kodak Company, noted that the gains being made in PEDOT:PSS’s conductivity is helping to drive this innovation.
“We have been working with Heraeus in the PEDOT space for many years, and now we have developed formulations that are superior with higher conductivity than past products,” Dr. Johnston said.
Dr. Johnston noted that there already is interest in this product, which is now commercially available. “Companies are sampling the product,” he said.
Dr. Stephan Kirchmeyer, head of the Functional Coatings Business Unit from the Heraeus Conductive Polymers Division, said that touch screens will soon be in virtually every electronic device.
“The market can now access a complete system that provides patterned transparent conductive films with enhanced performance at lower cost compared with current material sets and processes,” Dr. Kirchmeyer added.
By being able to print invisible traces using Clevios™ PEDOT:PSS, Kodak and Heraeus can provide a high level of transparency as well as flexibility.
“PEDOT is up to 100 times more conductive than it was 10 years ago,” Bayley added. “Polymer systems have the advantage over ITO as ITO is brittle, and PEDOT:PSS’s flexibility adds functionality for designers. Clevios™ Etch technology enables conductive traces to be etched in invisible traces, and can also be used for led displays on curved substrates.”
“The new Clevios™ Etch technology is invisible, and maintains its optical properties for touch phones,” Mark Juba, general manager, Industrial Materials Group, Eastman Kodak Company, said.
The relative ease of production is a major benefit to using PEDOT:PSS for touch screens. GSI Technologies, LLC was brought in by Kodak and Heraeus to construct a resistive touch screen demonstrator that was displayed at Heraeus’ stand at the Printed Electronics USA 2011. It was produced through conventional printing processes, including UV-cured and heat processed inks.
“It is certainly less expensive to produce by printing rather than by sputtering,” Bayley noted.
“It is readily manufactured using conventional roll-to-roll coating technology, and offers high manufacturing throughput,” Juba concluded. “This new technology opens the door to the production of a new generation of touch screens built for electronic devices using high volume web coating manufacturing processes at an economic price, when compared with the sputtering required in the manufacture of ITO films.”
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It is also more expensive to produce devices using ITO, as sputtering or vapor deposition are more costly processes, and with the market for touch screens growing dramatically, companies are looking at ways to more economically manufacture these displays.
The goal has been to find a polymeric alternative to ITO, and much of the research has centered on Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), or PEDOT :PSS. A transparent, conductive polymer, PEDOT:PSS can be applied by a variety of processes, including printing, coating and spin coating, which offers production and cost advantages over ITO.
This research is coming to fruition. At Printed Electronics USA 2011, Eastman Kodak Company’s Industrial Materials Group and Heraeus Precious Metals GmbH & Co. KG’s Conductive Polymers Division announced they have demonstrated patterning Kodak HCF-225 Film/ESTAR™ Base using Heraeus technologies to yield completely invisible conductive patterns for a variety of touch screen applications.
“Once we attained a formulation that provided increased conductivity at very high transparency we were able to apply Kodak’s coating technology to produce very uniform, high quality transparent conductive films,” said John Bayley, European sales and marketing manager for Heraeus Precious Metals GmbH & Co. KG’s Conductive Polymers Division.
With these films commercially available as lower cost ITO alternatives Heraeus tackled the process of creating conductive patterns and soon developed Clevios™ Etch, a technology that when used with commercial photoresist materials and processes yields a completely invisible conductive pattern.
Kodak achieved this result using Clevios™ Etch and masking polymer Clevios™ SET G, or an equivalent set of photo-resist materials available from Orthogonal, Inc.
Dr. Brian Johnston, director, Kodak External Alliances, Eastman Kodak Company, noted that the gains being made in PEDOT:PSS’s conductivity is helping to drive this innovation.
“We have been working with Heraeus in the PEDOT space for many years, and now we have developed formulations that are superior with higher conductivity than past products,” Dr. Johnston said.
Dr. Johnston noted that there already is interest in this product, which is now commercially available. “Companies are sampling the product,” he said.
Dr. Stephan Kirchmeyer, head of the Functional Coatings Business Unit from the Heraeus Conductive Polymers Division, said that touch screens will soon be in virtually every electronic device.
“The market can now access a complete system that provides patterned transparent conductive films with enhanced performance at lower cost compared with current material sets and processes,” Dr. Kirchmeyer added.
By being able to print invisible traces using Clevios™ PEDOT:PSS, Kodak and Heraeus can provide a high level of transparency as well as flexibility.
“PEDOT is up to 100 times more conductive than it was 10 years ago,” Bayley added. “Polymer systems have the advantage over ITO as ITO is brittle, and PEDOT:PSS’s flexibility adds functionality for designers. Clevios™ Etch technology enables conductive traces to be etched in invisible traces, and can also be used for led displays on curved substrates.”
“The new Clevios™ Etch technology is invisible, and maintains its optical properties for touch phones,” Mark Juba, general manager, Industrial Materials Group, Eastman Kodak Company, said.
The relative ease of production is a major benefit to using PEDOT:PSS for touch screens. GSI Technologies, LLC was brought in by Kodak and Heraeus to construct a resistive touch screen demonstrator that was displayed at Heraeus’ stand at the Printed Electronics USA 2011. It was produced through conventional printing processes, including UV-cured and heat processed inks.
“It is certainly less expensive to produce by printing rather than by sputtering,” Bayley noted.
“It is readily manufactured using conventional roll-to-roll coating technology, and offers high manufacturing throughput,” Juba concluded. “This new technology opens the door to the production of a new generation of touch screens built for electronic devices using high volume web coating manufacturing processes at an economic price, when compared with the sputtering required in the manufacture of ITO films.”
