Flexible screens to be printed with "negative" ink

 

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By Reuters

Posted on 22 Jan 2009 at 08:37

US researchers have developed a new type of semiconductor ink that brings bendable computer screens a step closer.

The discovery lies in the new material - a soluble semiconductor ink capable of carrying a negative electrical charge, says Philippe Inagaki, CEO of Polyera, a company that makes materials for flexible and printed electronics.

In the traditional silicon world there are two fundamental types of semiconductors: P-type, which carry a positive charge, and N-type, which carry a negative charge.

So far, most semiconductor inks, such as one developed by a team at Xerox in 2004, have only been capable of carrying a positive charge. The new ink - developed by researchers at Polyera and BASF - is an N-type.

"When you have both you make chips and circuits that are faster and more reliable and more energy-efficient. And that's a pretty big deal," Inagaki claims.

He claims the new semiconductor ink can be printed on to flexible materials, such as a thin film of plastic or even paper, using a modified inkjet printer.

"What you really want to do is print it like a newspaper," Inagaki says. "That is really fast and really cheap."

That would make it possible to print inexpensive radio-frequency identification or RFID tags on most consumer goods, helping retailers keep better track their inventory.

"This is going to enable the right kinds of printed RFIDs with sufficient performance to be really useful. It will also enable more complicated and useful kinds of flexible displays - displays you can actually bend. And it will enable new kinds of sensor technology," he adds.

In designing the new material, Antonio Facchetti, chief technology officer of the company, says he used techniques similar to those used by drug companies to discover new drug compounds. "You are looking for a new molecule," he says.

In this case, he developed a molecule that lacks electrons in its core, making it a good transporter of a negative charge. "It carries electrons very efficiently," Facchetti claims.

He claims the molecule can be dissolved in a solvent, making it possible to use it as an ink. The company plans to sell it under the brand ActivInk.

"We're at the very early stage of this industry. The first products are just starting to appear," Inagaki says. "The potential is to create something as big as the current silicon technology."