Organic Semiconductors Made with Grease

Organic semiconductors have a good electrical conductivity, ranging between that of ordinary metals and that of insulating chemical compounds, but they have another advantage, given by their organic nature. Polyacetylene is a good example of organic semiconductors.

Among future and present applications of these materials, organic light emitting diodes (OLEDs) and solar cells are the most famous, where their organic nature contributes to energy conservation and overall efficiency.

Now, a new technique could produce some innovative plastic materials, with conductive properties greatly surpassing classical ones. The new wonder ingredient is grease, used in a chemical process that could deliver future electrical switches for transistors in RIFD tags, credit cards, electronic keys and more.

"This research brings us closer to developing organic semiconductors with electrical and physical properties far superior to those that exist today," said Richard D. McCullough, principal investigator and dean of the Mellon College of Science at Carnegie Mellon, where the research was made.

First, they combined an inherently conducting polymer (ICP) with a chemical compound resembling grease and then they deposited the hybrid material, which they called a "block copolymer," onto a greased platform.

Inherently conducting polymers are good electrical conductors on the surface of a transistor, providing the switch element for turning it on or off, but they are brittle by nature. Linking ICPs with elastic polymers resembling grease creates block copolymers that can counter the brittleness.

"These block copolymers are very promising for creating future materials, such as lightweight, thin composite films for ebook readers that you could roll up like today's newspapers," said Genevieve Sauvé, a research associate who performed recent tests on potentially commercial applications.

The new method is real novelty, also thanks to the fact that it overcomes a major problem of elastic polymers, the insulating nature, useless in conducting electricity. Making them become electrically conductive is a matter of right processing setting that the researchers have mastered.