Monday, August 17, 2009

New Polymer Semiconductors Allows Positive and Negative Charges

New organic electronics allows charges to run both ways:

A major drawback with existing organic semiconductors is most transmit only positive charges (called "holes" because the moving areas of positive charge are
actually places where an electron is missing). In the last decade a few organic
materials have been developed that can transport only electrons. But making a
working organic circuit has meant carefully layering two complicated patterns on
top of one another, one that transports electrons and another one that
transports holes.

For more than a decade Jenekhe's lab has been a leader in developing organic semiconductors that can transmit electrons. Over the past few years the group has created polymers with a donor and an acceptor part, and carefully adjusted the strength of each one. In collaboration with Watson's lab, they have now developed an organic molecule that works to transport both positive and negative charges.

"What we have shown in this paper is that you don't have to use two separate organic semiconductors," Jenekhe said. "You can use one material to create electronic circuits."

The material would allow organic transistors and other information-processing devices to be built more simply, in a way that is more similar to how inorganic circuits are now made.

The group used the new material to build a transistor designed in the same way as a silicon model and the results show that both electrons and holes move through the device quickly.

The results represent the best performance ever seen in a single-component organic polymer semiconductor, Jenekhe said. Electrons moved five to eight times faster through the UW device than in any other such polymer transistor. A circuit, which consists of two or more integrated devices, generated a voltage gain two to five times greater than previously seen in a polymer circuit.

- Brewskie

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