June 28, 2007 – Carnegie Mellon scientists say they have figured out a chemical process that makes block copolymers more effective electrical conductors, by treating the transistor’s silicon dioxide base layer with a “grease”-like coating.

The process — conducted under what the university says are “conditions similar to a commercial production setting” — focuses on block copolymers, created by combining inherently conducting polymers (ICP) — specifically, regioregular polythiophenes (rr-P3HTs) — with an insulating elastic polymer (poly(methylacrylate), or PMA) to make them less brittle. But that insulating polymer also makes them less effective electrical conductors — or four thin-films of block copolymers, each with different ratios of elastic polymers and deposited onto untreated silicon dioxide, tests indicated that a higher insulating polymer content meant lower conductivity.

However, pretreating the silicon dioxide platform with OTS-8, a chemical that creates a “grease-like coating,” led to “remarkable ease” conducting an electrical charge with any of the four block copolymers, according to the researchers. Even those with a 57% composition of the insulating polymer showed 10x better performance than on untreated silicon dioxide, and all were “nearly equal” to the ICPs alone on treated surfaces.

Research associate Genevieve Sauv