Plastic That Performs
Organic transistors get up to speed

Context: Organic transistors, which are made from semiconducting plastics, are cheap to manufacture. Although they enable thin, bendable electronics, so far they can't implement the fastest, most efficient circuit designs, because the plastics can't transport electrons. Instead, they rely on a flow of positive charges, or electron "holes," to pass current, which limits their use. Now, in a surprising discovery, Lay-Lay Chua at the University of Cambridge and Peter Ho at the National University of Singapore have shown that the transistors' inability to move electrons is due not to the plastic itself but to an interaction with other materials in the transistor.

Methods and Results: In a transistor, current passes through a semiconductor under the control of a gate electrode. The gate electrode is separated from the semiconductor by an insulator, typically silicon dioxide. In conventional silicon transistors, electrons pass through the semiconductor without interacting with the insulator. But in most plastic semiconductors, atoms at the interface between the insulator and the plastic trap electrons, so they can't flow through the transistor. By carefully designing an alternative insulator to replace silicon dioxide, Chua, Ho, and colleagues demonstrated that organic semiconductors can indeed conduct electrons. The discovery could make for simpler, higher-quality organic transistors that can implement the most commonly used designs.