Organic semiconductors that operate through the conduction of positive charges are the first choice for use in printable electronic circuitry. A device that uses electrons instead has just joined the rankings. Transistors, the semiconductor electronic switches at the heart of any integrated circuit, come in two main flavours: p-type transistors, which switch on when a negative voltage is applied to the device's control electrode (gate); and n-type, which switch on with a positive gate voltage. Most silicon integrated circuits make use of a combination of the two types to produce complementary circuits. Such circuits can achieve higher levels of performance and yield, and lower power consumption, than can circuits made from only one type of transistor. The field of organic electronics aims to use as the semiconductor material - instead of inorganic silicon - organic molecules and polymers that can be processed from solution. That would allow large-area electronic circuits to be manufactured on flexible, plastic substrates using low-cost printing techniques. Although some p-type organic transistors have the required chemical and physical properties to produce such printable electronic circuitry, researchers have so far failed to find materials for equivalent n-type devices that would offer a comparable level of performance. On page 679 of this issue, Yan et al. describe a polymer material that achieves this feat, allowing printed complementary circuits to be produced that have unprecedented performance.
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