Electrons in the fast lane

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. Printed electronics devices show great potential for cheap consumer and health-care products and new applications are rapidly emerging. But device applications are limited by the fact that the plastic semiconductors currently available are almost exclusively 'hole-transporting' materials that operate via the conduction of positive charges. If an electron-transporting equivalent can be found — retaining good electrical transport properties, chemical stability and ease of processing — then it would be possible to use it in tandem with the existing plastic semiconductors to produce yet more powerful devices. Such combinations are known as 'complementary' circuitry. A team working at the Polyera Corporation labs in the United States and at BASF in Germany has produced a new material that achieves that goal. It is a highly soluble electron-transporting plastic semiconductor that exhibits unprecedented device performance, and is compatible with a broad range of printing and processing technologies.