Organic transistors detect chemicals

Researchers at Columbia University have developed a molecular transistor responsive to chemical signals, which could lead to advanced environmental and molecular sensors.

Colin Nuckolls and colleagues developed a transistor, the “wires” for which are made from single-layered polycyclic aromatic hydrocarbon molecules. The hydrocarbons self-assembled and arranged themselves single file, in a single layer along a narrow gap etched into a single-walled carbon nanotube. The team found that the molecules acted as good electrical conductors with large current modulation and high gate efficiency.

This favourable electrical activity probably came about because the molecules were in a single layer, and not stacked one upon another, the researchers say. The molecules’ conductivity changed significantly when exposed to electron-deficient molecules.

These large changes in conductivity suggest that the exposed hydrocarbons could operate as ultrasensitive chemical detectors. When a molecule of interest is detected by the hydrocarbons, the current passing through them would change, creating a detectable electrical signal.