Polythiophenes are polymerized thiophenes, a sulfur heterocycle. The parent PT is an insoluble colored solid with the formula ₙ. The rings are linked through the 2- and 5-positions. Polys have alkyl substituents at the 3- or 4-position. They are also colored solids, but tend to be soluble in organic solvents.
PTs become conductive when oxidized. The electrical conductivity results from the delocalization of electrons along the polymer backbone. Conductivity however is not the only interesting property resulting from electron delocalization. From Wikipedia
