The core principle of conductive polymers lies first and foremost in the conjugated π-electron system within their molecular chains. The alternating single and double bonds in the polymer backbone form an extended conjugated system, allowing electrons to form delocalized electrons along the chain. Unlike electrons in ordinary insulators, which are bound to atoms, these electrons can move freely along the chain. This conjugated system provides the fundamental conductive pathway; the length and arrangement of the molecular structure directly affect electron migration efficiency, thus determining the polymer's basic conductivity.
Conductivity further depends on the doping mechanism, which is crucial for conductive polymers to achieve high conductivity. Doping is divided into two categories: oxidation doping and reduction doping. Both introduce holes or electrons into the polymer chain to increase the number of mobile charge carriers. Oxidation doping removes electrons to form holes, allowing positive charges to migrate along the chain; reduction doping introduces electrons to form charged carriers. Dopants can be small-molecule oxidants, acids, or ionic compounds. They interact with the polymer chain, allowing electrons or holes to move freely within the conjugated system, thereby significantly improving the material's conductivity.
