2. Physics of conjugated polymers and components

2.1 The role of π-electrons in conjugated polymers

Electronic conduction in the case of conductive polymers, and charge transport in general, requires the creation of free charge carriers.

At the molecular level, this implies easy ionization, either by ejecting electrons from the highest occupied electron levels of the molecule (HOMO or High Occupied Molecular Orbitals), or by capturing electrons in the lowest unoccupied electron levels (LUMO or Lowest Unoccupied Molecular Orbitals). This charge extraction or injection is particularly easy in the case of compounds with a delocalized π-electron system, i.e. compounds with a conjugated structure.