The electronic properties and conduction properties of polypyrrolo[3,4-c]pyrrole and polypyrrole, as well as their corresponding monomers and oligomers, have been studied by means of a DFT method at 6-31G(d) level. The bond length, electron density at bond critical points (BCP) and Wiberg bond index (WBI) were analyzed and correlated with conduction properties. The changes of electron density at BCP and WBI show that the conjugational degree is increased upon main chain-extension. The band structure and density of state (DOS) were also investigated. The result shows that the conductivity of the product polymerized at 3-position of the bicyclic molecule is better than others. The theoretical Eg is only 0.25 eV, which proposes that it can be potential conductors.

Key words: polypyrrolo[3,4-c]pyrrole, electronic structure, conductivity, band structure, density of state