Charge transport in π-conjugated systems

The effects on charge transport of inter chain interactions in conjugated polymers and inter shell interactions in multi-wall carbon nanotubes is studied theoretically. In the case of conjugated polymers the charge carriers are polarons, which in regions of well ordered chains extend over several such chains. When an external electric field is applied, the polarons drift rapidly through these regions. The disordered regions, however, act as barriers for charge transport and a fairly strong field is needed for the polaron to hop across these regions. Although the inter shell orbital overlap in multi-wall carbon nanotubes is larger than between polymer chains, the effective interaction is weak and the current through a multi-wall carbon nanotube is dominated by the transport along a single shell.