Nanowires with unusual packing of poly(3-hexylthiophene)s induced by electric fields

We promote nanowire formation in a thin film of poly(3-hexylthiophene) (P3HT) by applying a strong electric field. Molecular packing in the formed nanowires is surprisingly different from that usually obtained by thermal annealing or from dilute solutions. In the case of electric-field annealing, the P3HT backbones are parallel to the nanowire axis; while in the former cases of thermal annealing, its backbones are perpendicular to the wire axis. Furthermore, this unusual one-dimensional nanowire exhibits improved crystallinity and electric conductivity compared to the corresponding thermally annealed sample. The growth of unusual nanowires is attributed to the introduction of dipolar interactions at the polymer ends by electric field. This kind of nanowire creates effective charge transport pathways along the intrachain route and contributes to the enhanced conductivity of the P3HT films.