Vapor-assisted imprinting to pattern poly(3-hexylthiophene) (P3HT) film with oriented arrangement of nanofibrils and flat-on conformation of P3HT chains

Poly(3-hexylthiophene) (P3HT) film with a hierarchical ordered structure was fabricated by an approach combining vapor-assisted imprinting in a carbon disulfide (CS2) atmosphere and thermal annealing treatment. In the hierarchical ordered structure, P3HT domains are vertically arranged and the domains are constituted by uniaxially aligned P3HT nanofibrils, furthermore, the chains in it adopted flat-on conformation. The vertically arranged domains are formed by the action of capillarity, the oriented nanofibrils are induced by the crystallization nucleation of P3HT and the directional evaporation of the solvent, and the flat-on conformation of P3HT chains are induced by the enhanced intermolecular interaction of the alkyl side chains in CS2 atmosphere. The arrangement behavior of P3HT crystals and chains facilitate the bridging chains link neighboring grains with minimal distortion, while the enhanced intermolecular interaction enable the formation of larger P3HT crystals, and then reduce the quantity of grain boundary. As a result, this ordered structure provides more delocalized electrons along the direction that perpendicular to the substrate, which would result in an improvement of the carrier mobility along this direction.