Controlled evaporative self-assembly of hierarchically structured regioregular conjugated polymers

A toluene solution of the semiconducting conjugated polymer regioregular poly (3-hexylthiophene) (rr-P3HT) was confined in a sphere-on-flat geometry, forming an axially symmetric, capillary-held microfluid, from which the consecutive ``stick--slip'' motion of the contact line of the solution via solvent evaporation was effectively regulated. As a result, hierarchical ``snake-skin'' like structures of high regularity were obtained where each microscopic ellipsoid within the ``snake-skin'' was composed of bundles of rr-P3HT nanofibers. This facile, one-step deposition technique based on controlled evaporative self-assembly opens up a new avenue for organizing semicrystalline conjugated polymers into two-dimensional ordered patterns in a simple, cost-effective, and controllable manner.