Crystallite orientations, molecular packing disorder, and hole mobility of poly(3-hexylthiophene) thin films that are spin casted from different solvents are studied as a function of film thickness. Grazing incidence x-ray diffraction reveals that films consist of an ultrathin layer of ordered, edge-on oriented aggregates and a more disordered, face-on oriented bulk region. Diffraction and optical absorption spectroscopy elucidate the film-forming process. Field-effect hole mobility provides evidence for interconnecting aggregates as the mechanism for efficient charge transport.

• Received 14 August 2012

DOI:https://doi.org/10.1103/PhysRevB.86.205205