Interface morphology play an important role in controlling transport characteristics for devices based on polymer semiconductors. We modify the interface between the insulating surface and polymer film, poly(3-hexylthiophene) (P3HT), and control the interfacial molecular ordering of the polymer film by using different self assembled molecules. We correlate the changes in the optical, electrical transport, and photogenerated carrier transport to the functionalized surfaces that demonstrate different levels of molecular ordering in the polymer film at the interface of insulating surface and polymer, ranging from a uniform-disordered surface to lamella crystallite and highly oriented microdomains. © Springer Science+Business Media, LLC 2007.