Polymer-polymer interfaces in thin film transistors

Despite the importance of interfaces between semiconducting and dielectric polymers in thin film transistors, very little is known about the interplay between morphology and charge transport. Using a dry thin film transfer method we have fabricated polymer bilayers of semiconducting an insulating polymers that are inaccessible using spin coating. The transfer method allows the formation of polymer-polymer interfaces without the complication of solvent interactions during film formation and enables study of morphology and transport independently. For example, we have found that transferred layers of poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) PBTTT, have higher field effect mobility on some crosslinked dielectrics than directly spin-cast films. The microstructure of these bilayers has been examined using x-ray scattering and shows similar bulk ordering despite the difference in hole mobility.