Several patterning approaches have been developed to fabricate the components of polymer-based field-effect transistors (FETs). This is particularly relevant for the integration of FETs and fabrication of complex circuits. We have been developing various polyfluorene copolymers which, in the presence of a photoacid, can be photo-cross~linked. This would allow a different approach to integrate FETs to form polymeric circuits, in particular using direct UV patterning of the active semiconducting channel. In this communication we report on the synthesis and characterization of a new cross-linkable semiconducting polyfluorene and its use, in the cross-linked, insoluble form, in the fabrication of field-effect transistors, FETs. This photopatternable polymer derives from the well known poly(9,9-dioctylfluorene-alt-bithiophene), F8T2, which is one of the most studied semiconductors for FETs. We find that FETs using this cross-linked polyfluorene show p-type behaviour with a field-effect mobility which is one order of magnitude smaller than that found for similarly prepared F8T2-based FETs. We attribute this difference mainly to disorder. The surface topography of the films, before and after cross-linking, was characterized by AFM.



Reference

[1] A. Charas, L. Alcácer, A. Pimentel, J.P. Conde, J. Morgado, Chem. Pjys. Lett.,in press.