Comparative study of arylene bisimides substituted with imidazole side group for different dielectrics on the OFET application

We analyzed the effect of polymeric dielectric with hydroxyl and hydroxyl-free group on current–voltage characteristics of organic thin film transistor by the use of benzimidazole-derived arylene bisimide derivatives. Polyvinyl alcohol (PVA) with polar group and benzocyclobutene (BCB) with non-polar group were used as solution processed dielectric materials to compare with each other in thin film transistor application. The hydroxyl group has a significant effect on turn-on voltage and turn-off current in depletion regime due to hydroxyl group. It is observed that the surface morphology is influenced by the chemical structure of polymeric dielectric concerning surface energy. The electron field effect mobility of both arylene bisimides is enhanced by decreased surface energy of dielectric. The highest mobility was obtained by employing naphthalene bis-benzimidazole as an active layer on both dielectrics compared with perylene bis-benzimidazole semiconductor. The electrical behaviors of these semiconductors are discussed in relation to gate dielectric surface properties.