Organic field-effect transistors with solution-processible thiophene/phenylene based-oligomer derivative films

摘要

Solution-processible thiophene/phenylene -based oligomer derivatives with different end substituents are presented as p-type semiconducting materials in OFETs. These films were deposited on OTS-treated SiO_2/Si or polymeric bivinyltetramethyldisiloxane-bis(benzocyclobutene) (BCB)/ITO/quartz substrates, via drop-casting and spin-casting. Synchrotron-based grazing-incidence X-ray diffraction and atomic force microscopy reveals that both drop- and spin-cast films have highly crystalline structures with edge-on molecules and parallel π-π stacking conjugated planes with respect to the substrate. In particular, temperature-dependent solubility of these materials can give a strategy for highly ordered crystalline structure in spin-cast films grown on cooler substrates, when compared to warmed solutions. Field-effect mobilities of these spin-cast films in a top-contacted electrode OFETs with BCB dielectrics are reached as high as ～0.01 cm~2/Vs.