An Field-Effect Transistor Based upon Thiophene/Phenylene Co-Oligomer Nanomolecules Combined with a Composite Polymer Gate Insulator

We have studied the FET device characteristics of the thiophene/phenylene co-oligomers chosen as organic semiconductors. The FET devices were made of two kinds of co-oligomer materials with different morphologies (i.e., the thin film and crystal). We show different device fabrication procedures depending upon the difference in the morphologies. The device characteristics were also investigated on various polymer gate insulators. The composite polymer gate insulators play an important role in achieving a good device performance. More specifically, the combination of poly(vinylphenol) and poly(methyl methacrylate) turned out very effective in attaining the pinch-off at larger drain voltages. This composite gate insulator is responsible for the steady device performance as well. A normal electrical feature is maintained under a reduced (or dry) pressure where conventional polymer gate FET devices did not function normally. The relevant results are evaluated and compared. The importance of the thiophene/phenylene co-oligomers as the nanomaterials (or nanomolecules) is briefly mentioned as well.