Organic thin-film transistors (OTFTs) have attracted extensive interests in recent years for their potential as low-cost alternatives to α-silicon transistors for low-end, large-area, and flexible electronics, for instance, Radio Frequency Identification tags and electronic papers. The economic advantage of OTFTs stems from low-cost fabrication, using common solution-based deposition techniques such as spin coating and ink jet printing. The manufacture of high-performance OTFTs requires an optimum material set (conductor, semiconductor, and dielectric) as well as appropriate processes to put the materials together in proper relationships. The latter requires a fundamental understanding of the materials compatibility and interfacial interactions.
  This talk reviews our development of a material set including semiconductor, conductor, and gate dielectrics for solution-processed OTFTs. Our novel thiophene-based polymer semiconductors not only possess high field-effect mobility (0.1-0.4 cm2/V.s) but also resolve two critical issues for roll-to-roll manufacturing: the air-stability for open air printing and easy in processing without time-consuming thermal annealing. Our conductive materials based on metal nanoparticles could be processed at a plastic-compatible temperature to yield high conductivity of 104-105 S/cm. OTFTs with electrodes printed from the nanoparticles exhibited identical performance to their counterparts employing vacuum evaporated metals. Toward all-solution processable OTFTs, a compatible and low-leakage gate dielectric will be discussed as well. Material interactions at device interfaces will be shown through device integration.