Effects of semiconductor-dielectric interfaces on polymeric thin-film transistors

The interface between the semiconducting polymer and the gate dielectric is one of the most critical regions of a polymeric thin-film transistor. For polymeric TFTs, it is difficult to disaggregate the contributions of the electronic structure of the semiconductor and that of the dielectric because, in part, the microstructure of thin films of semiconducting polymers is strongly affected by the chemical functionality at the surface of the dielectric. We have developed a lamination technique that can be used to transfer semiconducting films formed on surfaces that yield films with high mobility to other dielectrics. We have studied films of semiconducting polymers, such as poly[5,5′-bis(3-dodecyl-2-thienyl)-2,2′-bithiophene] and poly(3-hexylthiophene) using this method. The effects of self-assembled monolayers (SAMs) formed on inorganic dielectrics on device performance are discussed. Our results suggest that mobility is mainly controlled by the structure of the semiconducting film and that the threshold voltage of TFTs may be modified through the use of SAMs.