Performance of Low-Operating Voltage P3HT-Based Thin-Film Transistors with Anodized Ta2O5 Insulator

Polymer thin-film transistors (TFTs) that use Ta2O5 gate insulator were fabricated on plastic substrates. The Ta2O5 gate insulator was prepared by anodizing a Ta gate electrode. Ta2O5 has a much larger relative dielectric constant (epsilon = 20 similar to 28) compared with conventional gate insulators, and it enables the polymer TFTs to operate at a lower voltage than previous devices. Poly-3-hexylthiophene (P3HT) was used as semiconducting material in the transistors. P3HT deposited by the micro-contact printing process, which uses a silicon elastomer stamp, enables the patterning of polymer layers without any photo-engraving process (PEP). The polymer FETs exhibited a field-effect mobility of 8.1 +/- 0.5 cm(2)/V(.)s and a current on/off ratio of 10(2) similar to 10(3). Furthermore, in this paper, we discuss the properties of the dielectric material as well as the P3HT-based organic transistors with a Ta2O5 gate insulator.