Unconventional Redox-Active Gate Dielectrics To Fabricate High Performance Organic Thin-Film Transistors

The fabrication of solution-processed organic thin-film transistors (OTFTs) is the cleanest root for the development of green and eco-friendly disposable technologies as a crucial need of human society in the future. Therefore, P3HT polymer based OTFTs are demonstrated here with mobility as high as 8.0 cm2/(V·s) by using an unconventional solid–electrolyte layer containing the redox-active ionic compound ethyl viologen diperchlorate (EV(ClO4)2) as the gate dielectric. A suitable negative gate bias produces a carrier density higher than 1015 holes/cm2 resulting from a reversible redox exchange reaction between EV2+ and P3HT present in the electrolyte and channel, respectively, other than the field effect and electrochemical doping. Anonymous high current (IG) between source and gate has been observed which is actually the redox-exchange current to produce large carrier density, which solely controls the operation of the transistors at very low operating voltage. A large specific capacitance (Ci = 7.1 μF/cm2) of the redox-electrolyte layer facilitates the OTFTs to operate below 1.5 V with bulk conductivity up to ∼194 S/cm and sheet conductance 40 μS/area. Our OTFT devices exhibit high reproducibility in performance and better devices parameters, including subthreshold swings down to 177 mV/dec and current ON/OFF ratios up to 107.