Printed polymer and carbon nanotube thin film transistors with high-k barium titanate insulator

One of the difficulties in printed electronics is the robustness and reliability of the thin film transistor gate dielectrics. Thin layers are needed for low voltage operation. Proportionally thicker layers can be used if a higher permittivity (high-k) dielectric is chosen. Here we present the experimental results of partly inkjet and gravure printed thin film transistors with a commercial blend of barium titanate and poly(methyl methacrylate) (PMMA). Poly(triarylamine) (PTAA) or single walled carbon nanotube (SWCNT) inks were deposited as the semiconductor layer. Gravure printing of the dielectric material worked very well. On the other hand the SWCNT ink printing resulted in very thin layers which did not work well in transistors. Large hysteresis and high off current was present in most cases. The reference PTAA transistor measurements show that also a polymer semiconductor can work without hysteresis on top of the high-k dielectric.