Enhanced Performance of Solution-Processed Organic Thin-Film Transistors with a Low-Temperature-Annealed Alumina Interlayer between the Polyimide Gate Insulator and the Semiconductor

We studied a low-temperature-annealed sol–gel-derived alumina interlayer between the organic semiconductor and the organic gate insulator for high-performance organic thin-film transistors. The alumina interlayer was deposited on the polyimide gate insulator by a simple spin-coating and 200 °C-annealing process. The leakage current density decreased by the interlayer deposition: at 1 MV/cm, the leakage current densities of the polyimide and the alumina/polyimide gate insulators were 7.64 × 10^–7 and 3.01 × 10^–9 A/cm², respectively. For the first time, enhancement of the organic thin-film transistor performance by introduction of an inorganic interlayer between the organic semiconductor and the organic gate insulator was demonstrated: by introducing the interlayer, the field-effect mobility of the solution-processed organic thin-film transistor increased from 0.35 ± 0.15 to 1.35 ± 0.28 cm²/V·s. Our results suggest that inorganic interlayer deposition could be a simple and efficient surface treatment of organic gate insulators for enhancing the performance of solution-processed organic thin-film transistors