High-mobility, low-power, and fast-switching organic field-effect transistors with ionic liquids

We report high-mobility rubrene single-crystal field-effect transistors with ionic-liquid (IL) electrolytes used for gate dielectric layers. As the result of fast ionic diffusion to form electric double layers, their capacitances remain more than 1μF∕cm2 even at 0.1MHz. With high carrier mobility of 1.2cm2∕Vs in the rubrene crystal, pronounced current amplification is achieved at the gate voltage of only 0.2V, which is two orders of magnitude smaller than that necessary for organic thin-film transistors with dielectric gate insulators. The results demonstrate that the IL/organic semiconductor interfaces are suited to realize low-power and fast-switching field-effect transistors without sacrificing carrier mobility in forming the solid/liquid interfaces.