Lodge and Frisbie have developed a novel printable, high capacitance gate insulator material that facilitates low voltage operation of OFETs on plastic substrates. The insulator is a so-called ion gel composed of an ionic liquid and a gelating triblock copolymer, polystyrene-polythethyleneoxide-polystyrene. This material may be dissolved in solvents and printed. In a collaboration with an industrial manufacturer of aerosol jet printers (Optomec, Inc.), Lodge, Frisbie, and their students have demonstrated successful low voltage operation of an array of ion-gel gated OFETs printed on flexible polyimide substrates. Every component of the OFETs was printed--the metal electrodes (gold colloidal ink), the semiconductor (poly(3-hexylthiophene), and the gate insulator (the new ion gel material). The devices work at biases less than 3V and at speeds up to 10 kHz. Efforts to optimize the ion gel material and the transistor geometry for even better performance are underway.
