Printed sub-2 V Gel-electrolyte-gated polymer transistors and circuits

The fabrication and characterization of printed ion-gel-gated poly(3-hexylthiophene) (P3HT) transistors and integrated circuits is reported, with emphasis on demonstrating both function and performance at supply voltages below 2 V. The key to achieving fast sub-2 V operation is an unusual gel electrolyte based on an ionic liquid and a gelating block copolymer. This gel electrolyte serves as the gate dielectric and has both a short polarization response time (<1 ms) and a large specific capacitance (>10 μF cm ^-2), which leads simultaneously to high output conductance (>2 mS mm^-1), low threshold voltage (<1 V) and high inverter switching frequencies (1-10 kHz). Aerosol-jet-printed inverters, ring oscillators, NAND gates, and flip-flop circuits are demonstrated. The five-stage ring oscillator operates at frequencies up to 150 Hz, corresponding to a propagation delay of 0.7 ms per stage. These printed gel electrolyte gated circuits compare favorably with other reported printed circuits that often require much larger operating voltages. Materials factors influencing the performance of the devices are discussed.