Ionic liquid gated unipolar inverters with tunable switching voltage and excellent noise margin

Abstract

Inverters are an indispensable component of any digital circuit. We report, for the first time, an organic unipolar inverter with the driver and the load transistors gated by ionic liquids (ILs). We have devised a new design strategy that exploits the considerably low saturation regime channel resistance of the IL-gated organic field-effect transistors. This simple and scalable fabrication methodology eliminates the need for different channel dimensions of the driver and the load transistors, thereby enabling the size reduction of circuits. We have achieved a gain exceeding 10 V V⁻¹, attributable to high transistor transconductance (>5 mS), at operating voltage <1 V for the unipolar organic inverters, fabricated and characterized in the ambient environment. The switching threshold of the inverter has been tuned by up to 40% while maintaining a high gain by exploiting the strong influence of the gate electrode and the IL anion on the transistor behavior. The inverters exhibit an excellent noise margin of up to 60%, the highest noise margin reported for a low-voltage operating unipolar organic inverter. Solution-processable organic semiconductor-based high-performance, ambient-stable, and flexible-compatible inverters and subsequent integration of such devices into complex circuits will facilitate all-organic low-cost, and conformable electronic devices.