Floating-Gate-Coupled Two-Cell Electrochemical Transistor Augmented with Faradic Current Generated by Organic Semiconductor Ion Traps

In this work, we demonstrate a floating gate organic electrochemical transistor (OECT) formed with two cells coupled through faradic current generated by continuously trapping ions into ion traps made with an organic semiconductor. The first cell (test cell) is used for accommodating analytes, which can be discarded after a test, while the second cell (amplification cell) is designed for signal amplification and can be used many times as no contamination happens with this cell during the test. The two cells are linked with a detachable floating gate on which organic semiconductor ion traps are fabricated to generate faradic current through continuous ion-trapping and redox reactions. Our experiments showed that such faradic current is able to effectively reduce voltage loss induced by the two electrical double layers (EDL) formed at the surface of the floating gate, and consequently, device performance is improved. The obtained transconductance of such devices can match that of representative high-quality conventional OECT. The two-cell devices exhibit many advanced features over conventional OECT, such as (i) low cost owing to their partially disposable nature and (ii) independent optimization of electrolytes in the two cells to improve the device performance. The ion trapping and electrochemical redox reaction can be maintained for a sufficient long time to complete any task with the devices.