Ion transport to temperature and gate in organic electrochemical transistors with anti-freezing hydrogel

Organic electrochemical transistors (OECTs) are useful for biochemical sensors, logic circuits, and artificial neuromorphic systems and call for insights into operation mechanisms to allow constructing complicated digital systems of high qualities. Here, we fabricate anti-freezing hydrogel based, dual-channel OECTs to probe the temperature-dependence and distance-dependence of current to investigate the ion transport. In the temperature-dependence measurement down to −30 °C, a threshold gate voltage is observed as Vth,E=0.5V, above which the electrochemical doping mode dominates. By tuning the gate voltage above Vth,E, the activation energy for hole transport is dramatically raised from 0.2 to 245.2 meV. Via the in-situ multi-point measurement, the transient response potential in neighboring channels are found not synchronous but limited by the ion transport when the ion concentration is low. The results are compared with those of OECTs based on aqueous electrolyte and reveal the operational mechanisms of OECT based on anti-freezing hydrogel.