Ionic redox transistor from pore-spanning PPy(DBS) membranes†
We demonstrate that ion transport through polypyrrole doped with dodecylbenzenesulfonate [PPy(DBS)] formed over a pore is regulated by its electrochemical redox state. We refer to this arrangement of PPy(DBS) as an ionic redox transistor owing to its functional similarity to a bipolar junction transistor and chemical physics origins of voltage-regulated transmembrane ion transport. Our results indicate that ionic current across the polymer in its reduced state is facilitated by the affinity of cations to immobile anionic dopant (DBS) and increases with concentration and applied transmembrane potential. We report a maximum conductance of 30 μS cm−1 and a current gain of 60× as the polymer switches between oxidized (Vm > −200 mV) and reduced state (Vm < −600 mV). A demonstration of PPy(DBS) ionic redox transistor as a smart membrane separator in an electrolytic circuit is presented to illustrate its application in electrochemical energy storage devices.