Controlling Ionic Transport in Conducting Polymers via Chemical Gating

Mixed electron/ion transport in organic materials is being explored in a wide range of technologies from bioelectronics to sensor applications. Key to applications is the control of swift ion transport for various functionalities. Our previously reported heterogeneous ion mobility in PEDOT:PSS polyelectrolyte channels raises the question whether ion transport can be separated and regulated through film nanoarchitecture. Here, we utilize differential surface energies between polyelectrolyte components to create a nanoscale hydrophilic channel in a mixed conduction thin film device where mobility is an order of magnitude higher than in the bulk and any previous measurements in this material. This interfacial channel is further gated by using different ion barrier materials of increasing hydrophobicity. Finally, we employ this mechanism to a novel sensing device where UV-induced chemical changes local to the buried channel switches on ion transport through the interfacial layer and can be sensed electronically. Understanding and controlling charge transport in conjugated polymers will enable new functionalities in future sensing and medical applications.<br/>NSF, Electronic and Photonic: Grant#1905790