On the Working Mechanisms of Solid‐State Double‐Layer‐Dielectric‐Based Organic Field‐Effect Transistors and Their Implication for Sensors

Due to relatively low charge-carrier mobilities in organic materials, high operational voltages often have to be applied and result in severe limitations. While it has been reported that elastic polymeric dielectrics, containing a very low ion concentration, are able to overcome this bottleneck, a systematic study on the working mechanisms and their implications for sensors is still missing. Due to the possibility to form a double-layer capacitor while maintaining high insulating properties, such dielectrics enable stable low-voltage devices, giving access to high current output and high on/off ratio even below 0.5 V. Field-effect transistor devices are used to characterize this novel class of materials and to unravel their working mechanisms. To address their capability for sensors, a proof-of-concept experiment is performed, i.e., photoresponse is characterized and the field-effect dependence is analyzed. Stable low-voltage operation is a crucial issue, especially for biosensor applications which typically operate in physiological liquids and are limited by the small electrochemical window of water.