Organic Electrochemical Transistors Based on Blend Films with Thermoresponsive Polymer

Organic electrochemical transistors (OECTs) are biocompatible devices with significant potential for biosensing. Functionalizing the channel layers is essential for improving the selectivity and sensitivity of OECT-based biosensors. A straightforward one-step fabrication method for these functionalized channel layers can simplify the production process for these devices. This study developed OECT devices based on a polymer blend of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and poly(N-isopropylacrylamide) (PNIPAM) that respond to temperature changes. Structural analyses of the blended films showed that hole transport through PEDOT is maintained even after blending, and the PNIPAM is segregated at the surface. To overcome the large chain conformational change that occurs with temperature changes, a flexible poly(ethylene glycol) diglycidyl ether (PEGDE) crosslinker is used in addition to the conventional crosslinker, (3-glycidyloxypropyl)trimethoxysilane (GOPS). As a result, the PEGDE + GOPS binary crosslinker system exhibited reversible responses to temperature cycling. These results highlight two key considerations when designing a functional mixed-conductor film based on a polymer blend system: (1) vertical phase separation and (2) proper crosslinker selection.