Polymer Sequence Design of Zwitterionic Polymer/PEDOT:PSS Blend Films for Improved Charge Transport and Stability in Organic Electrochemical Transistors

Organic electrochemical transistors (OECTs) require antifouling channel materials to operate stably in biological environments. Here, we demonstrate a simple strategy to introduce antifouling functionality into PEDOT:PSS‐based OECTs using zwitterionic polymers. Homo‐, random‐, and block‐type zwitterionic polymers are synthesized and mixed with PEDOT:PSS via solution processing, enabling the fabrication of blend films without additional steps. Structural and spectroscopic analyses show that the zwitterionic polymers are retained within the films, maintaining the doping state and crystalline structure of PEDOT:PSS. Instead, differences in polymer architecture produce distinct structural features within the preserved core–shell PEDOT:PSS framework, including variations in the apparent shell thickness and, for zwitterionic (co)monomer components, the formation of an outer polymer‐rich region. These structural differences directly influence charge transport. Electrochemical and OECT measurements reveal reductions in volumetric capacitance and transconductance, mainly due to decreased apparent mobility. Protein adsorption studies further show reduced device degradation upon exposure to two proteins: bovine serum albumin and fibronectin. This blending strategy provides a practical route to antifouling, solution‐processable OECT materials for bioelectronic interfaces.