High‐Performance and Environmentally Stable Organic Electrochemical Transistors Enabled by a Reprocessed Self‐Doped PEDOT Channel

ABSTRACT Organic electrochemical transistors (OECTs) require channel materials that exhibit high transconductance, strong ionic–electronic coupling, and long‐term operational stability in aqueous and humid environments. However, despite their excellent electrical performance, state‐of‐the‐art Poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) OECTs suffer from severe degradation owing to the hygroscopic PSS component, leading to a rapid loss of drain current under high temperature and humidity. In this study, planar OECTs that achieve both high electrical performance and exceptional environmental robustness by using a reprocessed self‐doped PEDOT (Re‐S‐PEDOT) channel is presented. The devices exhibit a drain current of 3.66 × 10 − 5 A µm − 1 at V G = –0.5 V and V D = –0.5 V, which is comparable to PEDOT:PSS OECTs and represents a 20‐fold improvement over the pristine self‐doped PEDOT (S‐PEDOT). Under harsh aging conditions (40°C, 85% RH), Re‐S‐PEDOT devices retained 51% of their initial drain current after one week, whereas PEDOT:PSS devices retained only 7.8%. Structural characterization demonstrated that the reprocessing procedure yielded more uniform films and improved the molecular organization, thereby contributing to enhanced ionic accessibility and device‐to‐device consistency. This study introduces a simple and scalable strategy to realize high‐performance and long‐term stable OECTs, thereby increasing the material options that can be used for reliable bioelectronic and neuromorphic applications.