Water-processable PSS-free PEDOT:NO₃/PVA colloid for sustainable organic electrochemical transistors

Organic electrochemical transistors (OECTs) enable low-voltage amplification of ionic signals directly in aqueous media, making them potential platforms for bioelectronic interfaces, neuromorphic circuits, and biosensors. Despite significant progress, most high-performance OECTs still rely on PEDOT:PSS, where the acidic, PSS-rich formulation and large excess of insulating polyanion can limit electronic transport and raise concerns regarding long-term stability and biocompatibility. In this work, we build on our previously reported PSS-free PEDOT colloids sterically stabilized by poly(vinyl alcohol) (PVA) and investigate this water-processable dispersion as an organic mixed ionic-electronic conductor (OMIEC) channel material for OECTs. The colloid, synthesized via oxidative polymerization of EDOT in water in the presence of neutral polymer PVA, yields highly stable dispersions that form smooth, conductive thin films suitable for device fabrication. Implemented as OECT channels, these PSS-free PEDOT:NO₃/PVA films exhibit reproducible mixed ionic-electronic transport under aqueous operation with maximum transconductance values exceeding 10 mS. To the best of our knowledge, this is the first demonstration that a PVA-stabilized, PSS-free PEDOT colloid processed entirely from water can operate as an active OECT channel material, establishing a versatile route to neutral-polymer-stabilized, water-processable OMIECs for future soft and sustainable bioelectronic applications.