Polyvinyl alcohol-modified PEDOT:PSS inks for 3D printing of organic electrochemical transistors and thermoelectric devices

Abstract Organic electrochemical transistors (OECTs) show great potential in the field of bioelectronics and flexible electronics due to their low voltage, high transconductance and excellent biocompatibility. In this study, we report the development of a high-performance, 3D-printable PEDOT:PSS ink by incorporating polyvinyl alcohol (PVA), achieving rheological properties, mechanical flexibility, good stretchability (25%) and strong adhesion to various substrates while maintaining an electrical conductivity above 100 S cm −1 . Fully 3D-printed organic electrochemical transistors (OECTs) based on this ink demonstrate high transconductance (5 mS), fast response time (∼12 ms), and robust mechanical stability with minimal performance degradation (<15% current loss) after 10 000 bending cycles. Moreover, the ink is readily adaptable to thermoelectric applications by combining the PEDOT:PSS-based formulation with a PVA-modified n-type PBFDO, enabling 3D-printed p–n leg modules with promising Seebeck coefficients and power outputs. A prototype 367-pair thermoelectric module exhibited a short-circuit current of 1.7 μ A and a maximum power of 35 nW under a 10 K temperature gradient, highlighting the feasibility of harvesting body heat for potential wearable applications. Overall, this work demonstrates a simple yet effective ink design strategy for PEDOT:PSS and complementary n-type polymers, paving the way toward scalable, flexible, and multifunctional printed electronics.