Electrostatic self-assembly yields a structurally stabilized PEDOT:PSS with efficient mixed transport and high-performance OECTs

Organic electronics and organic electrochemical transistors (OECTs) are gaining importance for their potential to replicate complex biological processes of the human brain. Such devices require polymeric materials to efficiently transport and couple ionic and electronic charges in aqueous media, therefore demanding water-insoluble systems capable of efficient electronic and ionic conductions. This has created a fundamental stability-performance compromise for water-soluble conducting polymers such as poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), whereby stability has been achieved at the expense of electronic properties. Here, we demonstrate a breakthrough in structural stabilization of PEDOT:PSS through electrostatic self-assembly (ESA) that leads to the formation of an efficient mixed conductor in a hydrated state. Benefiting from the multiscale morphology control provided by ESA, PEDOT:PSS mixed conductors exhibit superior carrier mobility and high volumetric capacitance resulting in a state-of-the-art thin-film OECT figure of merit (μC∗ = 752.5 F/cmVs) in aqueous media, making this approach suitable for creating robust mixed conductors for bioelectronic applications and beyond.