Design of Water-Stable PEDOT:PSS Thin Films on GOPS monolayer for High-Performance Electrochemical Transistors

Organic electrochemical transistors require organic semiconductors to efficiently transport and couple ionic and electronic charges in aqueous electrolytes. This has created a stability-performance compromise for water-soluble conducting polymers such as PEDOT:PSS that are typically blended with (3-glycidyloxypropyl)trimethoxysilane (GOPS) to enhance the water stability of the PEDOT:PSS thin films at the expense of conductivity and volumetric capacitance. Here, we demonstrate that depositing the PEDOT:PSS thin films on a GOPS monolayer, instead of blending, is sufficient to enhance the water stability of PEDOT:PSS thin films without compromising its conductivity and volumetric capacitance. Detailed characterization using time of flight secondary ion mass spectrometry (TOF-SIMS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy confirmed that the silane crosslinker was not present in the bulk of the film. This allowed an increased phase separation between PEDOT and PSS leading to the formation of enlarged PEDOT-rich domains, and thus an increase in charge carrier density, making this approach suitable for creating robust mixed conductors for bioelectronic applications and beyond.