Poly(styrenesulfonate):Poly(3,4-ethylenedioxythiophene) (PSS:PEDOT) Based Mixed Electronic and Ionic Conducting COF

Abstract

Developing efficient mixed electronic-ionic (MEI) conductors remains a critical challenge for next-generation electronic devices. While covalent organic frameworks (COFs), with their tunable functionalities and ordered porosity, present a promising platform, only a limited number of COFs demonstrate dual conduction pathways. In this work, we integrate the MEI characteristics of PEDOT:PSS polymers into a COF architecture. A quinoline-linked COF (PSS_COF) with sulfonate-lined pore walls was synthesized via a one-pot Povarov reaction. Subsequent in-situ oxidative polymerization of PEDOT, electrostatically anchored to the sulfonated framework, yielded PEDOT:PSS_COF. Electron microscopy revealed ordered structure, with well-defined reflections in the SAED patterns distinctly indexed to the modeled crystal structure. Ultraviolet photoelectron spectroscopy (UPS) showed a 1.31 eV elevation in the valence band maximum of PEDOT:PSS_COF relative to PSS_COF, with a higher DOS near the Fermi level. This enhances electronic conductivity, from ∼10−8 to 10−2 Scm−1. The elevated HOMO level and strong EPR signal suggest the formation of polaronic species on the PEDOT chains. Electrochemical impedance spectroscopy (EIS) revealed a humidity-dependent ionic conductivity, reaching 4.6 × 10−5 Scm−1 at 95% RH and 303K, suggesting a protonic conductivity. The work demonstrates a strategy for developing high-performance MEI-conductive frameworks, by homing electronic carriers into anionic frameworks to achieve mixed-ion conduction.