Data from: Role of ionization energy on mixed conduction in polythiophene-derived polyelectrolyte complexes

Conjugated polyelectrolyte complexes formed by the electrostatic
compatibilization between a conjugated and an insulating polyelectrolyte
are a versatile design platform for highly processable, high-performing
polymeric mixed ion−electron conductors. While electrostatic mediation in
complexes allows for structure and property control, a fundamental
understanding of how the properties of the constituent conjugated
polyelectrolyte (CPE) translate to the resulting complex performance is
necessary for future designs. To investigate the role of CPE architecture
on the overall charge transport properties of the resulting complex
properties, here we compare a water-soluble cationic poly(alkoxythiophene)
derivative based on poly(3-alkoxy-4-methylthiophene) with an imidazolium
pendant unit and bromide counterion to an analogous complex with
poly(sodium 4-styrenesulfonate). Through spectroscopic, morphological,
electrochemical, and charge transport characterization, we find that
poly(alkoxythiophene)-based complexes exhibit high mixed conductivity,
enhanced electrochemical stability, improved doping efficiency, and lower
oxidation potential, relative to previously reported
poly(3-alkylthiophene)-based complexes, making them more suitable
candidates for electrochemical applications. Importantly, both CPE and
complex films based on the poly(3-alkoxy-4-methylthiophene) chemistry
display electronic conductivities on the order of 10−2−10−3 S/cm and
impressive ionic conductivities up to the order of 10−4 S/cm, despite the
ordered morphology of the 3-alkoxy-4-methylthiophene backbone. We make a
key observation that the enhancement of the electronic conductivity of the
CPE from an alkyl to alkoxythiophene backbone does not necessarily improve
the electronic conduction of the resulting complex as observed in previous
reports, thereby underscoring the role of complexation thermodynamics,
dielectric strength of the electrostatic complex, and complex morphology
on mixed conduction. This study provides fundamental insights governing
future design rules of mixed-conducting polyelectrolyte complexes for
next-generation energy applications.