Top-Down Coarse-Grained Framework for Characterizing Mixed Conducting Polymers

Organic polymers that exhibit both ionic and electronic conduction are of interest for energy storage devices and emerging bioelectronic applications. Nevertheless, organic mixed conductors are at an early stage of development with nascent design rules and relatively few material chemistries having been experimentally characterized. Here we report a coarse-grained modeling framework that is sufficiently flexible to represent a range of mixed conducting chemistries while retaining the molecular physics necessary to interrogate structure-function relationships. A detailed overview of the framework is presented, accompanied by an applied study of the effect of hydration and oxidation levels on a representative mixed conductor. The model recapitulates experimental trends related to the macroscopic ionic and electronic conductivities, including the non-linear suppression of the electronic mobility with respect to oxidation level and the direct relationship between ionic mobility and hydration level, while revealing the complex interplay of polymer morphology, ionic-electronic coupling, and electrolyte distribution that govern these relationships. These results provide a validation of this framework for future applications in establishing structure-function relationships in this important materials class, and suggests several near-term opportunities for tailoring mixed conduction via side-chain design.