Electrolyte-Polymer Interactions in Electrochemically Doped π-Conjugated Materials

Electrochemically doped π-conjugated polymers (CP) are central materials in several emerging applications, including in electrochemical energy storage and solar fuel generation (i.e., chemicals from sunlight). In these systems, electronic transport is dependent on the motion of polarons, which act as charge carriers in the CP. Here we assess how the local nanoenvironment impacts polaron properties including the surrounding dielectric environment and presence of nearby counterions from the supporting electrolyte. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) are used to determine polaron characteristics in the model n-type CP poly(NDI2OD-T2). Additionally, we perform molecular dynamics (MD) simulations to investigate the interphase of poly(NDI2OD-T2) with an electrolyte solution being perturbed by an electric field. A detailed characterization of this swelling behavior is vital for the design of CP materials that maintain functional performance under operational conditions.