In Situ Studies of the Swelling by an Electrolyte in Electrochemical Doping of Ethylene Glycol-Substituted Polythiophene

• DOI: 10.1021/acsami.2c06169
• Publication Date: 2022-06-13T15:45:20Z
• Authors: Lucas Q. Flagg; Lauren E. Asselta; Nicholas D’Antona; Tommaso Nicolini; Natalie Stingelin; Jonathan W. Onorato; Christine K. Lusc...; Ruipeng Li; Lee J. Richter
• Keywords: Polythiophene

Organic mixed ionic electronic conductors (OMIECs) have the potential to enable diverse new technologies, ranging from biosensors flexible energy storage devices and neuromorphic computing platforms. However, a study of these materials in their operating state, which convolves both passive potential-driven solvent, cation, anion ingress, is extremely difficult, inhibiting rational material design. In this report, we present novel approach situ studies electrochemical switching prototypical OMIEC based on oligoethylene glycol (oEG) substitution semicrystalline regioregular polythiophene via grazing-incidence X-ray scattering. By studying crystal lattice dry contact with electrolyte while maintaining control, can directly observe evolution crystalline domains relationship film performance an electrochemically gated transistor. Despite oEG side-chain enabling bulk uptake, find that regions are relatively hydrophobic, exhibiting little (less than one water per thiophene) swelling undoped polymer, suggesting amorphous dominate reported behavior. With applied potential, π-π separation crystals contracts lamella spacing increases balanced fashion, resulting negligible change volume. The potential-induced changes structure do not clearly correlate electrical as organic transistor, transistor strongly influenced by film.