In Situ Studies of the Swelling by an Electrolyte in Electrochemical Doping of Ethylene Glycol-Substituted Polythiophene
- National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
- University of Bordeaux, Pessac (France)
- University of Bordeaux, Pessac (France); Georgia Institute of Technology, Atlanta, GA (United States)
- Univ. of Washington, Seattle, WA (United States)
- Okinawa Institute of Science and Technology Graduate University, Onna-son (Japan)
- Brookhaven National Lab. (BNL), Upton, NY (United States)
Organic mixed ionic electronic conductors (OMIECs) have the potential to enable diverse new technologies, ranging from biosensors to flexible energy storage devices and neuromorphic computing platforms. However, a study of these materials in their operating state, which convolves both passive and potential-driven solvent, cation, and anion ingress, is extremely difficult, inhibiting rational material design. In this report, we present a novel approach to the in situ studies of the electrochemical switching of a prototypical OMIEC based on oligoethylene glycol (oEG) substitution of semicrystalline regioregular polythiophene via grazing-incidence X-ray scattering. Here by studying the crystal lattice both dry and in contact with the electrolyte while maintaining potential control, we can directly observe the evolution of the crystalline domains and their relationship to film performance in an electrochemically gated transistor. Despite the oEG side-chain enabling bulk electrolyte uptake, we find that the crystalline regions are relatively hydrophobic, exhibiting little (less than one water per thiophene) swelling of the undoped polymer, suggesting that the amorphous regions dominate the reported passive swelling behavior. With applied potential, we observe that the π–π separation in the crystals contracts while the lamella spacing increases in a balanced fashion, resulting in a negligible change in the crystal volume. The potential-induced changes in the crystal structure do not clearly correlate to the electrical performance of the film as an organic electrochemical transistor, suggesting that the transistor performance is strongly influenced by the amorphous regions of the film.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); European Union (EU)
- Grant/Contract Number:
- SC0012704
- OSTI ID:
- 1890200
- Report Number(s):
- BNL-223508-2022-JAAM
- Journal Information:
- ACS Applied Materials and Interfaces, Journal Name: ACS Applied Materials and Interfaces Journal Issue: 25 Vol. 14; ISSN 1944-8244
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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