Controlling Electrochemically Induced Volume Changes in Conjugated Polymers by Chemical Design: from Theory to Devices

Abstract
Electrochemically induced volume changes in organic mixed ionic-electronic conductors (OMIECs) are particularly important for their use in dynamic microfiltration systems, biomedical machinery, and electronic devices. Although significant advances have been made to maximize the dimensional changes that can be accomplished by OMIECs, there is currently limited understanding of how changes in their molecular structures impact their underpinning fundamental processes and their performance in electronic devices. Herein, a series of ethylene glycol functionalized conjugated polymers is synthesized, and their electromechanical properties are evaluated through a combined approach of experimental measurements and molecular dynamics simulations. As demonstrated, alterations in the molecular structure of OMIECs impact numerous processes occurring during their electrochemical swelling, with sidechain length shortening decreasing the number of incorporated water molecules, reducing the generated void volumes and promoting the OMIECs to undergo different phase transitions. Ultimately, the impact of these combined molecular processes is assessed in organic electrochemical transistors, revealing that careful balancing of these phenomena is required to maximize device performance.

Citation
Moser, M., Gladisch, J., Ghosh, S., Hidalgo, T. C., Ponder, J. F., Sheelamanthula, R., … McCulloch, I. (2021). Controlling Electrochemically Induced Volume Changes in Conjugated Polymers by Chemical Design: from Theory to Devices. Advanced Functional Materials, 2100723. doi:10.1002/adfm.202100723

Acknowledgements
M.M., J.G., and S.G. contributed equally to this work. The authors acknowledge financial support from KAUST, including Office of Sponsored Research (OSR) awards no. OSR-2018-CRG/CCF-3079, OSR-2019-CRG8-4086, and OSR-2018-CRG7-3749. The authors acknowledge funding from ERC Synergy Grant SC2 (610115), the European Union's Horizon 2020 research and innovation program under grant agreement no. 952911, project BOOSTER and grant agreement no. 862474, project RoLAFLEX, as well as EPSRC Project EP/T026219/1. J.G., S.G., M.B., I.Z., and E.S. acknowledge funding from Knut and Alice Wallenberg Foundation, The Wallenberg Wood Science Center (KAW 2018.0452) and the Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU No. 2009-00971). The computations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at NSC and HPC2N. A.S. acknowledges funding from the TomKat Center for Sustainable Energy at Stanford University.

Publisher
Wiley

Journal
Advanced Functional Materials

DOI
10.1002/adfm.202100723

Additional Links
https://onlinelibrary.wiley.com/doi/10.1002/adfm.202100723

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