Issue 7, 2023

Role of aggregates and microstructure of mixed-ionic–electronic-conductors on charge transport in electrochemical transistors

Abstract

Synthetic efforts have delivered a library of organic mixed ionic–electronic conductors (OMIECs) with high performance in electrochemical transistors. The most promising materials are redox-active conjugated polymers with hydrophilic side chains that reach high transconductances in aqueous electrolytes due to volumetric electrochemical charging. Current approaches to improve transconductance and device stability focus mostly on materials chemistry including backbone and side chain design. However, other parameters such as the initial microstructure and microstructural rearrangements during electrochemical charging are equally important and are influenced by backbone and side chain chemistry. In this study, we employ a polymer system to investigate the fundamental electrochemical charging mechanisms of OMIECs. We couple in situ electronic charge transport measurements and spectroelectrochemistry with ex situ X-ray scattering electrochemical charging experiments and find that polymer chains planarize during electrochemical charging. Our work shows that the most effective conductivity modulation is related to electrochemical accessibility of well-ordered, interconnected aggregates that host high mobility electronic charge carriers. Electrochemical stress cycling induces microstructural changes, but we find that these aggregates can largely maintain order, providing insights on the structural stability and reversibility of electrochemical charging in these systems. This work shows the importance of material design for creating OMIECs that undergo structural rearrangements to accommodate ions and electronic charge carriers during which percolating networks are formed for efficient electronic charge transport.

Graphical abstract: Role of aggregates and microstructure of mixed-ionic–electronic-conductors on charge transport in electrochemical transistors

Supplementary files

Article information

Article type
Communication
Submitted
05 Jan 2023
Accepted
13 Apr 2023
First published
24 Apr 2023

Mater. Horiz., 2023,10, 2568-2578

Author version available

Role of aggregates and microstructure of mixed-ionic–electronic-conductors on charge transport in electrochemical transistors

G. LeCroy, C. Cendra, T. J. Quill, M. Moser, R. Hallani, J. F. Ponder, K. Stone, S. D. Kang, A. Y. Liang, Q. Thiburce, I. McCulloch, F. C. Spano, A. Giovannitti and A. Salleo, Mater. Horiz., 2023, 10, 2568 DOI: 10.1039/D3MH00017F

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