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A low-swelling, polymeric mixed conductor operating in aqueous electrolytes



Lee J. Richter, Tommaso Nicolini, Jokubas Surgailis, Achileas Savva, Guillaume Wantz, Olivier Dautel, Georges Hadiziioannou, Natalie Stingelin


Organic mixed conductors find use in batteries, bioelectronics technologies, neuromorphic computing and sensing. While great progress has been achieved, polymer-based mixed conductors frequently experience significant volumetric changes during ion uptake/rejection, i.e., during doping/de-doping, charging/discharging. Although ion dynamics may be enhanced in expanded networks, these volumetric changes can have undesirable consequences, e.g., negatively affecting hole/electron conduction and severely shortening device lifetime. Here, we present a new material poly[3-(6-hydroxy)hexylthiophene] (P3HHT) able to transport ions and electrons/holes, as tested in electrochemical absorption spectroscopy and organic electro-chemical transistors, that exhibits low swelling, attributed to the hydroxylated alkyl side-chain functionalization. P3HHT displays a thickness change upon passive swelling of only +2.5 %, compared to +90 % observed for the ubiquitous PEDOT:PSS, and (+10 to +15) % for polymers such as poly(2-(3,3'-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-[2,2'-bithiophen]-5-yl)thieno[3,2-b]thiophene) (p(g2T-TT)). Applying a bias pulse during swelling, this discrepancy becomes even more pronounced, with the thickness of P3HHT films changing by <10 % while the one of p(g2T-TT) structures increases by (+75 to +80) %. Importantly, the initial P3HHT film thickness is essentially restored after de-doping while p(g2T-TT) remains substantially swollen. We, thus, expand the materials-design toolbox for the creation of low-swelling soft mixed conductors with tailored properties and applications in bioelectronics and beyond.
Advanced Materials


polymer, transistor, electrochemical, organic, swelling, qcm, X-ray


Richter, L. , Nicolini, T. , Surgailis, J. , Savva, A. , Wantz, G. , Dautel, O. , Hadiziioannou, G. and Stingelin, N. (2020), A low-swelling, polymeric mixed conductor operating in aqueous electrolytes, Advanced Materials, [online], (Accessed June 13, 2024)


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Created November 30, 2020, Updated April 11, 2023