The Role of Side Chains and Hydration on Mixed Charge Transport in n-type Polymer Films

Published

March 30, 2025

Author(s)

Lucas Flagg, Lee Richter, Jokubas Surgailis, Victor Druet, Sophie Griggs, Xiaocui Wu, Stefania Moro, David Ohayon, Christina Kousseff, Adam Marks, Iuliana Petruta Maria, Hu Chen, Maximilian Moser, Giovanni Costantini, Iain McCulloch, Sahika inal

Abstract

Introducing polar ethylene glycol (EG) side chains to a conjugated polymer backbone is a well-established synthetic strategy to design organic mixed ion-electron conductors (OMIECs). However, the impact that film swelling has on mixed conduction properties has yet to be scoped, particularly for electron transporting OMIECs (n-types). Here we investigate the effect of the length of branched EG chains on mixed charge transport of n-type polymers based on a naphthalene-1,4,5,8-tetracarboxylic-diimide-bithiophene (NDI-T2) backbone. We use atomic force microscopy (AFM), grazing-incidence wide-angle X-ray scattering (GIWAXS) and scanning tunnelling microscopy (STM) to establish the similarities between the common-backbone films in dry conditions. Electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D), and in-situ GIWAXS confirm stark changes in film swelling properties when in contact with aqueous electrolyte. Lastly, these findings are correlated to organic electrochemical transistor (OECT) performance, which irrefutably shows a severe decline in mixed conduction properties brought about by unconstrained permeation of water into the OMIEC films.

Citation

Advanced Functional Materials

Pub Type

Journals

Download Paper

https://doi.org/10.1002/adma.202313121

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Keywords

polymer, transistor, electrochemical, swelling, biosensor

Citation

Flagg, L. , Richter, L. , Surgailis, J. , Druet, V. , Griggs, S. , Wu, X. , Moro, S. , Ohayon, D. , Kousseff, C. , Marks, A. , Maria, I. , Chen, H. , Moser, M. , Costantini, G. , McCulloch, I. and Inal, S. (2025), The Role of Side Chains and Hydration on Mixed Charge Transport in n-type Polymer Films, Advanced Functional Materials, [online], https://doi.org/10.1002/adma.202313121, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956857 (Accessed December 12, 2025)