Charge-state dependent ion condensation near conjugated polymer backbones

Published

November 15, 2025

Author(s)

Dilara Meli, Quentin Thomas, Guillaume Freychet, Lucas Flagg, Iain McCulloch, David Beljonne, Lee Richter, Jonathan Rivnay

Abstract

Despite the technological appeal of organic mixed ionic/electronic conductors (OMIECs) for a range of applications, a deep understanding of the fundamentals of mixed charge transport in these materials, especially regarding the ionic component, is lacking. Herein, we show that molecular dynamics (MD) simulations of a model OMIEC representing various electrochemical gating states reveal charge-state dependent counterion condensation. X-ray diffraction calculations based on the MD data predict a measurable change in the scattering intensity at the counterion absorption edge, indicative of counterion repositioning with charging. We leverage an operando resonant X-ray scattering technique to experimentally corroborate simulated scattering and show excellent agreement between predicted and experimental data, confirming that counterions preferentially reside in the lamellar mid-plane of the crystallite at low doping, and near the polymer backbone at higher doping. Consequently, this implies that in addition to band-filling, this ion-type dependent phenomenon contributes to decreased hole mobility at high charge densities.

Citation

Materials Horizons

Pub Type

Journals

Download Paper

https://doi.org/10.1039/D5MH01939G

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Keywords

organic mixed ionic/electronic conductors, resonant x-ray scattering

Citation

Meli, D. , Thomas, Q. , Freychet, G. , Flagg, L. , McCulloch, I. , Beljonne, D. , Richter, L. and Rivnay, J. (2025), Charge-state dependent ion condensation near conjugated polymer backbones, Materials Horizons, [online], https://doi.org/10.1039/D5MH01939G, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959975 (Accessed December 11, 2025)