Observation of Weak Counterion Size Dependence of Thermoelectric Transport in Ion Exchange Doped Conducting Polymers Across a Wide Range of Conductivities

Chen Chen, Ian E. Jacobs, Keehoon Kang, Yue Lin, Cameron Jellett, Boseok Kang, Seon Baek Lee, Yuxuan Huang, Mohammad BaloochQarai, Raja Ghosh, Martin Statz, William Wood, Xinglong Ren, Dion Tjhe, Yuanhui Sun, Xiaojian She, Yuanyuan Hu, Lang Jiang, Frank C. Spano, Iain McCullochHenning Sirringhaus

Research output: Contribution to journalArticlepeer-review


Conducting polymers are of interest for a broad range of applications from bioelectronics to thermoelectrics. The factors that govern their complex charge transport physics include the structural disorder present in these highly doped polymer films and the Coulombic interactions between the electronic charge carriers and the dopant counterions. Previous studies have shown that at low doping levels carriers are strongly trapped in the vicinity of the counterions, while at high doping levels charge transport is not limited by Coulombic trapping, which manifests itself in the conductivity being independent of the size of the dopant counterion. Here a recently developed ion exchange doping method is used to investigate the ion size dependence of a semicrystalline polythiophene-based model system across a wide range of conductivities. It is found that the regime in which the charge and thermoelectric transport is not or only weakly dependent on ion size, extends to surprisingly low conductivities. This surprising observation is explained by a heterogeneous doping that involves doping of the amorphous domains to high doping levels first before doping of the ordered, crystalline domains occurs. The study provides new insights into how the thermoelectric physics of conducting polymers evolves as a function of doping level.

Original languageEnglish
Article number2202797
JournalAdvanced Energy Materials
Issue number9
Publication statusPublished - 2023 Mar 3

Bibliographical note

Funding Information:
Financial support from the European Research Council for a Synergy grant SC2 (No. 610115) and from the Engineering and Physical Sciences Research Council (No. EP/R031894/1) is gratefully acknowledged. C.C. thanks the China Scholarship Council for financial support. H.S. acknowledges support from a Royal Society Research Professorship (RP\R1\201082), I.E.J. acknowledges funding through a Royal Society Newton International Fellowship. F.C.S. was supported by a grant from Department of Energy, DE‐SC0020046. B.K. acknowledges the International Research & Development Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (No. 2022K1A4A7A04094482).

Publisher Copyright:
© 2023 The Authors. Advanced Energy Materials published by Wiley-VCH GmbH.

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)


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