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Charge transport physics of organic conductors at high carrier densities

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Abstract

Conducting polymers and other organic conductors enable emerging applications in bioelectronics, neuromorphic computing, energy storage and thermoelectric devices. When used in organic electrochemical transistors or other devices, these materials are typically doped in their bulk to very high carrier densities of the order of 1020–1021 cm−3. In this regime, they show fascinating nonlinear, many-body and non-equilibrium transport phenomena that are being exploited in these applications, but whose fundamental origins remain poorly understood. In this Review, we focus on the underlying charge transport physics, examining how complex microstructure, electron–electron interactions and electron–dopant counterion interactions govern transport behaviour, including the evolution of the density of states with carrier density. We also discuss reliable experimental methods for determining carrier concentrations and measuring transport coefficients. An in-depth understanding of the charge transport physics in this high-carrier-density regime is a prerequisite for harnessing these transport phenomena in device applications.

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Fig. 1: Doping methods for organic conductors.
Fig. 2: Structure of doped conjugated polymers.
Fig. 3: Schematic illustrations of experimental methods to extract charge density.
Fig. 4: Examples of peaks in conductivity (or drain current) versus carrier concentration (or gate voltage) for organic electrochemical and electric double-layer transistors.
Fig. 5: Effect of on-site Coulomb repulsion on the DOS of organic conductors.
Fig. 6: Coulomb gaps in organic conductors.

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Acknowledgements

The authors thank the Engineering and Physical Sciences Research Council for a programme grant (EP/W017091/1) and the European Research Council (ERC) for an advanced grant (101020872). C.D.F. thanks the MRSEC programme of the US National Science Foundation for partial support under grant number DMR2011401. C.D.F. also thanks the Royal Society for a Wolfson visiting fellowship (RSWVF\R2\242019), which supported his sabbatical stay at the Cavendish Laboratory. I.E.J. thanks the Royal Society for a university research fellowship (URF\R1\231287), and H.S. thanks the Royal Society for a research professorship (RSRP\R25\1004).

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  1. Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA

    C. Daniel Frisbie

  2. Cavendish Laboratory, University of Cambridge, Cambridge, UK

    Ian. E. Jacobs, Xinglong Ren & Henning Sirringhaus

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Frisbie, C.D., Jacobs, I.E., Ren, X. et al. Charge transport physics of organic conductors at high carrier densities. Nat Rev Mater (2026). https://doi.org/10.1038/s41578-026-00897-4

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