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Charging and discharging of single conjugated-polymer nanoparticles

Nature Materials volume 6, pages 680–685 (2007)Cite this article

Abstract

Despite intense, long-term interest in organic semiconductors from both an applied and fundamental perspective, key aspects of the electronic properties of these materials remain poorly defined. A particularly challenging problem is the molecular nature of positive charge carriers, that is, holes or oxidized species in organics. Here, the unique ability of single-molecule spectroelectrochemistry (SMS-EC) to unravel complex electrochemical process in heterogeneous media is used to study the oxidation of nanoparticles of the conjugated polymer poly(9,9-dioctylfluorene-co-benzothiadiazole). A reversible hole-injection charging process has been observed that occurs primarily by initial injection of shallow (untrapped) holes, but soon after the injection, a small fraction of the holes becomes deeply trapped. Good agreement between experimental data and simulations strongly supports the presence of deep traps in the studied nanoparticles and highlights the ability of SMS-EC to study energetics and dynamics of deep traps in organic materials at the nanoscale.

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Figure 1: SMS-EC cell configuration and F8BT aggregates bulk electrochemistry.
Figure 2: Single-aggregate, subensemble and ensemble SMS-EC data.
Figure 3: Dependence of single-aggregate charging/discharging behaviour on potential sweep rate.
Figure 4: Dependence of E1/2 on potential sweep rate.
Figure 5: Pulsed bias experiments and charging/discharging simulations.
Figure 6: Solution-phase cyclic voltammograms of F8BT at different potential scan rates.

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Acknowledgements

This work was supported by the National Science Foundation, AFOSR, the Welch Foundation (P.F.B. and A.J.B.) and by the Basic Energy Sciences Program of the Department of Energy (P.F.B.).

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Authors and Affiliations

  1. Department of Chemistry and Biochemistry and the Center for Nano- and Molecular Science and Technology, University of Texas, Austin, Texas 78712, USA

    Rodrigo E. Palacios, Fu-Ren F. Fan, John K. Grey, Jungdon Suk, Allen J. Bard & Paul F. Barbara

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  1. Rodrigo E. Palacios
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  2. Fu-Ren F. Fan
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  3. John K. Grey
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  4. Jungdon Suk
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  5. Allen J. Bard
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Contributions

R.E.P. and F.-R.F.F. were primarily responsible for instrumental set-up, sample preparation and data acquisition. J.K.G. and J.S. were involved in the instrumental set-up for the controlled-environment SMS-EC experiments. R.E.P., F.-R.F.F., A.J.B. and P.F.B. were responsible for project planning, experiment design, data analysis and interpretation and manuscript preparation.

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Correspondence to Paul F. Barbara.

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Palacios, R., Fan, FR., Grey, J. et al. Charging and discharging of single conjugated-polymer nanoparticles. Nature Mater 6, 680–685 (2007). https://doi.org/10.1038/nmat1959

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