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Cyclodextrin-threaded conjugated polyrotaxanes as insulated molecular wires with reduced interstrand interactions

Nature Materials volume 1, pages 160–164 (2002)Cite this article

Abstract

Control of intermolecular interactions1 is crucial to the exploitation of molecular semiconductors for both organic electronics2 and the viable manipulation and incorporation of single molecules3 into nano-engineered devices. Here we explore the properties of a class of materials that are engineered at a supramolecular level4,5,6,7,8,9,10 by threading a conjugated macromolecule, such as poly(para-phenylene), poly(4,4′-diphenylene vinylene) or polyfluorene through α- or β-cyclodextrin rings, so as to reduce intermolecular interactions and solid-state packing effects that red-shift and partially quench the luminescence11. Our approach preserves the fundamental semiconducting properties of the conjugated wires, and is effective at both increasing the photoluminescence efficiency and blue-shifting the emission of the conjugated cores, in the solid state, while still allowing charge-transport. We used the polymers to prepare single-layer light-emitting diodes with Ca and Al cathodes, and observed blue and green emission. The reduced tendency for polymer chains to aggregate allows solution-processing of individual polyrotaxane wires onto substrates, as revealed by scanning force microscopy.

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Figure 1: Chemical structures of the polyrotaxanes used in this work.
Figure 2: Optical properties of the polyrotaxanes and of the uninsulated wires.
Figure 3: Electroluminescence properties of insulated molecular wires.
Figure 4: Surface morphology of spin-coated polyrotaxanes and reference polymer.

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Acknowledgements

We thank the Engineering and Physical Sciences Research Council, the Royal Society and Cambridge Display Technology for financial and technical support. F.C. is a Royal Society University Research Fellow.

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Authors and Affiliations

  1. Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK

    Franco Cacialli

  2. Department of Physics, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 0HE, UK

    Franco Cacialli, Joanne S. Wilson, Clement Daniel, Carlos Silva & Richard H. Friend

  3. Department of Chemistry, University of Oxford, Dyson Perrins Laboratory, South Parks Road, Oxford, OX1 3QY, UK

    Jasper J. Michels, Michael J. O'Connell, Peter N. Taylor & Harry L. Anderson

  4. Department of Physics, Humboldt University Berlin, Invalidenstrasse 110, Berlin, D-10115, Germany

    Nikolai Severin, Paolo Samorì & Jürgen P. Rabe

  5. Istituto per la Sintesi Organica e la Fotoreattività, CNR Bologna, via Gobetti 101, Bologna, 40129, Italy

    Paolo Samorì

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Correspondence to Franco Cacialli or Harry L. Anderson.

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Cacialli, F., Wilson, J., Michels, J. et al. Cyclodextrin-threaded conjugated polyrotaxanes as insulated molecular wires with reduced interstrand interactions. Nature Mater 1, 160–164 (2002). https://doi.org/10.1038/nmat750

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