Synthesis of structurally well-defined and liquid-phase-processable graphene nanoribbons

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The properties of graphene nanoribbons (GNRs) make them good candidates for next-generation electronic materials. Whereas ‘top-down’ methods, such as the lithographical patterning of graphene and the unzipping of carbon nanotubes, give mixtures of different GNRs, structurally well-defined GNRs can be made using a ‘bottom-up’ organic synthesis approach through solution-mediated or surface-assisted cyclodehydrogenation reactions. Specifically, non-planar polyphenylene precursors were first ‘built up’ from small molecules, and then ‘graphitized’ and ‘planarized’ to yield GNRs. However, fabrication of processable and longitudinally well-extended GNRs has remained a major challenge. Here we report a bottom-up solution synthesis of long (>200 nm) liquid-phase-processable GNRs with a well-defined structure and a large optical bandgap of 1.88 eV. Self-assembled monolayers of GNRs can be observed by scanning probe microscopy, and non-contact time-resolved terahertz conductivity measurements reveal excellent charge-carrier mobility within individual GNRs. Such structurally well-defined GNRs may prove useful for fundamental studies of graphene nanostructures, as well as the development of GNR-based nanoelectronics.

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Figure 1: Structures of compounds and light-scattering characterization of precursor 2.
Figure 2: Spectroscopic characterization of GNR 3.
Figure 3: STM and AFM characterization of GNRs 3-I and 6.
Figure 4: Ultrafast photoconductivity of GNR 3-II.


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This work was financially supported by a European Research Council grant on NANOGRAPH, DFG Priority Program SPP 1355, DFG MU 334/32-1, DFG Priority Program SPP 1459, ESF Project GOSPEL (Ref Nr: 09-EuroGRAPHENE-FP-001), European Union Project SUPERIOR (PITN-GA-2009-238177), UPGRADE, and GENIUS, BELSPO IAP-PAI network Functional Supramolecular Systems and Fund of Scientific Research – Flanders. C.C. and I.A.V. acknowledge support from the Humboldt foundation in the framework of the Sofja Kovalevskaja Award. We thank L. Bertschi and R. Hafliger (Laboratory of Organic Chemistry, ETH Zürich) for high-resolution MALDI-TOF MS analysis.

Author information

K.M. and X.F. planned the project. A.N. designed and synthesized all the materials and performed standard characterization, including FTIR analysis. A.N. and Y.H. conducted UV–vis absorption spectroscopic analysis. H.Y., I.A.V. and C.C. carried out Raman spectroscopic analysis. O.I., B.L., K.S.M., T.B. and S.M. performed SPM experiments. S.A.J. conducted the THz spectroscopy experiments. M.R.H carried out solid-state NMR experiments. A.H.R.K. performed laser light-scattering experiments. X.F., M.B., G.F., S.D.F and K.M. supervised the experiments. A.N., S.A.J., C.C., G.F., O.I. and K.S.M. co-wrote the manuscript, and X.F., M.B., S.D.F. and K.M. corrected and finalized it. All authors discussed the results and implications and commented on the manuscript.

Correspondence to Xinliang Feng or Klaus Müllen.

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Narita, A., Feng, X., Hernandez, Y. et al. Synthesis of structurally well-defined and liquid-phase-processable graphene nanoribbons. Nature Chem 6, 126–132 (2014) doi:10.1038/nchem.1819

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