Robust graphene-based molecular devices

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Abstract

One of the main challenges to upscale the fabrication of molecular devices is to achieve a mechanically stable device with reproducible and controllable electronic features that operates at room temperature1,2. This is crucial because structural and electronic fluctuations can lead to significant changes in the transport characteristics at the electrode–molecule interface3,4. In this study, we report on the realization of a mechanically and electronically robust graphene-based molecular junction. Robustness was achieved by separating the requirements for mechanical and electronic stability at the molecular level. Mechanical stability was obtained by anchoring molecules directly to the substrate, rather than to graphene electrodes, using a silanization reaction. Electronic stability was achieved by adjusting the ππ orbitals overlap of the conjugated head groups between neighbouring molecules. The molecular devices exhibited stable current–voltage (IV) characteristics up to bias voltages of 2.0 V with reproducible transport features in the temperature range from 20 to 300 K.

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Fig. 1: Junction geometry, molecular design and electrical characterization.
Fig. 2: Electrical characterization of devices A (left), B (middle) and C (right) at 20 K exposed to the molecule BPC.
Fig. 3: Transport measurements through a BPC molecular junction (device A) at different temperatures.
Fig. 4: Transport through graphene–molecule–graphene junctions that containing the M and BPC molecule.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request. Measurements and analysis were performed in Origin and Matlab. All codes are available from the authors upon reasonable request.

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Acknowledgements

We thank C. Schönenberger for fruitful discussions. This work was partially supported by the European Commission FP7-ITN Molecular-scale Electronics: Concepts, Contacts and Stability (MOLESCO) grant (no. 606728) and the FET open project QuIET (no. 767187). This work was supported by UK Engineering and Physical Sciences Research Council Grant EP/M014452/1 and EP/N017188/1 and the European Research Council Advanced Grant (Mols@Mols). H.S. acknowledges the UK Research and Innovation for Future Leaders Fellowship no. MR/S015329/1 and the Leverhulme Trust for Leverhulme Early Career Fellowship no. ECF-2017-186. S.S. acknowledges the Leverhulme Trust for Early Career Fellowship no. ECF-2018-375. M.L.P. acknowledges the funding by the EMPAPOSTDOCS-II programme, which has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska–Curie Grant Agreement no. 754364. O.B. acknowledges technical support from the Binning and Rohrer Nanotechnology Center (BRNC).

Author information

M.E.A. conducted the measurements and performed the data analysis. O.B. and M.E.A. fabricated the devices. X.L, S.-X.L., S.D. and S.Y. provided the molecules. S.S. and H.S. provided the theory and performed the DFT calculations. M.E.A., M.L.P., H.S., H.S.J.vdZ., C.L. and M.C. designed and supervised the study. M.E.A., M.L.P., S.S. and H.S. wrote the paper. M.E.A., M.L.P., S.S., H.S. and M.C. participated in the discussion of the data. All the authors discussed the results and commented on the manuscript.

Correspondence to Shi-Xia Liu or Hatef Sadeghi or Michel Calame.

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The authors declare no competing interests.

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Peer review information Nature Nanotechnology thanks Dirk Mayer and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–9 and refs. 1–3.

Supplementary Movie 1

MD movie molecule C.

Supplementary Movie 2

MD movie molecule BPC.

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