Article

Giant enhancement in vertical conductivity of stacked CVD graphene sheets by self-assembled molecular layers

  • Nature Communications 5, Article number: 5461 (2014)
  • doi:10.1038/ncomms6461
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Abstract

Layer-by-layer-stacked chemical vapour deposition (CVD) graphene films find applications as transparent and conductive electrodes in solar cells, organic light-emitting diodes and touch panels. Common to lamellar-type systems with anisotropic electron delocalization, the plane-to-plane (vertical) conductivity in such systems is several orders lower than its in-plane conductivity. The poor electronic coupling between the planes is due to the presence of transfer process organic residues and trapped air pocket in wrinkles. Here we show the plane-to-plane tunnelling conductivity of stacked CVD graphene layers can be improved significantly by inserting 1-pyrenebutyric acid N-hydroxysuccinimide ester between the graphene layers. The six orders of magnitude increase in plane-to-plane conductivity is due to hole doping, orbital hybridization, planarization and the exclusion of polymer residues. Our results highlight the importance of interfacial modification for enhancing the performance of LBL-stacked CVD graphene films, which should be applicable to other types of stacked two-dimensional films.

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Acknowledgements

K.P.L. thanks MOE Tier II grant ‘Interface Engineering of Graphene Hybrids for Energy Conversion’. Grant Number: R-143-000-488-112. The Singapore National Research Foundation (NRF Award No. NRF-RF 2010-03 to C.A.N.) is kindly acknowledged for supporting this research. We thank J. WU and S.F. WANG for helpful discussions on FET device fabrication.

Author information

Author notes

    • Yanpeng Liu
    •  & Li Yuan

    These authors contributed equally to this work

Affiliations

  1. Department of Chemistry, Graphene Research Center, National University of Singapore, 3 Science Drive 3 117543 Singapore, Singapore

    • Yanpeng Liu
    • , Li Yuan
    • , Yi Zheng
    • , Linjun Li
    • , Libo Gao
    • , Nisachol Nerngchamnong
    • , Chang Tai Nai
    • , C. S. Suchand Sangeeth
    • , Christian A. Nijhuis
    •  & Kian Ping Loh
  2. NanoCore, National University of Singapore, 117576 Singapore, Singapore

    • Yanpeng Liu
  3. Department of Physics, National University of Singapore, 2 Science Drive 3, 117551 Singapore, Singapore

    • Ming Yang
    •  & Yuan Ping Feng
  4. NUS Graduate School for Integrative Sciences and Engineering, 28 Medical Drive #05-01, 117597 Singapore, Singapore

    • Chang Tai Nai

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Contributions

K.P.L. and C.A.N. supervised the project. Y.L. and L.Y. designed and performed the experiments. Y.P.L. prepared graphene samples and conducted the SAM formation. L.Y. performed the J(V) measurements. M.Y performed VASP DFT calculations. Y.Z., C.T.N. and N.N. helped to record and analyse the AFM, Raman, XPS, FTIR and UPS spectra. L.G. and L.L. helped to prepare graphene films and electrode fabrication. C.S.S.S. recorded the I–V curves of exfoliated graphene samples. All authors contributed to writing the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Christian A. Nijhuis or Kian Ping Loh.

Supplementary information

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  1. 1.

    Supplementary Information

    Supplementary Figures 1-16, Supplementary Notes 1-5 and Supplementary References

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