Abstract
Flexible electrodes that allow electrical conductance to be maintained during mechanical deformation are required for the development of wearable electronics. However, flexible electrodes based on metal thin films on elastomeric substrates can suffer from complete and unexpected electrical disconnection after the onset of mechanical fracture across the metal. Here we show that the strain-resilient electrical performance of thin-film metal electrodes under multimodal deformation can be enhanced by using a two-dimensional interlayer. Insertion of atomically thin interlayers—graphene, molybdenum disulfide or hexagonal boron nitride—induces continuous in-plane crack deflection in thin-film metal electrodes. This leads to unique electrical characteristics (termed electrical ductility) in which electrical resistance gradually increases with strain, creating extended regions of stable resistance. Our two-dimensional interlayer electrodes can maintain a low electrical resistance beyond a strain at which conventional metal electrodes would completely disconnect. We use the approach to create a flexible electroluminescent light-emitting device with an augmented strain-resilient electrical functionality and an early damage diagnosis capability.
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Acknowledgements
We acknowledge support from NSF (MRSEC DMR-1720633, ECCS-1935775, DMR-1708852 and CMMI-1554019), AFOSR (FA2386-17-1-4071), NASA ECF (NNX16AR56G), ONR YIP (N00014-17-1-2830) and LLNL (B622092). C.C. acknowledges support from a NASA Space Technology Research Fellow grant (80NSSC17K0149). The simulations were performed using the Extreme Science and Engineering Discovery Environment (XSEDE; supported by NSF grant no. OCI1053575), Blue Waters (supported by NSF awards OCI-0725070, ACI-1238993 and the State of Illinois, and, as of December 2019, by the National Geospatial-Intelligence Agency) and Frontera computing project at the Texas Advanced Computing Center (supported by NSF grant no. OAC-1818253). This research was primarily supported by the NSF through the University of Illinois at Urbana-Champaign Materials Research Science and Engineering Center (DMR-1720633). We are grateful for helpful discussions with A. J. Rosakis and J. A. Rogers.
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C.C., P.K. and S.N. conceived the idea, designed experiments and contributed to the discussion and analysis of the results. C.C. performed fabrication and characterization, and wrote the manuscript. A.T., Y.J. and N.R.A. contributed to the analytical and computational analysis. K.Y. worked on the growth of 2D materials and assisted with twist and fatigue tests. J.M.K. worked on fracture monitor videos. M.F.H. performed atomic force microscopy characterizations.
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Supplementary Information
Supplementary Figs. 1–23, Table 1, video captions 1–3 and Notes.
Supplementary Video 1
Crack development in a bare Au electrode under bending deformation.
Supplementary Video 2
Crack development in an Au/1LG electrode under bending deformation.
Supplementary Video 3
Practical functionality demonstration of flexible light-emitting devices integrated with a conventional thin-metal-film-based interconnector and a metal–2D-based interconnector.
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Cho, C., Kang, P., Taqieddin, A. et al. Strain-resilient electrical functionality in thin-film metal electrodes using two-dimensional interlayers. Nat Electron 4, 126–133 (2021). https://doi.org/10.1038/s41928-021-00538-4
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DOI: https://doi.org/10.1038/s41928-021-00538-4
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