Abstract
Conducting organic materials, such as doped organic polymers1, molecular conductors2,3 and emerging coordination polymers4, underpin technologies ranging from displays to flexible electronics5. Realizing high electrical conductivity in traditionally insulating organic materials necessitates tuning their electronic structure through chemical doping6. Furthermore, even organic materials that are intrinsically conductive, such as single-component molecular conductors7,8, require crystallinity for metallic behaviour. However, conducting polymers are often amorphous to aid durability and processability9. Using molecular design to produce high conductivity in undoped amorphous materials would enable tunable and robust conductivity in many applications10, but there are no intrinsically conducting organic materials that maintain high conductivity when disordered. Here we report an amorphous coordination polymer, Ni tetrathiafulvalene tetrathiolate, which displays markedly high electronic conductivity (up to 1,200 S cm−1) and intrinsic glassy-metallic behaviour. Theory shows that these properties are enabled by molecular overlap that is robust to structural perturbations. This unusual set of features results in high conductivity that is stable to humid air for weeks, pH 0–14 and temperatures up to 140 °C. These findings demonstrate that molecular design can enable metallic conductivity even in heavily disordered materials, raising fundamental questions about how metallic transport can exist without periodic structure and indicating exciting new applications for these materials.
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Data availability
All relevant data is included in the supplementary information. The raw datasets are available from the corresponding author upon request.
Code availability
The codes used in this study are available in the repository at https://github.com/damazz/NiTTFtt.
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Acknowledgements
This work was supported by the Army Research Office under grant no. W911NF-20-1-0091. D.A.M. and J.S.A. are grateful for support from the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, under award no. DE-SC0019215. H.C. and D.V.T., R.I. and D.A.M. thank the National Science Foundation for financial support under award nos CHE-1905290, CHE-1856684, and CHE-2155082, respectively. We thank N. Boynton and B. Ketter for assistance with Seebeck measurements, D. Laorenza and D. Freedman for assistance with diffuse reflectance spectroscopy, X. Jiang, Y. Fan, T. Luo and W. Lin for assistance with ICP–MS measurements, J.-A. Pan for assistance with ICP–OES measurements, H. Wu for assistance with the Dektak XT-S profilometer, A. Ritchhart for computational geometry optimizations, L. Wang for assistance with SEM and L. McNamara for help with EPR. We thank M. Goetz and the beamline staff, Y. Ding and K. Kucuk, for assistance with XAS measurements at the APS beamline 10-BM-A,B and L. C. Gallington for X-ray total scattering measurements at beamline APS 11-ID-B. The PDF measurements and analysis were supported as part of the Inorganometallic Catalyst Design Center, an Energy Frontier Research Center funded by the US DOE Basic Energy Sciences under award no. DE-SC0012702. This research used resources of APS and the Center for Nanoscale Materials, US DOE Office of Science User Facilities operated for the DOE Office of Science by Argonne National Laboratory under contract no. DE-AC02-06CH11357. Parts of this work were carried out at the Soft Matter Characterization Facility of the University of Chicago and with resources from the Research Computing Cluster. This work made use of the shared facilities at the University of Chicago Materials Research Science and Engineering Center, supported by National Science Foundation under award no. DMR-2011854.
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J.X. synthesized samples and performed their physical characterization. S.E. conducted band structure calculations. J-N.B. performed the molecular calculations. A.S.F performed and refined the structural determination. B.C. performed electrical measurements and gold depositions. T.M. and G.L.G. carried out the room-temperature Seebeck and four-probe conductivity measurements. N.Z. and R.I. collected Raman and specular reflectance IR spectra, respectively. X.S. performed the Kramers–Kronig analysis. H.C. measured variable-temperature Seebeck coefficients. Z.C. and K.W.C. collected and analysed the PDF data. J.X. and J.S.A. conceived and wrote the manuscript. B.C., S.N.P., D.V.T., J.P. and D.A.M interpreted the data and wrote the manuscript.
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J.S.A and J.X. are inventors on patent application no. 17771266 submitted by the University of Chicago that covers TTFtt-based coordination complexes and materials.
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Supplementary methods, experiments, spectra and data including the sections Synthetic procedures, Structural characterization, Composition and vibrational characterization, Physical characterization, Stability tests, Demonstration experiments, Theoretical calculations and References.
Supplementary Video 1 Demo experiments.
Experiments demonstrating the use of NiTTFtt in light-emitting circuits and the stability of these circuits to acid/base in comparison to other common conducting materials.
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Xie, J., Ewing, S., Boyn, JN. et al. Intrinsic glassy-metallic transport in an amorphous coordination polymer. Nature 611, 479–484 (2022). https://doi.org/10.1038/s41586-022-05261-4
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DOI: https://doi.org/10.1038/s41586-022-05261-4
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