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Flexible two-dimensional indium tin oxide fabricated using a liquid metal printing technique

Nature Electronics volume 3, pages 51–58 (2020)Cite this article

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Abstract

Indium tin oxide (ITO) is a transparent conductor used in applications such as touch screens, smart windows and displays. A key limitation of ITO is its brittle nature, which prohibits its use in flexible electronics. The commercial deposition of high-quality ITO also currently relies on a costly vacuum manufacturing approach. Here we report the centimetre-scale synthesis of flexible two-dimensional ITO using a low-temperature liquid metal printing technique. The approach can directly deposit monolayer or bilayer ITO onto desired substrates, with the resulting bilayer samples offering a transparency above 99.3% and a sheet resistance as low as 5.4 kΩ □−1. We also show that the bilayer ITO features a stratified structure with a pronounced van der Waals spacing. To illustrate the capabilities of the technique, we develop a capacitive touch screen using centimetre-sized monolayer ITO sheets.

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Fig. 1: Schematic of the 2D ITO printing process and LED demonstration circuit highlighting transparency and conductivity.
Fig. 2: Material characterizations of printed 2D ITO nanosheets.
Fig. 3: Morphological and crystalline characterizations of the 2D ITO sheets.
Fig. 4: Characterization of the flexibility of 2D ITO printed on polyimide substrates.
Fig. 5: Application of 2D ITO in a capacitive touch screen.

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Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

References

  1. Dixon, S. C., Scanlon, D. O., Carmalt, C. J. & Parkin, I. P. n-Type doped transparent conducting binary oxides: an overview. J. Mater. Chem. C. 4, 6946–6961 (2016).

    Google Scholar 

  2. Zheng, Q. & Kim, J.-K. Graphene for Transparent Conductors: Synthesis, Properties and Applications Vol. 23 (Springer, 2015).

  3. Ellmer, K. Past achievements and future challenges in the development of optically transparent electrodes. Nat. Photon. 6, 809–817 (2012).

    Google Scholar 

  4. Lampert, C. M. Heat mirror coatings for energy conserving windows. Sol. Energy Mater. 6, 1–41 (1981).

    Google Scholar 

  5. Lewis, B. G. & Paine, D. C. Applications and processing of transparent conducting oxides. MRS Bull. 25, 22–27 (2000).

    Google Scholar 

  6. Greenham, N. C., Moratti, S. C., Bradley, D. D. C., Friend, R. H. & Holmes, A. B. Efficient light-emitting diodes based on polymers with high electron affinities. Nature 365, 628–630 (1993).

    Google Scholar 

  7. Yu, Z. et al. Indium tin oxide as a semiconductor material in efficient p-type dye-sensitized solar cells. NPG Asia Mater. 8, e305 (2016).

    Google Scholar 

  8. Niklasson, G. A. & Granqvist, C. G. Electrochromics for smart windows: thin films of tungsten oxide and nickel oxide, and devices based on these. J. Mater. Chem. 17, 127–156 (2007).

    Google Scholar 

  9. Guo, P., Schaller, R. D., Ketterson, J. B. & Chang, R. P. H. Ultrafast switching of tunable infrared plasmons in indium tin oxide nanorod arrays with large absolute amplitude. Nat. Photon. 10, 267–273 (2016).

    Google Scholar 

  10. Naik, G. V., Shalaev, V. M. & Boltasseva, A. Alternative plasmonic materials: beyond gold and silver. Adv. Mater. 25, 3264–3294 (2013).

    Google Scholar 

  11. Alam, M. Z., De Leon, I. & Boyd, R. W. Large optical nonlinearity of indium tin oxide in its epsilon-near-zero region. Science 352, 795–797 (2016).

    Google Scholar 

  12. Srinivasan, V., Pamula, V. K. & Fair, R. B. An integrated digital microfluidic lab-on-a-chip for clinical diagnostics on human physiological fluids. Lab Chip 4, 310–315 (2004).

    Google Scholar 

  13. Kumar, A. & Zhou, C. The race to replace tin-doped indium oxide: which material will win? ACS Nano 4, 11–14 (2010).

    Google Scholar 

  14. Shigesato, Y., Takaki, S. & Haranou, T. Crystallinity and electrical properties of tin-doped indium oxide films deposited by DC magnetron sputtering. Appl. Surf. Sci. 48-49, 269–275 (1991).

    Google Scholar 

  15. Tahar, R. B. H., Ban, T., Ohya, Y. & Takahashi, Y. Tin doped indium oxide thin films: electrical properties. J. Appl. Phys. 83, 2631–2645 (1998).

    Google Scholar 

  16. Wen, L., Sahu, B. B. & Han, J. G. Development and utility of a new 3-D magnetron source for high rate deposition of highly conductive ITO thin films near room temperature. Phys. Chem. Chem. Phys. 20, 4818–4830 (2018).

    Google Scholar 

  17. Cairns, D. R. et al. Strain-dependent electrical resistance of tin-doped indium oxide on polymer substrates. Appl. Phys. Lett. 76, 1425–1427 (2000).

    Google Scholar 

  18. Werner, T. T., Mudd, G. M. & Jowitt, S. M. Indium: key issues in assessing mineral resources and long-term supply from recycling. Trans. Inst. Min. Metall. B 124, 213–226 (2015).

    Google Scholar 

  19. Bae, S. et al. Roll-to-roll production of 30-inch graphene films for transparent electrodes. Nat. Nanotechnol. 5, 574–578 (2010).

    Google Scholar 

  20. Wang, X., Zhi, L. & Müllen, K. Transparent, conductive graphene electrodes for dye-sensitized solar cells. Nano Lett. 8, 323–327 (2008).

    Google Scholar 

  21. Wu, Z. et al. Transparent, conductive carbon nanotube films. Science 305, 1273–1276 (2004).

    Google Scholar 

  22. Hecht, D. S., Hu, L. & Irvin, G. Emerging transparent electrodes based on thin films of carbon nanotubes, graphene and metallic nanostructures. Adv. Mater. 23, 1482–1513 (2011).

    Google Scholar 

  23. Wu, H. et al. A transparent electrode based on a metal nanotrough network. Nat. Nanotechnol. 8, 421–425 (2013).

    Google Scholar 

  24. Margulis, G. Y. et al. Spray deposition of silver nanowire electrodes for semitransparent solid-state dye-sensitized solar cells. Adv. Energy Mater. 3, 1657–1663 (2013).

    Google Scholar 

  25. Morgenstern, F. S. F. et al. Ag-nanowire films coated with ZnO nanoparticles as a transparent electrode for solar cells. Appl. Phys. Lett. 99, 183307 (2011).

    Google Scholar 

  26. Khrapach, I. et al. Novel highly conductive and transparent graphene-based conductors. Adv. Mater. 24, 2844–2849 (2012).

    Google Scholar 

  27. Cao, C. et al. Nonlinear fracture toughness measurement and crack propagation resistance of functionalized graphene multilayers. Sci. Adv. 4, eaao7202 (2018).

    Google Scholar 

  28. Charalampos, A., Kaihao, Z., Matthew, R. & Sameh, T. Tailoring the mechanical properties of 2D materials and heterostructures. 2D Mater. 5, 032005 (2018).

    Google Scholar 

  29. Daeneke, T. et al. Wafer-scale synthesis of semiconducting SnO monolayers from interfacial oxide layers of metallic liquid tin. ACS Nano 11, 10974–10983 (2017).

    Google Scholar 

  30. Carey, B. J. et al. Wafer-scale two-dimensional semiconductors from printed oxide skin of liquid metals. Nat. Commun. 8, 14482 (2017).

    Google Scholar 

  31. Syed, N. et al. Wafer-sized ultrathin gallium and indium nitride nanosheets through the ammonolysis of liquid metal derived oxides. J. Am. Chem. Soc. 141, 104–108 (2019).

    Google Scholar 

  32. Syed, N. et al. Printing two-dimensional gallium phosphate out of liquid metal. Nat. Commun. 9, 3618 (2018).

    Google Scholar 

  33. Zavabeti, A. et al. A liquid metal reaction environment for the room-temperature synthesis of atomically thin metal oxides. Science 358, 332–335 (2017).

    Google Scholar 

  34. Daeneke, T. et al. Liquid metals: fundamentals and applications in chemistry. Chem. Soc. Rev. 47, 4073–4111 (2018).

    Google Scholar 

  35. Preuß, A., Adolphi, B. & Wegener, T. The kinetic of the oxidation of InSn48. Fresenius J. Anal. Chem. 353, 399–402 (1995).

    Google Scholar 

  36. Nadaud, N., Lequeux, N., Nanot, M., Jové, J. & Roisnel, T. Structural studies of tin-doped indium oxide (ITO) and In4Sn3O12. J. Solid State Chem. 135, 140–148 (1998).

    Google Scholar 

  37. Chen, Z. et al. Fabrication of highly transparent and conductive indium-tin oxide thin films with a high figure of merit via solution processing. Langmuir 29, 13836–13842 (2013).

    Google Scholar 

  38. Haacke, G. New figure of merit for transparent conductors. J. Appl. Phys. 47, 4086–4089 (1976).

    Google Scholar 

  39. Rokni, H. & Lu, W. Layer-by-layer insight into electrostatic charge distribution of few-layer graphene. Sci. Rep. 7, 42821 (2017).

    Google Scholar 

  40. Lee, P. A. & Ramakrishnan, T. Disordered electronic systems. Rev. Mod. Phys. 57, 287 (1985).

    Google Scholar 

  41. Dovesi, R. et al. CRYSTAL14: a program for the ab initio investigation of crystalline solids. Int. J. Quantum Chem. 114, 1287–1317 (2014).

    Google Scholar 

  42. Dovesi, R. et al. CRYSTAL14 User’s Manual (Univ. Torino, 2014).

  43. Becke, A. D. Density-functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 98, 5648–5652 (1993).

    Google Scholar 

  44. Laun, J., Vilela Oliveira, D. & Bredow, T. Consistent Gaussian basis sets of double-and triple-zeta valence with polarization quality of the fifth period for solid-state calculations. J. Comput. Chem. 39, 1285–1290 (2018).

    Google Scholar 

  45. CRYSTAL – Basis Sets Library (CRYSTAL - Theoretical Chemistry Group, Univ. Torino, acessed 20 November 2019); http://www.crystal.unito.it/basis-sets.php

  46. Monkhorst, H. J. & Pack, J. D. Special points for Brillouin-zone integrations. Phys. Rev. B 13, 5188 (1976).

    MathSciNet  Google Scholar 

  47. Crystallography Open Database COD ID 231009 (COD, Vilnius Univ., accessed 20 November 2019); www.crystallography.net

  48. Marezio, M. Refinement of the crystal structure of In2O3 at two wavelengths. Acta Crystallogr. 20, 723–728 (1966).

    Google Scholar 

Download references

Acknowledgements

We acknowledge technical support and instrumentation access provided by the RMIT Microscopy and Microanalysis Facility (RMMF) and MicroNano Research Facility (MNRF) at RMIT University. T.D. acknowledges funding received through the ARC DECRA scheme (DE190100100). We also acknowledge financial support received from the ARC Centre of Excellence FLEET (CE170100039). D.E. acknowledges the Scientia Fellowship scheme at the University of New South Wales. N.S. and A.Z. acknowledge funding from the Australian Government Research Training Program Scholarship scheme. S.P.R. is supported by the ARC (CE170100026). This work was also supported by computational resources provided by the Australian Government through the National Computational Infrastructure National Facility and the Pawsey Supercomputer Centre. This work was performed in part at the Melbourne Centre for Nanofabrication (MCN) in the Victorian Node of the Australian National Fabrication Facility (ANFF).

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Author notes

  1. These authors contributed equally: Robi S. Datta, Nitu Syed.

Authors and Affiliations

  1. School of Engineering, RMIT University, Melbourne, Victoria, Australia

    Robi S. Datta, Nitu Syed, Ali Zavabeti, Azmira Jannat, Md Mohiuddin, Md. Rokunuzzaman, Bao Yue Zhang, Paul Atkin, Kibret A. Messalea, Dorna Esrafilzadeh & Torben Daeneke

  2. Functional Materials and Microsystems Research Group and the Micro Nano Research Facility, RMIT University, Melbourne, Victoria, Australia

    Md. Ataur Rahman

  3. School of Chemical Engineering, University of New South Wales (UNSW), Kensington, New South Wales, Australia

    Mohammad Bagher Ghasemian & Kourosh Kalantar-Zadeh

  4. School of Science, RMIT University, Melbourne, Victoria, Australia

    Enrico Della Gaspera, Salvy P. Russo & Chris F. McConville

  5. School of Physics and Astronomy, Monash University, Monash, Victoria, Australia

    Semonti Bhattacharyya & Michael S. Fuhrer

  6. ARC Centre of Excellence in Future Low-Energy Electronics Technologies (FLEET), Monash University, Monash, Victoria, Australia

    Semonti Bhattacharyya & Michael S. Fuhrer

  7. ARC Centre of Excellence in Exciton Science, School of Science, RMIT University, Melbourne, Victoria, Australia

    Salvy P. Russo

  8. Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, New South Wales, Australia

    Dorna Esrafilzadeh

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  1. Robi S. Datta
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Contributions

The project was conceived, designed and directed by T.D., K.K.-Z. and D.E. R.S.D. and N.S. designed the synthesis methodology, experiments and device fabrications. R.S.D. synthesized monolayer 2D ITO and conducted AFM, flexible device fabrication and electrical measurements. N.S. synthesized bilayer 2D ITO, conducted a detailed AFM study of bilayer 2D ITO and fabricated devices for Hall effect measurements. A.Z. conducted TEM/SAED and HRTEM imaging and contributed to creating schematic illustrations. A.J. assisted with electronic device design and manufacture. M.M. contributed to device design and schematic illustrations. M.R. contributed to capacitive touch screen measurements. B.Y.Z. performed XPS measurements. M.A.R. contributed to four-point-probe measurements. P.A. assisted in the analysis of data and method development. K.A.M. contributed to device fabrication. M.B.G. performed cross-sectional TEM imaging. E.D.G. performed and analysed optical measurements. S.B. conducted Hall effect measurements and RIE etching. M.S.F. analysed and interpreted Hall effect data together with S.B. S.P.R. performed DFT calculations. C.F.M. contributed to the analysis of XPS data and contributed to the development of the theoretical framework. T.D., K.K.-Z., D.E., R.S.D. and N.S. analysed the results and prepared the manuscript. All authors revised the manuscript.

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Correspondence to Dorna Esrafilzadeh, Kourosh Kalantar-Zadeh or Torben Daeneke.

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Supplementary Figs. 1–13, Notes 1–3 and Table 1.

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Datta, R.S., Syed, N., Zavabeti, A. et al. Flexible two-dimensional indium tin oxide fabricated using a liquid metal printing technique. Nat Electron 3, 51–58 (2020). https://doi.org/10.1038/s41928-019-0353-8

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