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Charge transport mechanisms in inkjet-printed thin-film transistors based on two-dimensional materials

Abstract

Printed electronics using inks based on graphene and other two-dimensional materials can be used to create large-scale, flexible and wearable devices. However, the complexity of ink formulations and the polycrystalline nature of the resulting thin films have made it difficult to examine charge transport in such devices. Here we report the charge transport mechanisms of surfactant- and solvent-free inkjet-printed thin-film devices based on few-layer graphene (semimetal), molybdenum disulfide (MoS2, semiconductor) and titanium carbide MXene (Ti3C2, metal) by investigating the temperature, gate and magnetic-field dependencies of their electrical conductivity. We find that charge transport in printed few-layer MXene and MoS2 devices is dominated by the intrinsic transport mechanism of the constituent flakes: MXene exhibits a weakly localized 2D metallic behaviour at any temperature, whereas MoS2 behaves as an insulator with a crossover from 3D Mott variable-range hopping to nearest-neighbour hopping around 200 K. Charge transport in printed few-layer graphene devices is dominated by the transport mechanism between different flakes, which exhibit 3D Mott variable-range hopping conduction at any temperature.

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Fig. 1: UV–vis, AFM and TEM characterization of E2D inks.
Fig. 2: Raman spectroscopy and XPS data of E2D inks.
Fig. 3: Charge transport measurements in E2D-ink transistors.
Fig. 4: Intra-flake hopping transport in printed MoS2 devices.
Fig. 5: Inter-flake hopping transport in printed graphene devices.
Fig. 6: Intra-flake metallic transport in printed MXene devices.

Data availability

The data that support the findings of this study are available at https://data.hpc.imperial.ac.uk/ and from the corresponding author upon reasonable request.

References

  1. Torrisi, F. & Carey, T. Graphene, related two-dimensional crystals and hybrid systems for printed and wearable electronics. Nano Today 23, 73–96 (2018).

    Google Scholar 

  2. Torrisi, F. & Coleman, J. N. Electrifying inks with 2D materials. Nat. Nanotechnol. 9, 738–739 (2014).

    Google Scholar 

  3. Carey, T. et al. Fully inkjet-printed two-dimensional material field-effect heterojunctions for wearable and textile electronics. Nat. Commun. 8, 1202 (2017).

    Google Scholar 

  4. Kelly, A. G. et al. All-printed thin-film transistors from networks of liquid-exfoliated nanosheets. Science 356, 69–73 (2017).

    Google Scholar 

  5. Li, J., Naiini, M. M., Vaziri, S., Lemme, M. C. & Östling, M. Inkjet printing of MoS2. Adv. Funct. Mater. 24, 6524–531 (2014).

    Google Scholar 

  6. Karagiannidis, P. G. et al. Microfluidization of graphite and formulation of graphene-based conductive inks. ACS Nano 11, 2742–2755 (2017).

    Google Scholar 

  7. Ren, J. et al. Environmentally-friendly conductive cotton fabric as flexible strain sensor based on hot press reduced graphene oxide. Carbon 111, 622–630 (2017).

    Google Scholar 

  8. Qiang, S. et al. Wearable solid-state capacitors based on two-dimensional material all-textile heterostructures. Nanoscale 11, 9912–9919 (2019).

    Google Scholar 

  9. Parvez, K. et al. Exfoliation of graphite into graphene in aqueous solutions of inorganic salts. J. Am. Chem. Soc. 136, 6083–6091 (2014).

    Google Scholar 

  10. Lin, Z. et al. Solution-processable 2D semiconductors for high-performance large-area electronics. Nature 562, 254–258 (2018).

    Google Scholar 

  11. Paton, K. R. et al. Scalable production of large quantities of defect-free few-layer graphene by shear exfoliation in liquids. Nat. Mater. 13, 624–630 (2014).

    Google Scholar 

  12. Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation of graphite. Nat. Nanotechnol. 3, 563–568 (2008).

    Google Scholar 

  13. Hasan, T. et al. Solution-phase exfoliation of graphite for ultrafast photonics. Phys. Stat. Sol. (B) 247, 2953–2957 (2010).

    Google Scholar 

  14. Coleman, J. N. et al. Two-dimensional nanosheets produced by liquid exfoliation of layered materials. Science 331, 568–571 (2011).

    Google Scholar 

  15. Torrisi, F. et al. Inkjet-printed graphene electronics. ACS Nano 6, 2992–3006 (2012).

    Google Scholar 

  16. Kumar, D. K. et al. Scalable screen-printing manufacturing process for graphene oxide platinum free alternative counter electrodes in efficient dye sensitized solar cells. FlatChem 15, 100105 (2019).

    Google Scholar 

  17. Baker, J., Deganello, D., Gethin, D. T. & Watson, T. M. Flexographic printing of graphene nanoplatelet ink to replace platinum as counter electrode catalyst in flexible dye sensitised solar cell. Mater. Res. Innov. 18, 86–90 (2014).

    Google Scholar 

  18. Carey, T., Jones, C., Le Moal, F., Deganello, D. & Torrisi, F. Spray-coating thin films on three-dimensional surfaces for a semitransparent capacitive-touch device. ACS Appl. Mater. Interfaces 10, 19948–19956 (2018).

    Google Scholar 

  19. Sarycheva, A. et al. 2D titanium carbide (MXene) for wireless communication. Sci. Adv. 4, eaau0920 (2018).

    Google Scholar 

  20. Zhang, C. J. et al. Additive-free MXene inks and direct printing of micro-supercapacitors. Nat. Commun. 10, 1795 (2019).

    Google Scholar 

  21. Finn, D. J. et al. Inkjet deposition of liquid-exfoliated graphene and MoS2 nanosheets for printed device applications. J. Mater. Chem. C 2, 925–932 (2014).

    Google Scholar 

  22. Micallef, F. G. et al. Transparent conductors for mid-infrared liquid crystal spatial light modulators. Thin Solid Films 660, 411–420 (2018).

    Google Scholar 

  23. Bianchi, V. et al. Terahertz saturable absorbers from liquid phase exfoliation of graphite. Nat. Commun. 8, 15763 (2017).

    Google Scholar 

  24. Wang, F. et al. Graphene passively Q-switched two-micron fiber lasers. In 2012 Conference on Lasers and Electro-Optics (CLEO) 1–2 (IEEE, 2012).

  25. Singh, M., Haverinen, H. M., Dhagat, P. & Jabbour, G. E. Inkjet printing—process and its applications. Adv. Mater. 22, 673–685 (2010).

    Google Scholar 

  26. Seo, J.-W. T. et al. Fully inkjet-printed, mechanically flexible MoS2 nanosheet photodetectors. ACS Appl. Mater. Interfaces 11, 5675–5681 (2019).

    Google Scholar 

  27. Ferrari, A. C. et al. Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems. Nanoscale 7, 4598–4810 (2015).

    Google Scholar 

  28. Xue, J., Huang, S., Wang, J.-Y. & Xu, H. Q. Mott variable-range hopping transport in a MoS2 nanoflake. RSC Adv. 9, 17885–17890 (2019).

    Google Scholar 

  29. Piatti, E. et al. Multi-valley superconductivity in ion-gated MoS2 layers. Nano Lett. 18, 4821–4830 (2018).

    Google Scholar 

  30. Wu, C.-L. et al. Gate-induced metal–insulator transition in MoS2 by solid superionic conductor LaF3. Nano Lett. 18, 2387–2392 (2018).

    Google Scholar 

  31. Qiu, H. et al. Hopping transport through defect-induced localized states in molybdenum disulphide. Nat. Commun. 4, 2642 (2013).

    Google Scholar 

  32. Chen, J.-H., Jang, C., Xiao, S., Ishigami, M. & Fuhrer, M. S. Intrinsic and extrinsic performance limits of graphene devices on SiO2. Nat. Nanotechnol. 3, 206–209 (2008).

    Google Scholar 

  33. Park, C.-H. et al. Electron–phonon interactions and the intrinsic electrical resistivity of graphene. Nano Lett. 14, 1113–1119 (2014).

    Google Scholar 

  34. Gonnelli, R. S. et al. Weak localization in electric-double-layer gated few-layer graphene. 2D Mater. 4, 035006 (2017).

    Google Scholar 

  35. Miranda, A., Halim, J., Barsoum, M. W. & Lorke, A. Electronic properties of freestanding Ti3C2Tx MXene monolayers. Appl. Phys. Lett. 108, 033102 (2016).

    Google Scholar 

  36. Lipatov, A. et al. Effect of synthesis on quality, electronic properties and environmental stability of individual monolayer Ti3C2 MXene flakes. Adv. Electron. Mater. 2, 1600255 (2016).

    Google Scholar 

  37. Sangwan, V. K. & Hersam, M. C. Electronic transport in two-dimensional materials. Annu. Rev. Phys. Chem. 69, 299–325 (2018).

    Google Scholar 

  38. Akinwande, D. Two-dimensional materials: printing functional atomic layers. Nat. Nanotechnol. 12, 287–288 (2017).

    MathSciNet  Google Scholar 

  39. Kravets, V. G. et al. Spectroscopic ellipsometry of graphene and an exciton-shifted van Hove peak in absorption. Phys. Rev. B 81, 155413 (2010).

    Google Scholar 

  40. Eda, G. et al. Photoluminescence from chemically exfoliated MoS2. Nano Lett. 11, 5111–5116 (2011).

    Google Scholar 

  41. Wilcoxon, J. P., Newcomer, P. P. & Samara, G. A. Synthesis and optical properties of MoS2 and isomorphous nanoclusters in the quantum confinement regime. J. Appl. Phys. 81, 7934–7944 (1997).

    Google Scholar 

  42. Hu, M. et al. Surface functional groups and interlayer water determine the electrochemical capacitance of Ti3C2Tx MXene. ACS Nano 12, 3578–3586 (2018).

    Google Scholar 

  43. Hope, M. A. et al. NMR reveals the surface functionalisation of Ti3C2 MXene. Phys. Chem. Chem. Phys. 18, 5099–5102 (2016).

    Google Scholar 

  44. Satheeshkumar, E. et al. One-step solution processing of Ag, Au and Pd@MXene hybrids for SERS. Sci. Rep. 6, 32049 (2016).

    Google Scholar 

  45. Dillon, A. D. et al. Highly conductive optical quality solution-processed films of 2D titanium carbide. Adv. Funct. Mater. 26, 4162–4168 (2016).

    Google Scholar 

  46. El-Demellawi, J. K., Lopatin, S., Yin, J., Mohammed, O. F. & Alshareef, H. N. Tunable multipolar surface plasmons in 2D Ti3C2Tx MXene flakes. ACS Nano 12, 8485–8493 (2018).

    Google Scholar 

  47. Hantanasirisakul, K. & Gogotsi, Y. Electronic and optical properties of 2D transition metal carbides and nitrides (MXenes). Adv. Mater. 30, 1804779 (2018).

    Google Scholar 

  48. Liu, G. et al. Surface modified Ti3C2 MXene nanosheets for tumor targeting photothermal/photodynamic/chemo synergistic therapy. ACS Appl. Mater. Interfaces 9, 40077–40086 (2017).

    Google Scholar 

  49. Hoath, S. D. Fundamentals of Inkjet Printing: The Science of Inkjet and Droplets (John Wiley & Sons, 2016).

  50. Kang, R. et al. Enhanced thermal conductivity of epoxy composites filled with 2D transition metal carbides (MXenes) with ultralow loading. Sci. Rep. 9, 9135 (2019).

    Google Scholar 

  51. Schier, V., Michel, H.-J. & Halbritter, J. ARXPS-analysis of sputtered TiC, SiC and Ti0.5Si0.5C layers. Fresenius J. Anal. Chem. 346, 227–232 (1993).

    Google Scholar 

  52. García-Romeral, N., Keyhanian, M., Morales-García, Á. & Illas, F. Relating X-ray photoelectron spectroscopy data to chemical bonding in MXenes. Nanoscale Adv. 3, 2793–2801 (2021).

    Google Scholar 

  53. Natu, V. et al. A critical analysis of the X-ray photoelectron spectra of Ti3C2Tz MXenes. Matter 4, 1224–1251 (2021).

    Google Scholar 

  54. Myhra, S., Crossley, J. A. A. & Barsoum, M. W. Crystal-chemistry of the Ti3AlC2 and Ti4AlN3 layered carbide/nitride phases—characterization by XPS. J. Phys. Chem. Solids 62, 811–817 (2001).

    Google Scholar 

  55. Ferrari, A. C. & Basko, D. M. Raman spectroscopy as a versatile tool for studying the properties of graphene. Nat. Nanotechnol. 8, 235–246 (2013).

    Google Scholar 

  56. Secor, E. B., Ahn, B. Y., Gao, T. Z., Lewis, J. A. & Hersam, M. C. Rapid and versatile photonic annealing of graphene inks for flexible printed electronics. Adv. Mater. 27, 6683–6688 (2015).

    Google Scholar 

  57. Parkin, W. M. et al. Raman shifts in electron-irradiated monolayer MoS2. ACS Nano 10, 4134–4142 (2016).

    Google Scholar 

  58. Acerce, M., Voiry, D. & Chhowalla, M. Metallic 1T phase MoS2 nanosheets as supercapacitor electrode materials. Nat. Nanotechnol. 10, 313–318 (2015).

    Google Scholar 

  59. De, S., King, P. J., Lyons, P. E., Khan, U. & Coleman, J. N. Size effects and the problem with percolation in nanostructured transparent conductors. ACS Nano 4, 7064–7072 (2010).

    Google Scholar 

  60. Mott, N. F. & Davis, E. A. Electronic Processes in Noncrystalline Materials (Oxford Univ. Press, 1979).

  61. Mott, N. F. Metal-Insulator Transition (Taylor & Francis, 1990).

    Google Scholar 

  62. Beloborodov, I. S., Lopatin, A. V., Vinokur, V. M. & Efetov, K. B. Granular electronic systems. Rev. Mod. Phys. 79, 469 (2007).

    Google Scholar 

  63. Halim, J. et al. Transparent conductive two-dimensional titanium carbide epitaxial thin films. Chem. Mater. 26, 2374–2381 (2014).

    Google Scholar 

  64. Wang, H., Wu, Y., Cong, C., Shang, J. & Yu, T. Hysteresis of electronic transport in graphene transistors. ACS Nano 4, 7221–7228 (2010).

    Google Scholar 

  65. Wang, F. et al. Inter-flake quantum transport of electrons and holes in inkjet-printed graphene devices. Adv. Funct. Mater. 31, 2007478 (2021).

    Google Scholar 

  66. Carey, T. et al. Inkjet printed circuits with 2D semiconductor inks for high-performance electronics. Adv. Electron. Mater. 7, 2100112 (2021).

    Google Scholar 

  67. Li, G. et al. Equilibrium and non-equilibrium free carrier dynamics in 2D Ti3C2Tx MXenes: THz spectroscopy study. 2D Mater. 5, 035043 (2018).

    Google Scholar 

  68. Emelianova, E. V., Van der Auweraer, M., Adriaenssens, G. J. & Stesmans, A. Carrier mobility in two-dimensional disordered hopping systems. Org. Electron. 9, 29–135 (2008).

    Google Scholar 

  69. Ippolito, S. et al. Covalently interconnected transition metal dichalcogenide networks via defect engineering for high-performance electronic devices. Nat. Nanotechnol. 16, 592–598 (2021).

    Google Scholar 

  70. Halim, J. et al. Variable range hopping and thermally activated transport in molybdenum-based MXenes. Phys. Rev. B 98, 104202 (2018).

    Google Scholar 

  71. Hart, J. L. et al. Control of MXenes’ electronic properties through termination and intercalation. Nat. Commun. 10, 522 (2019).

    Google Scholar 

  72. Kovtun, A. et al. Multiscale charge transport in van der Waals thin films: reduced graphene oxide as a case study. ACS Nano 15, 2654–2667 (2021).

    Google Scholar 

  73. Kim, J. S. et al. Electrical transport properties of polymorphic MoS2. ACS Nano 10, 7500–7506 (2016).

    Google Scholar 

  74. Grimaldi, C., Ryser, P. & Strässler, S. Gauge factor of thick-film resistors: outcomes of the variable-range-hopping model. J. Appl. Phys. 88, 4164–4169 (2000).

    Google Scholar 

  75. Rodríguez, M., Bonalde, I. & Medina, E. Consistent hopping criterion in the Efros-Shklovskii regime. Phys. Rev. B 75, 235505 (2007).

    Google Scholar 

  76. Liu, C.-I. et al. Variable range hopping and nonlinear transport in monolayer epitaxial graphene grown on SiC. Semicond. Sci. Technol. 31, 105008 (2016).

    Google Scholar 

  77. Bostwick, A. et al. Quasiparticle transformation during a metal-insulator transition in graphene. Phys. Rev. Lett. 103, 056404 (2009).

    Google Scholar 

  78. Elias, D. C. et al. Control of graphene’s properties by reversible hydrogenation: evidence for graphane. Science 323, 610–613 (2009).

    Google Scholar 

  79. Adkins, C. J., Benjamin, J. D., Thomas, J. M. D., Gardner, J. W. & McGeown, A. J. Potential disorder in granular metal systems: the field effect in discontinuous metal films. J. Phys. C: Solid State Phys. 17, 4633 (1984).

    Google Scholar 

  80. Su, T.-I., Wang, C.-R., Lin, S.-T. & Rosenbaum, R. Magnetoresistance of Al70Pd22.5Re7.5 quasicrystals in the variable-range hopping regime. Phys. Rev. B 66, 054438 (2002).

    Google Scholar 

  81. Ando, T., Fowler, A. B. & Stern, F. Electronic properties of two-dimensional systems. Rev. Mod. Phys. 54, 437 (1982).

    Google Scholar 

  82. Beenakker, C. W. J. & van Houten, H. Quantum transport in semiconductor nanostructures. Solid State Phys. 44, 1–228 (1991).

    Google Scholar 

  83. Barua, S., Hatnean, M. C., Lees, M. & Balakrishnan, G. Signatures of the Kondo effect in VSe2. Sci. Rep. 7, 10964 (2017).

    Google Scholar 

  84. Pippard, A. B. Magnetoresistance in Metals (Cambridge Univ. Press, 1989).

    Google Scholar 

  85. Hikami, S., Larkin, A. I. & Nagaoka, Y. Spin-orbit interaction and magnetoresistance in the two dimensional random system. Prog. Theor. Phys. 63, 707–710 (1980).

    Google Scholar 

  86. Edmonds, M. T. et al. Spin-orbit interaction in a two-dimensional hole gas at the surface of hydrogenated diamond. Nano Lett. 15, 16–20 (2015).

    Google Scholar 

  87. Piatti, E. et al. Ambipolar suppression of superconductivity by ionic gating in optimally doped BaFe2(As,P)2 ultrathin films. Phys. Rev. Mater. 3, 044801 (2019).

    Google Scholar 

  88. Ooi, N., Rairkar, A. & Adams, J. B. Density functional study of graphite bulk and surface properties. Carbon 44, 231–242 (2006).

    Google Scholar 

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Acknowledgements

F.T. acknowledges support from EPSRC grants EP/P02534X/2, EP/R511547/1 and EP/T005106/1, and the Imperial College Collaboration Kick-Starter grant. E.P., F.G., D.D. and R.S.G. acknowledge support from the MIUR PRIN-2017 program (grant no. 2017Z8TS5B—‘Tuning and understanding quantum phases in 2D materials—Quantum2D’). L.A., K.A.P. and R.S. acknowledge support from the EU H2020 Graphene Flagship Core 3 grant no. 881603. J.M.K. acknowledges support from EPSRC grant EP/P027628/1. V.N., D.S., A.R. and A.Z. acknowledge support from the ERC CoG grant 3D2DPrint and V.N. acknowledges support from SFI Centres AMBER and IForm. A part of the electron microscopy characterization was carried out at the Advanced Microscopy Laboratory (AML) at the AMBER centre, CRANN Institute (https://www.tcd.ie/crann/aml/), Trinity College Dublin, Ireland. AML is a Science Foundation Ireland (SFI)-supported imaging and analysis centre. We acknowledge F. La Barbera (Universitá di Catania) for support in the morphological analysis of the inkjet-printed devices.

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F.T. designed the study and directed the project. E.P., D.D. and R.S.G. designed and performed the electriconic transport measurements. A.A. synthesized the graphene and MoS2 inks, fabricated the devices and performed the UV–vis, AFM, Raman and XPS characterizations. E.P. and A.A. analysed the data. F.G. and L.A. contributed to the transport measurements and data analysis. T.C. contributed to the ink formulation and device fabrication. D.S. synthesised the MXene inks. A.R. and A.Z. performed the XPS characterization and data analysis of the MXene inks. K.A.P. contributed to the device fabrication. F.T. and J.M.K. contributed to the interpretation of Raman, XPS, UV–vis and AFM data. R.S. designed the MoS2 FET device and analysed the transport data. E.P., A.A., D.D., R.S.G., V.N. and F.T. wrote the manuscript with input from all the authors.

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Correspondence to Felice Torrisi.

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Peer review information Nature Electronics thanks Lyudmila Turyanska, Jian Zhu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Sections I–XXV, Figs. 1–22 and references 1–111.

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Piatti, E., Arbab, A., Galanti, F. et al. Charge transport mechanisms in inkjet-printed thin-film transistors based on two-dimensional materials. Nat Electron 4, 893–905 (2021). https://doi.org/10.1038/s41928-021-00684-9

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