Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Covalently interconnected transition metal dichalcogenide networks via defect engineering for high-performance electronic devices


Solution-processed semiconducting transition metal dichalcogenides are at the centre of an ever-increasing research effort in printed (opto)electronics. However, device performance is limited by structural defects resulting from the exfoliation process and poor inter-flake electronic connectivity. Here, we report a new molecular strategy to boost the electrical performance of transition metal dichalcogenide-based devices via the use of dithiolated conjugated molecules, to simultaneously heal sulfur vacancies in solution-processed transition metal disulfides and covalently bridge adjacent flakes, thereby promoting percolation pathways for the charge transport. We achieve a reproducible increase by one order of magnitude in field-effect mobility (µFE), current ratio (ION/IOFF) and switching time (τS) for liquid-gated transistors, reaching 10−2 cm2 V−1 s−1, 104 and 18 ms, respectively. Our functionalization strategy is a universal route to simultaneously enhance the electronic connectivity in transition metal disulfide networks and tailor on demand their physicochemical properties according to the envisioned applications.

Your institute does not have access to this article

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Functionalization strategy for production of covalently interconnected MS2 networks.
Fig. 2: Characterization of MS2 films and networks.
Fig. 3: Electrical properties of LG-TFTs based on MoS2 films and networks.
Fig. 4: Temperature-dependent electrical characteristics.

Data availability

Source data are provided with this paper. The data that support the findings of this study are available from the corresponding author upon reasonable request.


  1. Wang, Q. H., Kalantar-Zadeh, K., Kis, A., Coleman, J. N. & Strano, M. S. Elec0tronics and optoelectronics of two-dimensional transition metal dichalcogenides. Nat. Nanotechnol. 7, 699–712 (2012).

    CAS  Google Scholar 

  2. Voiry, D., Yang, J. & Chhowalla, M. Recent strategies for improving the catalytic activity of 2D TMD nanosheets toward the hydrogen evolution reaction. Adv. Mater. 28, 6197–6206 (2016).

    CAS  Google Scholar 

  3. Chen, Y., Tan, C., Zhang, H. & Wang, L. Two-dimensional graphene analogues for biomedical applications. Chem. Soc. Rev. 44, 2681–2701 (2015).

    CAS  Google Scholar 

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

    CAS  Google Scholar 

  5. Manzeli, S., Ovchinnikov, D., Pasquier, D., Yazyev, O. V. & Kis, A. 2D transition metal dichalcogenides. Nat. Rev. Mater. 2, 17033 (2017).

    CAS  Google Scholar 

  6. Han, J. H., Kwak, M., Kim, Y. & Cheon, J. Recent advances in the solution-based preparation of two-dimensional layered transition metal chalcogenide nanostructures. Chem. Rev. 118, 6151–6188 (2018).

    CAS  Google Scholar 

  7. Backes, C. et al. Production and processing of graphene and related materials. 2D Mater. 7, 022001 (2020).

    CAS  Google Scholar 

  8. O’Neill, A., Khan, U. & Coleman, J. N. Preparation of high concentration dispersions of exfoliated MoS2 with increased flake size. Chem. Mater. 24, 2414–2421 (2012).

    Google Scholar 

  9. Yao, Y. et al. High-concentration aqueous dispersions of MoS2. Adv. Funct. Mater. 23, 3577–3583 (2013).

    CAS  Google Scholar 

  10. Bonaccorso, F., Bartolotta, A., Coleman, J. N. & Backes, C. 2D-crystal-based functional inks. Adv. Mater. 28, 6136–6166 (2016).

    CAS  Google Scholar 

  11. Bonaccorso, F. et al. Production and processing of graphene and 2d crystals. Mater. Today 15, 564–589 (2012).

    CAS  Google Scholar 

  12. Raccichini, R., Varzi, A., Passerini, S. & Scrosati, B. The role of graphene for electrochemical energy storage. Nat. Mater. 14, 271–279 (2015).

    CAS  Google Scholar 

  13. Jariwala, D., Sangwan, V. K., Lauhon, L. J., Marks, T. J. & Hersam, M. C. Emerging device applications for semiconducting two-dimensional transition metal dichalcogenides. ACS Nano 8, 1102–1120 (2014).

    CAS  Google Scholar 

  14. Ciesielski, A. & Samorì, P. Graphene via sonication assisted liquid-phase exfoliation. Chem. Soc. Rev. 43, 381–398 (2014).

    CAS  Google Scholar 

  15. Backes, C. et al. Equipartition of energy defines the size–thickness relationship in liquid-exfoliated nanosheets. ACS Nano 13, 7050–7061 (2019).

    CAS  Google Scholar 

  16. Tsai, C. et al. Electrochemical generation of sulfur vacancies in the basal plane of MoS2 for hydrogen evolution. Nat. Commun. 8, 15113 (2017).

    Google Scholar 

  17. Komsa, H.-P. et al. Two-dimensional transition metal dichalcogenides under electron irradiation: defect production and doping. Phys. Rev. Lett. 109, 035503 (2012).

    Google Scholar 

  18. McDonnell, S., Addou, R., Buie, C., Wallace, R. M. & Hinkle, C. L. Defect-dominated doping and contact resistance in MoS2. ACS Nano 8, 2880–2888 (2014).

    CAS  Google Scholar 

  19. Nicolosi, V., Chhowalla, M., Kanatzidis, M. G., Strano, M. S. & Coleman, J. N. Liquid exfoliation of layered materials. Science 340, 1226419 (2013).

    Google Scholar 

  20. Voiry, D. et al. Covalent functionalization of monolayered transition metal dichalcogenides by phase engineering. Nat. Chem. 7, 45–49 (2015).

    CAS  Google Scholar 

  21. Ippolito, S., Ciesielski, A. & Samorì, P. Tailoring the physicochemical properties of solution-processed transition metal dichalcogenides via molecular approaches. Chem. Commun. 55, 8900–8914 (2019).

    CAS  Google Scholar 

  22. Bertolazzi, S., Gobbi, M., Zhao, Y., Backes, C. & Samorì, P. Molecular chemistry approaches for tuning the properties of two-dimensional transition metal dichalcogenides. Chem. Soc. Rev. 47, 6845–6888 (2018).

    CAS  Google Scholar 

  23. Schmidt, H., Giustiniano, F. & Eda, G. Electronic transport properties of transition metal dichalcogenide field-effect devices: surface and interface effects. Chem. Soc. Rev. 44, 7715–7736 (2015).

    CAS  Google Scholar 

  24. Sim, D. M. et al. Controlled doping of vacancy-containing few-layer MoS2 via highly stable thiol-based molecular chemisorption. ACS Nano 9, 12115–12123 (2015).

    CAS  Google Scholar 

  25. Yu, X., Prévot, M. S. & Sivula, K. Multiflake thin film electronic devices of solution processed 2D MoS2 enabled by sonopolymer assisted exfoliation and surface modification. Chem. Mater. 26, 5892–5899 (2014).

    CAS  Google Scholar 

  26. Zeng, X., Hirwa, H., Metel, S., Nicolosi, V. & Wagner, V. Solution processed thin film transistor from liquid phase exfoliated MoS2 flakes. Solid State Electron. 141, 58–64 (2018).

    CAS  Google Scholar 

  27. Noriega, R. et al. A general relationship between disorder, aggregation and charge transport in conjugated polymers. Nat. Mater. 12, 1038–1044 (2013).

    CAS  Google Scholar 

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

    CAS  Google Scholar 

  29. Schilter, D. Thiol oxidation: a slippery slope. Nat. Rev. Chem. 1, 0013 (2017).

    Google Scholar 

  30. Donarelli, M., Bisti, F., Perrozzi, F. & Ottaviano, L. Tunable sulfur desorption in exfoliated MoS2 by means of thermal annealing in ultra-high vacuum. Chem. Phys. Lett. 588, 198–202 (2013).

    CAS  Google Scholar 

  31. McIntyre, N. S., Spevack, P. A., Beamson, G. & Briggs, D. Effects of argon ion bombardment on basal plane and polycrystalline MoS2. Surf. Sci. 237, L390–L397 (1990).

    CAS  Google Scholar 

  32. Mignuzzi, S. et al. Effect of disorder on Raman scattering of single-layer MoS2. Phys. Rev. B 91, 195411 (2015).

    Google Scholar 

  33. Bae, S. et al. Defect-induced vibration modes of Ar+-irradiated MoS2. Phys. Rev. Appl. 7, 024001 (2017).

    Google Scholar 

  34. Park, S. Y. et al. Highly selective and sensitive chemoresistive humidity sensors based on rGO/MoS2 van der Waals composites. J. Mater. Chem. A 6, 5016–5024 (2018).

    CAS  Google Scholar 

  35. Chow, P. K. et al. Wetting of mono and few-layered WS2 and MoS2 films supported on Si/SiO2 substrates. ACS Nano 9, 3023–3031 (2015).

    CAS  Google Scholar 

  36. Nguyen, E. P. et al. Electronic tuning of 2D MoS2 through surface functionalization. Adv. Mater. 27, 6225–6229 (2015).

    CAS  Google Scholar 

  37. Chou, S. S. et al. Ligand conjugation of chemically exfoliated MoS2. J. Am. Chem. Soc. 135, 4584–4587 (2013).

    CAS  Google Scholar 

  38. Kim, J. et al. Direct exfoliation and dispersion of two-dimensional materials in pure water via temperature control. Nat. Commun. 6, 8294 (2015).

    CAS  Google Scholar 

  39. Graetzel, M., Janssen, R. A. J., Mitzi, D. B. & Sargent, E. H. Materials interface engineering for solution-processed photovoltaics. Nature 488, 304–312 (2012).

    CAS  Google Scholar 

  40. Li, J., Naiini, M. M., Vaziri, S., Lemme, M. C. & Östling, M. Inkjet printing of MoS2. Adv. Funct. Mater. 24, 6524–6531 (2014).

    CAS  Google Scholar 

  41. Li, S.-L., Tsukagoshi, K., Orgiu, E. & Samorì, P. Charge transport and mobility engineering in two-dimensional transition metal chalcogenide semiconductors. Chem. Soc. Rev. 45, 118–151 (2015).

    Google Scholar 

  42. Wang, Y., Gali, S. M., Slassi, A., Beljonne, D. & Samorì, P. Collective dipole-dominated doping of monolayer MoS2: orientation and magnitude control via the supramolecular approach. Adv. Funct. Mater. 30, 2002846 (2020).

    CAS  Google Scholar 

  43. Chiu, F.-C. A review on conduction mechanisms in dielectric films. Adv. Mater. Sci. Eng. 2014, 578168 (2014).

    Google Scholar 

  44. Lee, K. et al. Electrical characteristics of molybdenum disulfide flakes produced by liquid exfoliation. Adv. Mater. 23, 4178–4182 (2011).

    CAS  Google Scholar 

  45. Sze, S. M. & Ng, K. K. Physics of Semiconductor Devices (John Wiley & Sons, 2006).

  46. Vladimirov, I. et al. Bulk transport and contact limitation of MoS2 multilayer flake transistors untangled via temperature-dependent transport measurements. Physica Status Solidi A 212, 2059–2067 (2015).

    CAS  Google Scholar 

  47. Higgins, T. M. et al. Electrolyte-gated n-type transistors produced from aqueous inks of WS2 nanosheets. Adv. Funct. Mater. 29, 1804387 (2019).

    Google Scholar 

  48. Anichini, C. et al. Chemical sensing with 2D materials. Chem. Soc. Rev. 47, 4860–4908 (2018).

    CAS  Google Scholar 

  49. Akinwande, D., Petrone, N. & Hone, J. Two-dimensional flexible nanoelectronics. Nat. Commun. 5, 5678 (2014).

    CAS  Google Scholar 

Download references


We acknowledge funding from the European Commission through the Graphene Flagship, the ERC Grants SUPRA2DMAT (GA-833707), FUTURE-PRINT (GA-694101), Hetero2D and GSYNCOR, the EU Grant Neurofibres, the Agence Nationale de la Recherche through the Labex projects CSC (ANR-10-LABX-0026 CSC) and NIE (ANR-11-LABX-0058 NIE) within the Investissement d’Avenir programme (ANR-10-120 IDEX-0002-02), the International Center for Frontier Research in Chemistry (icFRC), EPSRC Grants EP/K01711X/1, EP/K017144/1, EP/N010345/1 and EP/L016057/1, and the Faraday Institution. The HAADF-STEM characterization was carried out at the Advanced Microscopy Laboratory (Dublin), a Science Foundation Ireland (SFI) supported centre.

Author information

Authors and Affiliations



S.I. and P.S. conceived the experiments and designed the study. A.G.K., Z.B., L.L., Y.A.S., A.C.F. and J.N.C. produced the raw materials and characterized them by spectroscopic and electrochemical techniques. S.I. designed and performed the multiscale characterizations on the final functionalized materials. R.F.O. and M.-A.S. designed and performed the charge-carrier transport measurements and studies. D.I. carried out the NMR measurements and analysis. A.R., C.D. and V.N. designed and performed the HAADF-STEM investigations. All authors discussed the results and contributed to the interpretation of data. S.I., R.F.O. and P.S. co-wrote the paper with input from all co-authors.

Corresponding author

Correspondence to Paolo Samorì.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Nanotechnology thanks Damien Voiry and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Spectroscopic and morphological characterization of solution-processed MS2.

a, UV-Vis spectra (solution). b, Raman spectra (film). c, Statistical AFM analysis performed on 300 individual MS2 flakes and comparison with values estimated via UV-Vis spectroscopy. d, Typical SEM image of drop-cast MoS2 flakes.

Extended Data Fig. 2 HAADF-STEM investigation.

HAADF-STEM images and related histograms of Mo-Mo distance for the a, basal plane of LPE-MoS2, b, edge of LPE-MoS2, c, basal plane of MC-MoS2 and d, basal plane of CVD-MoS2. The histograms show a similar average Mo-Mo distance for the basal plane of all samples, with a significant decrease ~30 pm for the edge of LPE-MoS2, pointing to a higher defect density.

Extended Data Fig. 3 XPS analysis.

a, Sulfur/Metal XPS ratio before and after exposure to BDT molecules for MoS2, WS2 and ReS2. b, Summary of the XPS constraints (spin-orbit splitting and intensity ratio) implemented for the fitting of Mo3d, Re4f, W4f and S2p regions, before and after exposure to BDT molecules.

Extended Data Fig. 4 Ex-situ functionalization with BDT.

a, Schematic illustration for the ex-situ functionalization of MS2 inks with BDT. b, Outcome of stability test for pristine and BDT-functionalized MoS2 ink, along with the related zeta potential values. c, Optical image of a IDE device covered with BDT-functionalized MoS2 ink via ex-situ approach.

Extended Data Fig. 5 NMR investigation.

a, Tested reactions between MoS2 and thiolated molecules under exam (TP and BDT). Related NMR spectra at different time intervals for b, control experiment (BDT without MoS2), c, MoS2 + BDT and d, MoS2 + TP.

Extended Data Fig. 6 Mechanical test.

a, Experimental setup. b, Sketch of the samples subjected to bending deformation. c, Variation of the relative channel resistance ΔR/R0 of bare IDEs, MoS2 films, and MoS2 networks upon 5k and 10k bending cycles, along with related d, optical images of MoS2 films and networks before (left) and after (right) mechanical deformation.

Extended Data Fig. 7 Influence of the linker structure on electrical performance of MoS2 networks.

Transfer curves for MoS2 LG-TFTs a, before and after treatment with BDT linkers and b, before and after treatment with PDT linkers. All curves are recorded at Vds = -100 mV, using EMI-TFSI as electrolyte and a Pt wire as gate electrode. The molecular structures of BDT and PDT are also indicated.

Extended Data Fig. 8 Thermally-activated current response.

Ln I vs. 1000/T for VGback = + 80 V in a, MoS2 films b, TP-functionalized samples and c, MoS2 networks. EA is calculated from the curve slope with errors associated to different applied bias on the IDEs (from 1-2.5 V, that is, E = 4 x 105 – 1 x 106 V/m).

Supplementary information

Supplementary Information

Supplementary Figs. 1–30, discussion and Tables 1–7.

Source data

Source Data Fig. 2

Source data for the XPS (Fig. 2a) and Raman (Fig. 2b) of MoS2 films and networks.

Source Data Fig. 3

Source data for the electrical characterization of MoS2 films and networks reported in Fig. 3b and Fig. 3c.

Source Data Fig. 4

Source data for the temperature-dependent electrical characteristics of MoS2 films and networks reported in Fig. 4.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Ippolito, S., Kelly, A.G., Furlan de Oliveira, R. et al. Covalently interconnected transition metal dichalcogenide networks via defect engineering for high-performance electronic devices. Nat. Nanotechnol. 16, 592–598 (2021).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


Quick links

Find nanotechnology articles, nanomaterial data and patents all in one place. Visit Nano by Nature Research