Electric-field-driven dual-functional molecular switches in tunnel junctions

Abstract

To avoid crosstalk and suppress leakage currents in resistive random access memories (RRAMs), a resistive switch and a current rectifier (diode) are usually combined in series in a one diode–one resistor (1D–1R) RRAM. However, this complicates the design of next-generation RRAM, increases the footprint of devices and increases the operating voltage as the potential drops over two consecutive junctions1. Here, we report a molecular tunnel junction based on molecules that provide an unprecedented dual functionality of diode and variable resistor, resulting in a molecular-scale 1D–1R RRAM with a current rectification ratio of 2.5 × 104 and resistive on/off ratio of 6.7 × 103, and a low drive voltage of 0.89 V. The switching relies on dimerization of redox units, resulting in hybridization of molecular orbitals accompanied by directional ion migration. This electric-field-driven molecular switch operating in the tunnelling regime enables a class of molecular devices where multiple electronic functions are preprogrammed inside a single molecular layer with a thickness of only 2 nm.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Schematic illustrations of the junctions and dimerization.
Fig. 2: Electrical properties of the junctions.
Fig. 3: Operating mechanism of the junctions.

Data availability

The data used in Figs. 13, Extended Data Figs. 14 and in the Supplementary Information are available from the Harvard Dataverse (https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/QUVXXY).

Code availability

The source code used to analyse the raw data from the junctions is available from Harvard Dataverse (https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/QUVXXY).

References

  1. 1.

    Cho, B., Song, S., Ji, Y., Kim, T. W. & Lee, T. Organic resistive memory devices: performance enhancement, integration and advanced architectures. Adv. Funct. Mater. 21, 2806–2829 (2011).

    CAS  Article  Google Scholar 

  2. 2.

    Jeong, H., Kim, D., Xiang, D. & Lee, T. High-yield functional molecular electronic devices. ACS Nano. 11, 6511–6548 (2017).

    CAS  Article  Google Scholar 

  3. 3.

    Fuller, E. J. et al. Parallel programming of an ionic floating-gate memory array for scalable neuromorphic computing. Science 364, 570–574 (2019).

    CAS  Article  Google Scholar 

  4. 4.

    Byun, J. et al. Electronic skins for soft, compact, reversible assembly of wirelessly activated fully soft robots. Sci. Robot. 3, eaas9020 (2018).

    Article  Google Scholar 

  5. 5.

    Kumar, S. et al. Chemical locking in molecular tunneling junctions enables nonvolatile memory with large on–off ratios. Adv. Mater. 31, 1807831 (2019).

    Article  CAS  Google Scholar 

  6. 6.

    van der Molen, S. J. et al. Light-controlled conductance switching of ordered metal–molecule–metal devices. Nano Lett. 9, 76–80 (2009).

    Article  CAS  Google Scholar 

  7. 7.

    Lee, J., Chang, H., Kim, S., Bang, G. S. & Lee, H. Molecular monolayer nonvolatile memory with tunable molecules. Angew. Chem. Int. Ed. 48, 8501–8504 (2009).

    CAS  Article  Google Scholar 

  8. 8.

    Schwarz, F. et al. Field-induced conductance switching by charge-state alternation in organometallic single-molecule junctions. Nat. Nanotechnol. 11, 170–176 (2015).

    Article  CAS  Google Scholar 

  9. 9.

    Lörtscher, E., Ciszek, J. W., Tour, J. & Riel, H. Reversible and controllable switching of a single-molecule junction. Small 2, 973–977 (2006).

    Article  CAS  Google Scholar 

  10. 10.

    Aragonès, A. C. et al. Large conductance switching in a single-molecule device through room temperature spin-dependent transport. Nano Lett. 16, 218–226 (2016).

    Article  CAS  Google Scholar 

  11. 11.

    Bogani, L. & Wernsdorfer, W. Molecular spintronics using single-molecule magnets. Nat. Mater. 7, 179–186 (2008).

    CAS  Article  Google Scholar 

  12. 12.

    Russew, M. M. & Hecht, S. Photoswitches: from molecules to materials. Adv. Mater. 22, 3348–3360 (2010).

    CAS  Article  Google Scholar 

  13. 13.

    Simão, C. et al. A robust molecular platform for non-volatile memory devices with optical and magnetic responses. Nat. Chem. 3, 359–364 (2011).

    Article  CAS  Google Scholar 

  14. 14.

    Erbas-Cakmak, S., Leigh, D. A., McTernan, C. T. & Nussbaumer, A. L. Artificial molecular machines. Chem. Rev. 115, 10081–10206 (2015).

    CAS  Article  Google Scholar 

  15. 15.

    de Ruiter, G. & van der Boom, M. E. Sequential logic and random access memory (RAM): a molecular approach. J. Mater. Chem. 21, 17575–17581 (2011).

    Article  CAS  Google Scholar 

  16. 16.

    Jia, C. et al. Covalently bonded single-molecule junctions with stable and reversible photoswitched conductivity. Science 352, 1443–1445 (2016).

    CAS  Article  Google Scholar 

  17. 17.

    Liu, B., Blaszczyk, A., Mayor, M. & Wandlowski, T. Redox-switching in a viologen-type adlayer: an electrochemical shell-isolated nanoparticle enhanced Raman spectroscopy study on Au(111)-(1 × 1) single crystal electrodes. ACS Nano. 5, 5662–5672 (2011).

    CAS  Article  Google Scholar 

  18. 18.

    Zhang, D. W., Tian, J., Chen, L., Zhang, L. & Li, Z. T. Dimerization of conjugated radical cations: an emerging non-covalent interaction for self-assembly. Chem. Asian J. 10, 56–68 (2015).

    CAS  Article  Google Scholar 

  19. 19.

    Tang, X., Schneider, T. W., Walker, J. W. & Buttry, D. A. Dimerized π-complexes in self-assembled monolayers containing viologens: an origin of unusual wave shapes in the voltammetry of monolayers. Langmuir 12, 5921–5933 (1996).

    CAS  Article  Google Scholar 

  20. 20.

    Chen, X. et al. Molecular diodes with rectification ratios exceeding 105 driven by electrostatic interactions. Nat. Nanotechnol. 12, 797–803 (2017).

    CAS  Article  Google Scholar 

  21. 21.

    Nijhuis, C. A., Reus, W. F. & Whitesides, G. M. Molecular rectification in metal–SAM–metal oxide–metal junctions. J. Am. Chem. Soc. 131, 17814–17827 (2009).

    CAS  Article  Google Scholar 

  22. 22.

    Bergren, A. J., McCreery, R. L., Stoyanov, S. R., Gusarov, S. & Kovalenko, A. Electronic characteristics and charge transport mechanisms for large area aromatic molecular junctions. J. Phys. Chem. C 114, 15806–15815 (2010).

    CAS  Article  Google Scholar 

  23. 23.

    Wimbush, K. S. et al. Bias induced transition from an ohmic to a non-ohmic interface in supramolecular tunneling junctions with Ga2O3/EGaIn top electrodes. Nanoscale 6, 11246–11258 (2014).

    CAS  Article  Google Scholar 

  24. 24.

    Sangeeth, C. S. S., Wan, A. & Nijhuis, C. A. Equivalent circuits of a self-assembled monolayer-based tunnel junction determined by impedance spectroscopy. J. Am. Chem. Soc. 136, 11134–11144 (2014).

    CAS  Article  Google Scholar 

  25. 25.

    Lindsey, J. S. & Bocian, D. F. Molecules for charge-based information storage. Acc. Chem. Res. 44, 638–650 (2011).

    CAS  Article  Google Scholar 

  26. 26.

    Kumar, R., Pillai, R. G., Pekas, N., Wu, Y. & McCreery, R. L. Spatially resolved Raman spectroelectrochemistry of solid-state polythiophene/viologen memory devices. J. Am. Chem. Soc. 134, 14869–14876 (2012).

    CAS  Article  Google Scholar 

  27. 27.

    Wu, J., Mobley, K. & McCreery, R. L. Electronic characteristics of fluorene/TiO2 molecular heterojunctions. J. Chem. Phys. 126, 024704 (2007).

    Article  CAS  Google Scholar 

  28. 28.

    Chandra Mondal, P., Tefashe, U. M. & McCreery, R. L. Internal electric field modulation in molecular electronic devices by atmosphere and mobile ions. J. Am. Chem. Soc. 140, 7239–7247 (2018).

    CAS  Article  Google Scholar 

  29. 29.

    Atesci, H. et al. Humidity-controlled rectification switching in ruthenium-complex molecular junctions. Nat. Nanotechnol. 13, 117–121 (2018).

    CAS  Article  Google Scholar 

  30. 30.

    Bonifas, A. P. & McCreery, R. L. Solid state spectroelectrochemistry of redox reactions in polypyrrole/oxide molecular heterojunctions. Anal. Chem. 84, 2459–2465 (2012).

    CAS  Article  Google Scholar 

  31. 31.

    Trasobares, J., Vuillaume, D., Théron, D. & Clément, N. A 17 GHz molecular rectifier. Nat. Commun. 7, 12850 (2016).

    CAS  Article  Google Scholar 

  32. 32.

    Jortner, J., Nitzan, A. & Ratner, M. A. in Introducing Molecular Electronics (eds Cuniberti, G., Richter, K. & Fagas, G.) 13–54 (Springer, 2005).

  33. 33.

    Brinks, D. et al. Ultrafast dynamics of single molecules. Chem. Soc. Rev. 43, 2476–2491 (2014).

    CAS  Article  Google Scholar 

  34. 34.

    Nerngchamnong, N. et al. The role of van der Waals forces in the performance of molecular diodes. Nat. Nanotechnol. 8, 113–118 (2013).

    CAS  Article  Google Scholar 

  35. 35.

    Frisch, M. J. et al. Gaussian 16 Revision A 03 (Gaussian, 2016).

  36. 36.

    Grimme, S. Semiempirical GGA-type density functional constructed with a long-range dispersion correction. J. Comput. Chem. 27, 1787–1799 (2006).

    CAS  Article  Google Scholar 

  37. 37.

    Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15–50 (1996).

    CAS  Article  Google Scholar 

  38. 38.

    Grimme, S., Ehrlich, S. & Goerigk, L. Effect of the damping function in dispersion corrected density functional theory. J. Comput. Chem. 32, 1456–1465 (2011).

    CAS  Article  Google Scholar 

  39. 39.

    Reus, W. F. et al. Statistical tools for analyzing measurements of charge transport. J. Phys. Chem. C 116, 6714–6733 (2012).

    CAS  Article  Google Scholar 

  40. 40.

    Wan, A., Jiang, L., Sangeeth, C. S. S. & Nijhuis, C. A. Reversible soft top-contacts to yield molecular junctions with precise and reproducible electrical characteristics. Adv. Funct. Mater. 24, 4442–4456 (2014).

    CAS  Article  Google Scholar 

  41. 41.

    Wan, A. et al. Arrays of high quality SAM-based junctions and their application in molecular diode based logic. Nanoscale 7, 19547–19556 (2015).

    CAS  Article  Google Scholar 

  42. 42.

    Lin, Y. et al. Vacuum filling of complex microchannels with liquid metal. Lab Chip 17, 3043–3050 (2017).

    CAS  Article  Google Scholar 

  43. 43.

    Nijhuis, C. A., Reus, W. F., Siegel, A. C. & Whitesides, G. M. A molecular half-wave rectifier. J. Am. Chem. Soc. 133, 15397–15411 (2011).

    CAS  Article  Google Scholar 

  44. 44.

    Geraskina, M. R., Dutton, A. S., Juetten, M. J., Wood, S. A. & Winter, A. H. The viologen cation radical pimer: a case of dispersion-driven bonding. Angew. Chem. Int. Ed. 56, 9435–9439 (2017).

    CAS  Article  Google Scholar 

  45. 45.

    Yuan, L., Breuer, R., Jiang, L., Schmittel, M. & Nijhuis, C. A. A molecular diode with a statistically robust rectification ratio of three orders of magnitude. Nano Lett. 15, 5506–5512 (2015).

    CAS  Article  Google Scholar 

  46. 46.

    Du, W. et al. Directional excitation of surface plasmon polaritons via molecular through-bond tunneling across double-barrier tunnel junctions. Nano Lett. 19, 4634–4640 (2019).

    CAS  Article  Google Scholar 

  47. 47.

    Gann, E., McNeill, C. R., Tadich, A., Cowie, B. C. C. & Thomsen, L. Quick AS NEXAFS Tool (QANT): a program for NEXAFS loading and analysis developed at the Australian Synchrotron. J. Synchrotron Rad. 23, 374–380 (2016).

    CAS  Article  Google Scholar 

  48. 48.

    Stöhr, J. NEXAFS Spectroscopy (Series in Surface Sciences, Springer, 1992).

  49. 49.

    Vilan, A. Revealing tunnelling details by normalized differential conductance analysis of transport across molecular junctions. Phys. Chem. Chem. Phys. 19, 27166–27172 (2017).

    CAS  Article  Google Scholar 

  50. 50.

    Garrigues, A. R. et al. Temperature dependent charge transport across tunnel junctions of single-molecules and self-assembled monolayers: a comparative study. Dalton Trans. 45, 17153–17159 (2016).

    CAS  Article  Google Scholar 

  51. 51.

    Garrigues, A. R., Wang, L., del Barco, E. & Nijhuis, C. A. Electrostatic control over temperature-dependent tunnelling across a single-molecule junction. Nat. Commun. 7, 11595 (2016).

    CAS  Article  Google Scholar 

  52. 52.

    Sierra, M. A. et al. How to distinguish between interacting and noninteracting molecules in tunnel junctions. Nanoscale 10, 3904–3910 (2018).

    CAS  Article  Google Scholar 

  53. 53.

    Yuan, L. et al. Controlling the direction of rectification in a molecular diode. Nat. Commun. 6, 6324 (2015).

    CAS  Article  Google Scholar 

  54. 54.

    Yuan, L. et al. Transition from direct to inverted charge transport Marcus regions in molecular junctions via molecular orbital gating. Nat. Nanotechnol. 13, 322–329 (2018).

    CAS  Article  Google Scholar 

Download references

Acknowledgements

We thank the Ministry of Education for supporting this research (award no. MOE2018-T2-1-088), the Prime Minister’s Office, Singapore, under its Medium Sized Centre programme, Science Foundation Ireland (SFI) under awards 15/CDA/3491 and 12/RC/2275 (SSPC), the SFI/Higher Education Authority Irish Center for High-End Computing (ICHEC) for computing resources, the US National Science Foundation (grant no. ECCS#1916874) and the Australian Research Council (grant no. FT160100207). We thank W. Ze for preparing the moulds for the microfluidic PDMS top electrodes, T. Salin for assistance with UPS and XPS measurements, V. Kalathingal for writing the LabView program for endurance measurements and A. Tadich for AR-XPS and NEXAFS measurements conducted at the Australian Synchrotron (under ANSTO).

Author information

Affiliations

Authors

Contributions

C.A.N. conceived and supervised the project. D.T. conducted all the DFT calculations. E.d.B. and C.N. conducted all the analytical modelling. Y.H. synthesized the compounds and performed the CV, electrical and UV–vis measurements. Z.Z. performed the AR-XPS and NEXAFS measurements and analysed the data with the assistance of D.Q. H.P.A.G.A. and Y.H. performed the switching speed and frequency measurements and H.P.A.G.A. conducted the analysis of all the data. T.J.D. developed the MATLAB code for electrical data analysis. C.A.N. and D.T. wrote the manuscript and all authors commented on it.

Corresponding authors

Correspondence to Enrique del Barco or Damien Thompson or Christian A. Nijhuis.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

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

Extended data

Extended Data Fig. 1 Electrical properties of the junctions.

Heat maps of the log10|J| vs. V (a, b, c and d) and log10(R2/1) vs. V (e, f, g and h) for Ag-S(CH2)11MV2+X-2//GaOx/EGaIn junctions [X- = ClO4- (a, e) and PF6-(b, f)] and Ag-S(CH2)11X//GaOX/EGaIn junctions [X=NH3+Cl- (c, g) and COO-Na+ (d, h)]. Black solid lines are the Gaussian log-averages.

Extended Data Fig. 2 Retention time and endurance measurements.

Current retention of the on and off state of Ag-S(CH2)11MV2+I-2//GaOx/EGaIn junctions (a and b). Read-write-read-erase pulse sequence for Ag-S(CH2)11MV2+X-2//GaOx/EGaIn junction with X=Cl-(c, VW = -1.2 V, VE = +1.2 V, Vr = -0.3 V) and X=I- (e, VW = -1 V, VE = +1 V, Vr = -0.3 V). The corresponding output where red data points indicate R1, blue indicate R2, black indicate W and gray indicate E for junction with X=Cl- (d) and X=I- (f).

Extended Data Fig. 3 Representative J(V) curves.

Individual J(V) curves for Ag-S(CH2)11MV2+X-2//GaOx/EGaIn junctions with X-= I- (a), Br- (b), Cl- (c) and F- (d).

Extended Data Fig. 4 Operating mechanisms.

Experimentally determined maximum R2/1 for Ag-S(CH2)11MV2+X-2//GaOx/EGaIn junctions (X- = I-, Br-, Cl-, F-, ClO4- and PF6-) as a function of the DFT-calculated stability of dimer in on state vs. off state (Δdimer) over experimentally determined energy offset between HOMO and electrode Fermi level (δEHOMO). The error bars represent the 95% confidence intervals. The black dashed line is the linear fit for these six data points with a coefficient of determination R2 = 0.99.

Supplementary information

Supplementary Information

Supplementary Figs. 1–31, Discussion sections 1–14 and Tables 1–6.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Han, Y., Nickle, C., Zhang, Z. et al. Electric-field-driven dual-functional molecular switches in tunnel junctions. Nat. Mater. (2020). https://doi.org/10.1038/s41563-020-0697-5

Download citation