Skip to main content

Thank you for visiting nature.com. 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.

  • Article
  • Published:

Upconversion electroluminescence in 2D semiconductors integrated with plasmonic tunnel junctions

Nature Nanotechnology (2024)Cite this article

Subjects

Abstract

Plasmonic tunnel junctions are a unique electroluminescent system in which light emission occurs via an interplay between tunnelling electrons and plasmonic fields instead of electron–hole recombination as in conventional light-emitting diodes. It was previously shown that placing luminescent molecules in the tunneling pathway of nanoscopic tunnel junctions results in peculiar upconversion electroluminescence where the energy of emitted photons exceeds that of excitation electrons. Here we report the observation of upconversion electroluminescence in macroscopic van der Waals plasmonic tunnel junctions comprising gold and few-layer graphene electrodes separated by a ~2-nm-thick hexagonal boron nitride tunnel barrier and a monolayer semiconductor. We find that the semiconductor ground exciton emission is triggered at excitation electron energies lower than the semiconductor optical gap. Interestingly, this upconversion is reached in devices operating at a low conductance (<10−6 S) and low power density regime (<102 W cm−2), defying explanation through existing proposed mechanisms. By examining the scaling relationship between plasmonic and excitonic emission intensities, we elucidate the role of inelastic electron tunnelling dipoles that induce optically forbidden transitions in the few-layer graphene electrode and ultrafast hot carrier transfer across the van der Waals interface.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Device schematic and bimodal electroluminescence.
Fig. 2: Bias-dependent bimodal emission characteristics.
Fig. 3: Momentum-indirect excitation of high energy carriers driven by IET dipoles.
Fig. 4: Formation mechanism of the upconverted excitons.

Similar content being viewed by others

Data availability

All data are available in the article and the Supplementary Information, and are available from the corresponding authors on reasonable request.

Code availability

The source code for the calculations conducted in this study is available from the corresponding authors on reasonable request.

References

  1. Lambe, J. & McCarthy, S. L. Light emission from inelastic electron tunneling. Phys. Rev. Lett. 37, 923–925 (1976).

    Article  CAS  Google Scholar 

  2. Du, W., Wang, T., Chu, H.-S. & Nijhuis, C. A. Highly efficient on-chip direct electronic–plasmonic transducers. Nat. Photon. 11, 623–627 (2017).

    Article  CAS  Google Scholar 

  3. Qian, H. et al. Efficient light generation from enhanced inelastic electron tunnelling. Nat. Photon. 12, 485–488 (2018).

    Article  CAS  Google Scholar 

  4. Parzefall, M. et al. Antenna-coupled photon emission from hexagonal boron nitride tunnel junctions. Nat. Nanotechnol. 10, 1058–1063 (2015).

    Article  CAS  PubMed  Google Scholar 

  5. Flaxer, E., Sneh, O. & Cheshnovsky, O. Molecular light emission induced by inelastic electron tunneling. Science 262, 2012–2014 (1993).

    Article  CAS  PubMed  Google Scholar 

  6. Wu, S., Nazin, G. & Ho, W. Intramolecular photon emission from a single molecule in a scanning tunneling microscope. Phys. Rev. B 77, 205430 (2008).

    Article  Google Scholar 

  7. Schuler, B. et al. Electrically driven photon emission from individual atomic defects in monolayer WS2. Sci. Adv. 6, eabb5988 (2020).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Lutz, T. et al. Molecular orbital gates for plasmon excitation. Nano Lett. 13, 2846–2850 (2013).

    Article  CAS  PubMed  Google Scholar 

  9. Doppagne, B. et al. Vibronic spectroscopy with submolecular resolution from STM-induced electroluminescence. Phys. Rev. Lett. 118, 127401 (2017).

    Article  PubMed  Google Scholar 

  10. Doppagne, B. et al. Electrofluorochromism at the single-molecule level. Science 361, 251–255 (2018).

    Article  CAS  PubMed  Google Scholar 

  11. Merino, P. et al. Bimodal exciton–plasmon light sources controlled by local charge carrier injection. Sci. Adv. 4, eaap8349 (2018).

    Article  PubMed  PubMed Central  Google Scholar 

  12. Merino, P., Große, C., Rosławska, A., Kuhnke, K. & Kern, K. Exciton dynamics of C60-based single-photon emitters explored by Hanbury Brown–Twiss scanning tunnelling microscopy. Nat. Commun. 6, 8461 (2015).

    Article  CAS  PubMed  Google Scholar 

  13. Kuhnke, K., Große, C., Merino, P. & Kern, K. Atomic-scale imaging and spectroscopy of electroluminescence at molecular interfaces. Chem. Rev. 117, 5174–5222 (2017).

    Article  CAS  PubMed  Google Scholar 

  14. Gutzler, R., Garg, M., Ast, C. R., Kuhnke, K. & Kern, K. Light–matter interaction at atomic scales. Nat. Rev. Phys. 3, 441–453 (2021).

    Article  Google Scholar 

  15. Dong, Z. C. et al. Generation of molecular hot electroluminescence by resonant nanocavity plasmons. Nat. Photon. 4, 50–54 (2010).

    Article  CAS  Google Scholar 

  16. Chen, G. et al. Spin-triplet-mediated up-conversion and crossover behavior in single-molecule electroluminescence. Phys. Rev. Lett. 122, 177401 (2019).

    Article  CAS  PubMed  Google Scholar 

  17. Schull, G., Néel, N., Johansson, P. & Berndt, R. Electron–plasmon and electron–electron interactions at a single atom contact. Phys. Rev. Lett. 102, 057401 (2009).

    Article  PubMed  Google Scholar 

  18. Peters, P.-J. et al. Quantum coherent multielectron processes in an atomic scale contact. Phys. Rev. Lett. 119, 066803 (2017).

    Article  PubMed  Google Scholar 

  19. Schneider, N. L., Schull, G. & Berndt, R. Optical probe of quantum shot-noise reduction at a single-atom contact. Phys. Rev. Lett. 105, 026601 (2010).

    Article  PubMed  Google Scholar 

  20. Kalathingal, V., Dawson, P. & Mitra, J. Scanning tunnelling microscope light emission: finite temperature current noise and over cut-off emission. Sci. Rep. 7, 1–10 (2017).

    Article  CAS  Google Scholar 

  21. Buret, M. et al. Spontaneous hot-electron light emission from electron-fed optical antennas. Nano Lett. 15, 5811–5818 (2015).

    Article  CAS  PubMed  Google Scholar 

  22. Parzefall, M. et al. Light from van der Waals quantum tunneling devices. Nat. Commun. 10, 292 (2019).

    Article  PubMed  PubMed Central  Google Scholar 

  23. Sun, J. et al. Light-emitting plexciton: exploiting plasmon–exciton interaction in the intermediate coupling regime. ACS Nano 12, 10393–10402 (2018).

    Article  CAS  PubMed  Google Scholar 

  24. Péchou, R. et al. Plasmonic-induced luminescence of MoSe2 monolayers in a scanning tunneling microscope. ACS Photon. 7, 3061–3070 (2020).

    Article  Google Scholar 

  25. Qi, P. et al. Giant excitonic upconverted emission from two-dimensional semiconductor in doubly resonant plasmonic nanocavity. Light. Sci. Appl. 11, 176 (2022).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  26. Froehlicher, G., Lorchat, E. & Berciaud, S. Charge versus energy transfer in atomically thin graphene-transition metal dichalcogenide van der Waals heterostructures. Phys. Rev. 8, 011007 (2018).

    Article  CAS  Google Scholar 

  27. Jeong, T. Y. et al. Spectroscopic studies of atomic defects and bandgap renormalization in semiconducting monolayer transition metal dichalcogenides. Nat. Commun. 10, 3825 (2019).

    Article  PubMed  PubMed Central  Google Scholar 

  28. Wang, Z., Kalathingal, V., Hoang, T. X., Chu, H.-S. & Nijhuis, C. A. Optical anisotropy in van der Waals materials: impact on direct excitation of plasmons and photons by quantum tunneling. Light. Sci. Appl. 10, 230 (2021).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  29. Lieb, M. A., Zavislan, J. M. & Novotny, L. Single-molecule orientations determined by direct emission pattern imaging. J. Opt. Soc. Am. B 21, 1210–1215 (2004).

    Article  CAS  Google Scholar 

  30. Román, R. J. P. et al. Electroluminescence of monolayer WS2 in a scanning tunneling microscope: effect of bias polarity on spectral and angular distribution of emitted light. Phys. Rev. B 106, 085419 (2022).

    Article  Google Scholar 

  31. Schuller, J. A. et al. Orientation of luminescent excitons in layered nanomaterials. Nat. Nanotechnol. 8, 271–276 (2013).

    Article  CAS  PubMed  Google Scholar 

  32. Wang, J., Verzhbitskiy, I. & Eda, G. Electroluminescent devices based on 2D semiconducting transition metal dichalcogenides. Adv. Mater. 30, 1802687 (2018).

    Article  Google Scholar 

  33. Dobusch, L., Schuler, S., Perebeinos, V. & Mueller, T. Thermal light emission from monolayer MoS2. Adv. Mater. 29, 1701304 (2017).

    Article  Google Scholar 

  34. Zhou, Y. et al. Probing dark excitons in atomically thin semiconductors via near-field coupling to surface plasmon polaritons. Nat. Nanotechnol. 12, 856–860 (2017).

    Article  CAS  PubMed  Google Scholar 

  35. Wang, S. et al. Efficient carrier-to-exciton conversion in field emission tunnel diodes based on MIS-type van der Waals heterostack. Nano Lett. 17, 5156–5162 (2017).

    Article  CAS  PubMed  Google Scholar 

  36. Tielrooij, K. et al. Electrical control of optical emitter relaxation pathways enabled by graphene. Nat. Phys. 11, 281–287 (2015).

    Article  CAS  Google Scholar 

  37. Federspiel, F. et al. Distance dependence of the energy transfer rate from a single semiconductor nanostructure to graphene. Nano Lett. 15, 1252–1258 (2015).

    Article  CAS  PubMed  Google Scholar 

  38. Koppens, F. H., Chang, D. E. & García de Abajo, F. J. Graphene plasmonics: a platform for strong light–matter interactions. Nano Lett. 11, 3370–3377 (2011).

    Article  CAS  PubMed  Google Scholar 

  39. Gonçalves, P. A. D. et al. Plasmon–emitter interactions at the nanoscale. Nat. Commun. 11, 366 (2020).

    Article  PubMed  PubMed Central  Google Scholar 

  40. Yuan, L. et al. Photocarrier generation from interlayer charge-transfer transitions in WS2-graphene heterostructures. Sci. Adv. 4, e1700324 (2018).

    Article  PubMed  PubMed Central  Google Scholar 

  41. Chen, Y., Li, Y., Zhao, Y., Zhou, H. & Zhu, H. Highly efficient hot electron harvesting from graphene before electron–hole thermalization. Sci. Adv. 5, eaax9958 (2019).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  42. Swathi, R. & Sebastian, K. Long range resonance energy transfer from a dye molecule to graphene has (distance)−4 dependence. J. Chem. Phys. 130, 086101 (2009).

    Article  CAS  PubMed  Google Scholar 

  43. Gaudreau, L. et al. Universal distance-scaling of nonradiative energy transfer to graphene. Nano Lett. 13, 2030–2035 (2013).

    Article  CAS  PubMed  Google Scholar 

  44. Dias, E. J. et al. Probing nonlocal effects in metals with graphene plasmons. Phys. Rev. B 97, 245405 (2018).

    Article  CAS  Google Scholar 

  45. Linardy, E., Trushin, M., Watanabe, K., Taniguchi, T. & Eda, G. Electro‐optic upconversion in van der Waals heterostructures via nonequilibrium photocarrier tunneling. Adv. Mater. 32, 2001543 (2020).

    Article  CAS  Google Scholar 

  46. Brotons-Gisbert, M. et al. Out-of-plane orientation of luminescent excitons in two-dimensional indium selenide. Nat. Commun. 10, 3913 (2019).

    Article  PubMed  PubMed Central  Google Scholar 

Download references

Acknowledgements

We acknowledge the support from the Ministry of Education (MOE), Singapore, under Academic Research Fund (AcRF) Tier 3 (grant no. MOE2018-T3-1-005), and the National Research Foundation (NRF), under the Prime Minister’s Office, Singapore, under the Medium Sized Centre Programme and the Competitive Research Programme (CRP) (grant no. NRF-CRP17-2017-08). M.T. acknowledges Institute for Functional Intelligent Materials (I-FIM, grant no. EDUNC-33-18-279-V12). B.Ö. acknowledges the Singapore NRF Investigatorship (grant no. NRF-NRFI2018-8) and MOE-AcRF-Tier 2 (grant no. MOE-T2EP50220-0017). J.W. acknowledges the National Key R&D Program of China (grant no. 2021YFA1200804).

Author information

Author notes

  1. These authors contributed equally: Zhe Wang, Vijith Kalathingal.

Authors and Affiliations

  1. Department of Chemistry, National University of Singapore, Singapore, Singapore

    Zhe Wang & Goki Eda

  2. Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore

    Zhe Wang, Vijith Kalathingal & Yongxin Guo

  3. Department of Physics, Kannur University, Swami Anandatheertha Campus-Payyanur, Kannur, India

    Vijith Kalathingal

  4. Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore

    Maxim Trushin, Jiawei Liu & Barbaros Özyilmaz

  5. Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore

    Maxim Trushin, Jiawei Liu, Barbaros Özyilmaz & Goki Eda

  6. Department of Material Science and Engineering, National University of Singapore, Singapore, Singapore

    Maxim Trushin & Barbaros Özyilmaz

  7. Department of Physics, National University of Singapore, Singapore, Singapore

    Jiawei Liu, Barbaros Özyilmaz & Goki Eda

  8. CAS Key Laboratory of Nano-Bio Interface and Key Laboratory of Nanodevices and Applications, i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, China

    Junyong Wang

  9. Hybrid Materials for Opto-Electronics Group, Department of Molecules and Materials, MESA+ Institute for Nanotechnology, Molecules Center and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, Enschede, the Netherlands

    Christian A. Nijhuis

Authors
  1. Zhe Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Vijith Kalathingal
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Maxim Trushin
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Jiawei Liu
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Junyong Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Yongxin Guo
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Barbaros Özyilmaz
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Christian A. Nijhuis
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Goki Eda
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

G.E., Z.W. and V.K. conceived the project. Z.W. and J.L. fabricated the devices. Z.W. performed the measurements. Z.W. and V.K. analysed the experimental data. V.K., M.T. and Z.W. performed the theoretical analysis. G.E. and C.A.N. co-supervised the project. Z.W., V.K. and G.E. co-wrote the paper. G.E., C.A.N, Y.G. and B.Ö. provided equipment and laboratory facilities. All authors contributed to the scientific discussions and paper revisions.

Corresponding authors

Correspondence to Christian A. Nijhuis or Goki Eda.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Nanotechnology thanks the anonymous reviewers for their contribution to the peer review of this work.

Additional information

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

Supplementary information

Supplementary Information

Supplementary Figs. 1–14 and discussion.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Wang, Z., Kalathingal, V., Trushin, M. et al. Upconversion electroluminescence in 2D semiconductors integrated with plasmonic tunnel junctions. Nat. Nanotechnol. (2024). https://doi.org/10.1038/s41565-024-01650-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1038/s41565-024-01650-0

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing