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.

High-efficiency quantum-dot light-emitting devices with enhanced charge injection

Nature Photonics volume 7, pages 407–412 (2013)Cite this article

Subjects

Abstract

We report a colour-saturated, red quantum-dot light-emitting device (QLED) using an inverted organic–inorganic hybrid device structure and colloidal CdSe–CdS (core–shell) quantum-dot emitters. The strong electronic coupling of quantum dots to an adjacent layer of ZnO nanocrystals (which form the electron transport layer) facilitates charge transfer, which is responsible for both injecting electrons and maintaining an optimal charge balance for the quantum dot emitters. We show that QLED performance can be modified by controlling the distance of the electroluminescence recombination zone within the quantum dot film from the quantum dot–ZnO interface. Devices are reported with a luminous efficiency of 19 cd A−1, corresponding to an external quantum efficiency of 18% (which is close to the theoretical maximum of 20%) and an internal quantum efficiency of 90%. The corresponding luminous power efficiency exceeds 25 lm W−1 due to the low operating voltage of the device.

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

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Learn more

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

Figure 1: Energy diagram and emission spectrum of high-efficiency QLEDs.
Figure 2: Luminous power efficiency, current–voltage behaviour and EQE measurements of QLEDs.
Figure 3: Luminance and current efficiency performance of QLEDs.
Figure 4: Simultaneous measurements of electroluminescence and photoluminescence as a function of time.
Figure 5: Kelvin probe measurement of the evolution of surface potential over time.

Similar content being viewed by others

References

  1. Coe, S., Woo, W-K., Bawendi, M. & Bulovic, V. Electroluminescence from single monolayers of nanocrystals in molecular organic devices. Nature 420, 800–803 (2002).

    Article  ADS  Google Scholar 

  2. Caruge, J. M., Halpert, J. E., Wood, V., Bulovic, V. & Bawendi, M. G. Colloidal quantum-dot light-emitting diodes with metal-oxide charge transport layers. Nature Photon. 2, 247–250 (2008).

    Article  Google Scholar 

  3. Kim, T-H. et al. Full-colour quantum dot displays fabricated by transfer printing. Nature Photon. 5, 176–182 (2011).

    Article  ADS  Google Scholar 

  4. Qian, L., Zheng, Y., Xue, J. & Holloway, P. H. Stable and efficient quantum-dot light-emitting diodes based on solution-processed multilayer structures. Nature Photon. 5, 543–548 (2011).

    Article  ADS  Google Scholar 

  5. Adachi, C., Baldo, M. A., Thompson, M. E. & Forrest, S. R. Nearly 100% internal phosphorescence efficiency in an organic light-emitting device. J. Appl. Phys. 90, 5048–5051 (2001).

    Article  ADS  Google Scholar 

  6. Baldo, M. A. et al. Highly efficient phosphorescent emission from organic electroluminescent devices. Nature 395, 151–154 (1998).

    Article  ADS  Google Scholar 

  7. Anikeeva, P. O. et al. Photoluminescence of CdSe/ZnS core/shell quantum dots enhanced by energy transfer from a phosphorescent donor. Chem. Phys. Lett. 424, 120–125 (2006).

    Article  ADS  Google Scholar 

  8. Mashford, B. S., Nguyen, T-L., Wilson, G. J. & Mulvaney, P. All-inorganic quantum-dot light-emitting devices formed via low-cost, wet-chemical processing. J. Mater. Chem. 20, 167–172 (2010).

    Article  Google Scholar 

  9. Qian, L. et al. Electroluminescence from light-emitting polymer/ZnO nanoparticle heterojunctions at sub-bandgap voltages. Nano Today 5, 384–389 (2010).

    Article  Google Scholar 

  10. Kagan, C. R., Murray, C. B. & Bawendi, M. G. Long-range resonance transfer of electronic excitations in close-packed CdSe quantum-dot solids. Phys. Rev. B 54, 8633–8643 (1996).

    Article  ADS  Google Scholar 

  11. Caruge, J-M., Halpert, J. E., Bulović, V. & Bawendi, M. G. NiO as an inorganic hole-transporting layer in quantum-dot light-emitting devices. Nano Lett. 6, 2991–2994 (2006).

    Article  ADS  Google Scholar 

  12. Cho, K-S. et al. High-performance crosslinked colloidal quantum-dot light-emitting diodes. Nature Photon. 3, 341–345 (2009).

    Article  ADS  Google Scholar 

  13. Jha, P. P. & Guyot-Sionnest, P. Photoluminescence switching of charged quantum dot films. J. Phys. Chem. C 111, 15440–15445 (2007).

    Article  Google Scholar 

  14. Woo, W-K. et al. Reversible charging of CdSe nanocrystals in a simple solid-state device. Adv. Mater. 14, 1068–1071 (2002).

    Article  Google Scholar 

  15. Wang, X. et al. Non-blinking semiconductor nanocrystals. Nature 459, 686–689 (2009).

    Article  ADS  Google Scholar 

  16. Mahler, B. et al. Towards non-blinking colloidal quantum dots. Nature Mater. 7, 659–664 (2008).

    Article  ADS  Google Scholar 

  17. Li, S., Steigerwald, M. L. & Brus, L. E. Surface states in the photoionization of high-quality CdSe core/shell nanocrystals. ACS Nano 3, 1267–1273 (2009).

    Article  Google Scholar 

  18. Cherniavskaya, O., Chen, L., Islam, M. A. & Brus, L. Photoionization of individual CdSe/CdS core/shell nanocrystals on silicon with 2-nm oxide depends on surface band bending. Nano Lett. 3, 497–501 (2003).

    Article  ADS  Google Scholar 

  19. Jin, S., Song, N. & Lian, T. Suppressed blinking dynamics of single QDs on ITO. ACS Nano 4, 1545–1552 (2010).

    Article  Google Scholar 

  20. Wu, X. & Yeow, E. K. L. Charge-transfer processes in single CdSe/ZnS quantum dots with p-type NiO nanoparticles. Chem. Commun. 46, 4390–4392 (2010).

    Article  Google Scholar 

  21. Wood, V. et al. Selection of metal oxide charge transport layers for colloidal quantum dot LEDs. ACS Nano 3, 3581–3586 (2009).

    Article  Google Scholar 

  22. Inamdar, S. N., Ingole, P. P. & Haram, S. K. Determination of band structure parameters and the quasi-particle gap of CdSe quantum dots by cyclic voltammetry. ChemPhysChem 9, 2574–2579 (2008).

    Article  Google Scholar 

  23. Jasieniak, J., Califano, M. & Watkins, S. E. Size-dependent valence and conduction band-edge energies of semiconductor nanocrystals. ACS Nano 5, 5888–5902 (2011).

    Article  Google Scholar 

  24. Lee, H-D. et al. High efficiency tandem organic light-emitting diodes using interconnecting layer. Jpn J. Appl. Phys. 48, 082101 (2009).

    Article  ADS  Google Scholar 

  25. Li, D. et al. Different origins of visible luminescence in ZnO nanostructures fabricated by the chemical and evaporation methods. Appl. Phys. Lett. 85, 1601–1603 (2004).

    Article  ADS  Google Scholar 

  26. Tay, Y. Y., Tan, T. T., Liang, M. H., Boey, F. & Li, S. Specific defects, surface band bending and characteristic green emissions of ZnO. Phys. Chem. Chem. Phys. 12, 6008–6013 (2010).

    Article  Google Scholar 

  27. Van Dijken, A., Meulenkamp, E. A., Vanmaekelbergh, D. & Meijerink, A. Influence of adsorbed oxygen on the emission properties of nanocrystalline ZnO particles. J. Phys. Chem. B 104, 4355–4360 (2000).

    Article  Google Scholar 

  28. Lai, J. H., Su, S. H., Chen, H-H., Huang, J. C. A. & Wu, C-L. Stabilization of ZnO polar plane with charged surface nanodefects. Phys. Rev. B 82, 155406 (2010).

    Article  ADS  Google Scholar 

  29. Allen, M. W. et al. Bulk transport measurements in ZnO: the effect of surface electron layers. Phys. Rev. B 81, 075211 (2010).

    Article  ADS  Google Scholar 

  30. Tvrdy, K., Frantsuzov, P. A. & Kamat, P. V. Photoinduced electron transfer from semiconductor quantum dots to metal oxide nanoparticles. Proc. Natl Acad. Sci. USA 108, 29–34 (2011).

    Article  ADS  Google Scholar 

  31. Carlson, B., Leschkies, K., Aydil, E. S. & Zhu, X-Y. Valence band alignment at cadmium selenide quantum dot and zinc oxide (10110) interfaces. J. Phys. Chem. C 112, 8419–8423 (2008).

    Article  Google Scholar 

  32. Forrest, S. R., Bradley, D. D. C. & Thompson, M. E. Measuring the efficiency of organic light-emitting devices. Adv. Mater. 15, 1043–1048 (2003).

    Article  Google Scholar 

Download references

Acknowledgements

The authors would like to thank W. Tisdale (MIT) for collecting the transient photoluminescence data.

Author information

Authors and Affiliations

  1. QD Vision Incorporated, Lexington, 02421, Massachusetts, USA

    Benjamin S. Mashford, Matthew Stevenson, Zoran Popovic, Charles Hamilton, Zhaoqun Zhou, Craig Breen, Jonathan Steckel, Seth Coe-Sullivan & Peter T. Kazlas

  2. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, 02139, Massachusetts, USA

    Vladimir Bulovic

  3. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, 02139, Massachusetts, USA

    Moungi Bawendi

Authors
  1. Benjamin S. Mashford
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Matthew Stevenson
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Zoran Popovic
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Charles Hamilton
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Zhaoqun Zhou
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Craig Breen
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Jonathan Steckel
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Vladimir Bulovic
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Moungi Bawendi
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Seth Coe-Sullivan
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Peter T. Kazlas
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

B.S.M. and P.T.K. conceived the device and study design. B.S.M., M.S., Z.P. and Z.Z. fabricated and characterized devices. C.H. synthesized the quantum dots. P.T.K. supervised the study. All authors contributed to the analysis and interpretation of results and writing the paper.

Corresponding author

Correspondence to Peter T. Kazlas.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 201 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Mashford, B., Stevenson, M., Popovic, Z. et al. High-efficiency quantum-dot light-emitting devices with enhanced charge injection. Nature Photon 7, 407–412 (2013). https://doi.org/10.1038/nphoton.2013.70

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nphoton.2013.70

This article is cited by

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