Bright colloidal quantum dot light-emitting diodes enabled by efficient chlorination

Abstract

The external quantum efficiencies of state-of-the-art colloidal quantum dot light-emitting diodes (QLEDs) are now approaching the limit set by the out-coupling efficiency. However, the brightness of these devices is constrained by the use of poorly conducting emitting layers, a consequence of the present-day reliance on long-chain organic capping ligands. Here, we report how conductive and passivating halides can be implemented in Zn chalcogenide-shelled colloidal quantum dots to enable high-brightness green QLEDs. We use a surface management reagent, thionyl chloride (SOCl2), to chlorinate the carboxylic group of oleic acid and graft the surfaces of the colloidal quantum dots with passivating chloride anions. This results in devices with an improved mobility that retain high external quantum efficiencies in the high-injection-current region and also feature a reduced turn-on voltage of 2.5 V. The treated QLEDs operate with a brightness of 460,000 cd m−2, significantly exceeding that of all previously reported solution-processed LEDs.

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: Chlorination ligand exchange mechanism.
Fig. 2: Characterization of C–S–S–Cl CQDs.
Fig. 3: Conductivity and QLED architecture characterization.
Fig. 4: EQE characterization of QLED devices.
Fig. 5: Electroluminescence spectra under different biases.
Fig. 6: Optoelectronic simulations of charge carrier distributions and recombination rates inside the active layers.

References

  1. 1.

    Reineke, S. Complementary LED technologies. Nat. Mater. 14, 459–462 (2015).

    ADS  Article  Google Scholar 

  2. 2.

    Shirasaki, Y., Supran, G. J., Bawendi, M. G. & Bulović, V. Emergence of colloidal quantum-dot light-emitting technologies. Nat. Photon. 7, 13–23 (2013).

    ADS  Article  Google Scholar 

  3. 3.

    Colvin, V. L., Schlamp, M. C. & Alivisatos, A. P. Light-emitting-diodes made from cadmium selenide nanocrystals and a semiconducting polymer. Nature 370, 354–357 (1994).

    ADS  Article  Google Scholar 

  4. 4.

    Dai, X. et al. Solution-processed, high-performance light-emitting diodes based on quantum dots. Nature 515, 96–99 (2014).

    ADS  Article  Google Scholar 

  5. 5.

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

    ADS  Article  Google Scholar 

  6. 6.

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

    ADS  Article  Google Scholar 

  7. 7.

    Mashford, B. S. et al. High-efficiency quantum-dot light-emitting devices with enhanced charge injection. Nat. Photon. 7, 407–412 (2013).

    ADS  Article  Google Scholar 

  8. 8.

    Dai, X., Deng, Y., Peng, X. & Jin, Y. Quantum-dot light-emitting diodes for large-area displays: towards the dawn of commercialization. Adv. Mater. 29, 1607022 (2017).

    Article  Google Scholar 

  9. 9.

    Shen, H. et al. High-efficiency, low turn-on voltage blue-violet quantum-dot-based light-emitting diodes. Nano Lett. 15, 1211–1216 (2015).

    ADS  Article  Google Scholar 

  10. 10.

    Li, Z. et al. Efficient and long-life green light-emitting diodes comprising tridentate thiol capped quantum dots. Laser Photon. Rev. 11, 1600227 (2017).

    Article  Google Scholar 

  11. 11.

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

    ADS  Article  Google Scholar 

  12. 12.

    Yang, Y. et al. High-efficiency light-emitting devices based on quantum dots with tailored nanostructures. Nat. Photon. 9, 259–266 (2015).

    ADS  Article  Google Scholar 

  13. 13.

    Shirasaki, Y., Supran, G. J., Tisdale, W. A. & Bulović, V. Origin of efficiency roll-off in colloidal quantum-dot light-emitting diodes. Phys. Rev. Lett. 110, 217403 (2013).

    ADS  Article  Google Scholar 

  14. 14.

    Dolzhnikov, D. S. et al. Composition-matched molecular “solders” for semiconductors. Science 347, 425–428 (2015).

    ADS  Article  Google Scholar 

  15. 15.

    Tang, J. et al. Colloidal-quantum-dot photovoltaics using atomic-ligand passivation. Nat. Mater. 10, 765–771 (2011).

    ADS  Article  Google Scholar 

  16. 16.

    Chuang, C.-H. M., Brown, P. R., Bulović, V. & Bawendi, M. G. Improved performance and stability in quantum dot solar cells through band alignment engineering. Nat. Mater. 13, 796–801 (2014).

    ADS  Article  Google Scholar 

  17. 17.

    Zhang, H., Jang, J., Liu, W. & Talapin, D. V. Colloidal nanocrystals with inorganic halide, pseudohalide, and halometallate ligands. ACS Nano 8, 7359–7369 (2014).

    Article  Google Scholar 

  18. 18.

    Kovalenko, M. V., Scheele, M. & Talapin, D. V. Colloidal nanocrystals with molecular metal chalcogenide surface ligands. Science 324, 1417–1420 (2009).

    ADS  Article  Google Scholar 

  19. 19.

    Choi, J. J. et al. Photogenerated exciton dissociation in highly coupled lead salt nanocrystal assemblies. Nano Lett. 10, 1805–1811 (2010).

    ADS  Article  Google Scholar 

  20. 20.

    Sun, L. F. et al. Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control. Nat. Nanotech. 7, 369–373 (2012).

    ADS  Article  Google Scholar 

  21. 21.

    Lee, K.-H. et al. Over 40 cd/A efficient green quantum dot electroluminescent device comprising uniquely large-sized quantum dots. ACS Nano 8, 4893–4901 (2014).

    Article  Google Scholar 

  22. 22.

    Owen, J. S., Park, J., Trudeau, P.-E. & Alivisatos, A. P. Reaction chemistry and ligand exchange at cadmium−selenide nanocrystal surfaces. J. Am. Chem. Soc. 130, 12279–12281 (2008).

    Article  Google Scholar 

  23. 23.

    Zanella, M. et al. Atomic ligand passivation of colloidal nanocrystal films via their reaction with propyltrichlorosilane. Chem. Mater. 25, 1423–1429 (2013).

    Article  Google Scholar 

  24. 24.

    Ji, C. et al. 1,2-Ethanedithiol treatment for AgIn5S8/ZnS quantum dot light-emitting diodes with high brightness. ACS Appl. Mater. Inter. 9, 8187–8193 (2017).

    Article  Google Scholar 

  25. 25.

    Daekyoung, K. et al. Improved electroluminescence of quantum dot light-emitting diodes enabled by a partial ligand exchange with benzenethiol. Nanotechnology 27, 245203 (2016).

    Article  Google Scholar 

  26. 26.

    Pan, J. et al. Highly efficient perovskite-quantum-dot light-emitting diodes by surface engineering. Adv. Mater. 28, 8718–8725 (2016).

    Article  Google Scholar 

  27. 27.

    Yang, Z. et al. All-quantum-dot infrared light-emitting diodes. ACS Nano 9, 12327–12333 (2015).

    Article  Google Scholar 

  28. 28.

    Dirin, D. N. et al. Lead halide perovskites and other metal halide complexes as inorganic capping ligands for colloidal nanocrystals. J. Am. Chem. Soc. 136, 6550–6553 (2014).

    Article  Google Scholar 

  29. 29.

    Bae, W. K. et al. Highly efficient green-light-emitting diodes based on CdSe@ZnS quantum dots with a chemical-composition gradient. Adv. Mater. 21, 1690–1694 (2009).

    Article  Google Scholar 

  30. 30.

    Bae, W. K., Nam, M. K., Char, K. & Lee, S. Gram-scale one-pot synthesis of highly luminescent blue emitting Cd1−xZn x S/ZnS nanocrystals. Chem. Mater. 20, 5307–5313 (2008).

    Article  Google Scholar 

  31. 31.

    Lim, J. et al. Influence of shell thickness on the performance of light-emitting devices based on CdSe/Zn1–xCd x S core/shell heterostructured quantum dots. Adv. Mater. 26, 8034–8040 (2014).

    ADS  Article  Google Scholar 

  32. 32.

    Adachi, M. M. et al. Microsecond-sustained lasing from colloidal quantum dot solids. Nat. Commun. 6, 8694 (2015).

    Article  Google Scholar 

  33. 33.

    Lan, X. et al. Passivation using molecular halides increases quantum dot solar cell performance. Adv. Mater. 28, 299–304 (2016).

    ADS  Article  Google Scholar 

  34. 34.

    Ning, Z. et al. Air-stable n-type colloidal quantum dot solids. Nat. Mater. 13, 822–828 (2014).

    ADS  Article  Google Scholar 

  35. 35.

    Di Raddo, P. A convenient method of esterification of fatty acids: An undergraduate organic laboratory experiment. J. Chem. Educ. 70, 1034 (1993).

    Article  Google Scholar 

  36. 36.

    Montalbetti, C. A. & Falque, V. Amide bond formation and peptide coupling. Tetrahedron 61, 10827–10852 (2005).

    Article  Google Scholar 

  37. 37.

    Bae, W. K. et al. Highly effective surface passivation of PbSe quantum dots through reaction with molecular chlorine. J. Am. Chem. Soc. 134, 20160–20168 (2012).

    Article  Google Scholar 

  38. 38.

    Bae, W. K. et al. Controlling the influence of Auger recombination on the performance of quantum-dot light-emitting diodes. Nat. Commun. 4, 2661 (2013).

    Google Scholar 

  39. 39.

    Blakesley, J. C. et al. Towards reliable charge-mobility benchmark measurements for organic semiconductors. Org. Electron. 15, 1263–1272 (2014).

    Article  Google Scholar 

  40. 40.

    Baranovski, S. Charge Transport in Disordered Solids with Applications in Electronics Vol. 17 (John Wiley & Sons, Chichester, 2006).

  41. 41.

    Talgorn, E. et al. Unity quantum yield of photogenerated charges and band-like transport in quantum-dot solids. Nat. Nanotech. 6, 733–739 (2011).

    ADS  Article  Google Scholar 

  42. 42.

    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 

  43. 43.

    Kwak, J. et al. Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure. Nano Lett. 12, 2362–2366 (2012).

    ADS  Article  Google Scholar 

  44. 44.

    Pan, J. et al. Size tunable zno nanoparticles to enhance electron injection in solution processed QLEDs. ACS Photon. 3, 215–222 (2016).

    Article  Google Scholar 

  45. 45.

    Helander, M. G. et al. Chlorinated indium tin oxide electrodes with high work function for organic device compatibility. Science 332, 944–947 (2011).

    ADS  Article  Google Scholar 

  46. 46.

    Piprek, J., Romer, F. & Witzigmann, B. On the uncertainty of the Auger recombination coefficient extracted from InGaN/GaN light-emitting diode efficiency droop measurements. Appl. Phys. Lett. 106, 101101 (2015).

    ADS  Article  Google Scholar 

  47. 47.

    Bae, W. K. et al. Controlled alloying of the core–shell interface in CdSe/CdS quantum dots for suppression of Auger recombination. ACS Nano 7, 3411–3419 (2013).

    Article  Google Scholar 

  48. 48.

    Dong, Y. et al. 20.2: Ultra-bright, highly efficient, low roll-off inverted quantum-dot light emitting devices (QLEDs). SID Symp. Dig. Tech. Pap 46, 270–273 (2015).

    Article  Google Scholar 

  49. 49.

    Fan, F. et al. Continuous-wave lasing in colloidal quantum dot solids enabled by facet-selective epitaxy. Nature 544, 75–79 (2017).

    ADS  Article  Google Scholar 

  50. 50.

    Burgelman, M., Decock, K., Khelifi, S.Abass, A. Advanced electrical simulation of thin film solar cells. Thin Solid Film. 535, 296–301 (2013).

    ADS  Article  Google Scholar 

Download references

Acknowledgements

This publication is based in part on work supported by the Ontario Research Fund Research Excellence Program, and by the Natural Sciences and Engineering Research Council (NSERC) of Canada. The authors thank B. Sun, M. Liu, M. Burgelman, P.-C. Li and R. Munir for their help during the course of study.

Author information

Affiliations

Authors

Contributions

X.L. and F.F. conceived the idea. X.L. and F.F. developed the efficient chlorination exchange. X.L. and Y.-B.Z. fabricated and characterized the QLEDs. O.V. performed optoelectronic device simulations. L.L. and X.L. synthesized the CQDs. M.L. undertook SEM imaging. R.Q.-B. performed XPS characterizations. X.L., F.F., O.V., E.H.S. and Y.-B.Z. wrote the manuscript. O.V., E.H.S. and Z.-H.L supervised the project. All authors discussed the results and assisted in manuscript preparation.

Corresponding authors

Correspondence to Fengjia Fan or Oleksandr Voznyy or Zheng-Hong Lu or Edward H. Sargent.

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.

Supplementary information

Supplementary Information

Supplementary Tables, Figures and Analysis.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Li, X., Zhao, Y., Fan, F. et al. Bright colloidal quantum dot light-emitting diodes enabled by efficient chlorination. Nature Photon 12, 159–164 (2018). https://doi.org/10.1038/s41566-018-0105-8

Download citation

Further reading

Search

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