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Stable and efficient quantum-dot light-emitting diodes based on solution-processed multilayer structures

Abstract

Multilayer, colloidal quantum-dot based light-emitting diodes that exhibit high brightness, solution processability, colour tunability and narrow emission bandwidth are reported. These devices consist of a quantum-dot emissive layer sandwiched between an organic hole transport layer and an electron transport layer of ZnO nanoparticles, all of which are deposited using a solution process. The devices have maximum luminance and power efficiency values of 4,200 cd m−2 and 0.17 lm W−1 for blue emission, 68,000 cd m−2 and 8.2 lm W−1 for green, and 31,000 cd m−2 and 3.8 lm W−1 for orange-red. Moreover, with the incorporation of the ZnO nanoparticles, these devices exhibit high environmental stability, and the unencapsulated devices have operating lifetimes exceeding 250 h in low vacuum with an initial brightness of 600 cd m−2.

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Figure 1: Crystallinity and XRD data, schematic of layered device, and energy levels of the ZnO nanoparticle-based QD-LED.
Figure 2: Electroluminescence performance of ZnO nanoparticle-based QD-LEDs with blue, green and orange-red emission.
Figure 3: Dependence of QD-LED performance on ZnO and QD layer thickness.
Figure 4: Electroluminescence spectra and CIE coordinates of the QD-LEDs.
Figure 5: Stability data for an unencapsulated green-emitting ZnO nanoparticle-based QD-LED.

References

  1. 1

    Anikeeva, P. O., Halpert, J. E., Bawendi, M. G. & Bulovic, V. Electroluminescence from a mixed red-green-blue colloidal quantum dot monolayer. Nano Lett. 7, 2196–2200 (2007).

    ADS  Article  Google Scholar 

  2. 2

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

    ADS  Article  Google Scholar 

  3. 3

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

    ADS  Article  Google Scholar 

  4. 4

    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 

  5. 5

    Sun, Q. et al. Bright, multicoloured light-emitting diodes based on quantum dots. Nature Photon. 1, 717–722 (2007).

    ADS  Article  Google Scholar 

  6. 6

    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 

  7. 7

    Feng, X. J. et al. Vertically aligned single crystal TiO2 nanowire arrays grown directly on transparent conducting oxide coated glass: synthesis details and applications. Nano Lett. 8, 3781–3786 (2008).

    ADS  Article  Google Scholar 

  8. 8

    Qian, L. et al. Electroluminescence in light emitting polymers at sub-bandgap voltages. Nano Today 5, 384–389 (2010).

    Article  Google Scholar 

  9. 9

    Forrest, S. R. The path to ubiquitous and low-cost organic electronic appliances on plastic. Nature 428, 911–918 (2004).

    ADS  Article  Google Scholar 

  10. 10

    Beek, W. J. E., Wienk, M. M. & Janssen, R. A. J. Efficient hybrid solar cells from zinc oxide nanoparticles and a conjugated polymer. Adv. Mater. 16, 1009–1013 (2004).

    Article  Google Scholar 

  11. 11

    Ravirajan, P. et al. Hybrid polymer/zinc oxide photovoltaic devices with vertically oriented ZnO nanorods and an amphiphilic molecular interface layer. J. Phys. Chem. B 110, 7635–7639 (2006).

    Article  Google Scholar 

  12. 12

    Tan, Z. N. et al. Bright and color-saturated emission from blue light-emitting diodes based on solution-processed colloidal nanocrystal quantum dots. Nano Lett. 7, 3803–3807 (2007).

    ADS  Article  Google Scholar 

  13. 13

    Pandey, A. K. & Nunzi, J. M. Rubrene/fullerene heterostructures with a half-gap electroluminescence threshold and large photovoltage. Adv. Mater. 19, 3613–3617 (2007).

    Article  Google Scholar 

  14. 14

    Roest, A. L., Kelly, J. J., Vanmaekelbergh, D. & Meulenkamp, E. A. Staircase in the electron mobility of a ZnO quantum dot assembly due to shell filling. Phys. Rev. Lett. 89, 036801 (2002).

    ADS  Article  Google Scholar 

  15. 15

    Eom, S. H. et al. Effect of electron injection and transport materials on efficiency of deep-blue phosphorescent organic light-emitting devices. Org. Electron. 10, 686–691 (2009).

    Article  Google Scholar 

  16. 16

    Coe-Sullivan, S., Steckel, J. S., Woo, W. K., Bawendi, M. G. & Bulovic, V. Large-area ordered quantum-dot monolayers via phase separation during spin-casting. Adv. Funct. Mater. 15, 1117–1124 (2005).

    Article  Google Scholar 

  17. 17

    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 

  18. 18

    Aziz, H. et al. Degradation processes at the cathode/organic interface in organic light emitting devices with Mg:Ag cathodes. Appl. Phys. Lett. 72, 2642–2644 (1998).

    ADS  Article  Google Scholar 

  19. 19

    Pechstedt, K., Whittle, T., Baumberg, J. & Melvin, T. Photoluminescence of colloidal CdSe/ZnS quantum dots: the critical effect of water molecules. J. Phys. Chem. C 114, 12069–12077 (2010).

    Article  Google Scholar 

  20. 20

    Cordero, S. R., Carson, P. J., Estabrook, R. A., Strouse, G. F. & Buratto, S. K. Photo-activated luminescence of CdSe quantum dot monolayers. J. Phys. Chem. B 104, 12137–12142 (2000).

    Article  Google Scholar 

  21. 21

    Dembski, S. et al. Photoactivation of CdSe/ZnS quantum dots embedded in silica colloids. Small 4, 1516–1526 (2008).

    Article  Google Scholar 

  22. 22

    Yang, H. & Holloway, P. H. Efficient and photostable ZnS-passivated CdS:Mn luminescent nanocrystals. Adv. Funct. Mater. 14, 152–156 (2004).

    Article  Google Scholar 

  23. 23

    Bae, W. K., Char, K., Hur, H. & Lee, S. Single-step synthesis of quantum dots with chemical composition gradients. Chem. Mater. 20, 531–539 (2008).

    Article  Google Scholar 

  24. 24

    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 

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Acknowledgements

L.Q. and P.H.H. were supported by the Army Research Office (grant no. W911NF-07-1-0545). Y.Z. and J.X. were partially supported by the US Department of Energy (grant no. DE-FG36-08GO18020) and the Florida Energy Systems Consortium. Assistance in data collection and reduction by E. Lambers and K. Siebein of the Major Analytical Instrumentation Center at the University of Florida is gratefully acknowledged.

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L.Q. and Y.Z. synthesized material, fabricated devices, collected performance data and postulated mechanisms to explain the excellent performance of the QD-LEDs. J.X. and P.H.H. supervised the synthesis of material and devices, directed the collection and reduction of performance data, designed tests for the postulated mechanisms, and finalized the manuscript.

Corresponding authors

Correspondence to Jiangeng Xue or Paul H. Holloway.

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The authors declare no competing financial interests.

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Qian, L., Zheng, Y., Xue, J. et al. Stable and efficient quantum-dot light-emitting diodes based on solution-processed multilayer structures. Nature Photon 5, 543–548 (2011). https://doi.org/10.1038/nphoton.2011.171

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