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


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.


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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.

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Correspondence to Jiangeng Xue or Paul H. Holloway.

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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).

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