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Efficient Quantum Dot Light-Emitting Diodes with Zn0.85Mg0.15O Interfacial Modification Layer

Abstract

Efficient inverted quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated by using 15% Mg doped ZnO (Zn0.85Mg0.15O) as interfacial modification layer. By doping Mg into ZnO, the conduction band level, the density of oxygen vacancies and the conductivity of the ZnO can be tuned. To suppress excess electron injection, a 13 nm Zn0.85Mg0.15O interlayer with relatively higher conduction band edge and lower conductivity is inserted between ZnO electron transport layer and QD light-emitting layer, which improves the balance of charge injection and blocks the non-radiative pathway. Moreover, according to the electrical and the optical studies of devices and materials, quenching sites at ZnO surface are effectively reduced by Mg-doping. Therefore exciton quenching induced by ZnO nanoparticles is largely suppressed by capping ZnO with Zn0.85Mg0.15O. Consequently, the red QLEDs with Zn0.85Mg0.15O interfacial modification layer exhibit superior performance with maximum current efficiency of 18.69 cd/A and peak external quantum efficiency of 13.57%, which are about 1.72- and 1.74-fold higher than 10.88 cd/A and 7.81% of the devices without Zn0.85Mg0.15O. Similar improvements are also achieved in green QLEDs. Our results indicate that Zn0.85Mg0.15O can serve as an effective interfacial modification layer for suppressing the exciton quenching and improving the charge balance of the devices.

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Publication details

The article was received on 24 Mar 2017, accepted on 03 May 2017 and first published on 05 May 2017


Article type: Paper
DOI: 10.1039/C7NR02099F
Citation: Nanoscale, 2017, Accepted Manuscript
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    Efficient Quantum Dot Light-Emitting Diodes with Zn0.85Mg0.15O Interfacial Modification Layer

    Y. Sun, Y. Jiang, H. Peng, J. Wei, S. Zhang and S. Chen, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR02099F

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