Issue 25, 2023

Defect passivation and electron band energy regulation of a ZnO electron transport layer through synergetic bifunctional surface engineering for efficient quantum dot light-emitting diodes

Abstract

Zinc oxide nanoparticles (ZnO NPs) have been actively pursued as the most effective electron transport layer for quantum-dot light-emitting diodes (QLEDs) in light of their unique optical and electronic properties and low-temperature processing. However, the high electron mobility and smooth energy level alignment at QDs/ZnO/cathode interfaces cause electron over-injection, which aggravates non-radiative Auger recombination. Meanwhile, the abundant defects hydroxyl group (–OH) and oxygen vacancies (OV) in ZnO NPs act as trap states inducing exciton quenching, which synergistically reduces the effective radiation recombination for degrading the device performance. Here, we develop a bifunctional surface engineering strategy to synthesize ZnO NPs with low defect density and high environmental stability by using ethylenediaminetetraacetic acid dipotassium salt (EDTAK) as an additive. The additive effectively passivates surface defects in ZnO NPs and induces chemical doping simultaneously. Bifunctional engineering alleviates electron excess injection by elevating the conduction band level of ZnO to promote charge balance. As a result, state-of-the-art blue QLEDs with an EQE of 16.31% and a T50@100 cd m−2 of 1685 h are achieved, providing a novel and effective strategy to fabricate blue QLEDs with high efficiency and a long operating lifetime.

Graphical abstract: Defect passivation and electron band energy regulation of a ZnO electron transport layer through synergetic bifunctional surface engineering for efficient quantum dot light-emitting diodes

Supplementary files

Article information

Article type
Paper
Submitted
15 Cig 2023
Accepted
21 Cax 2023
First published
22 Cax 2023

Nanoscale, 2023,15, 10677-10684

Defect passivation and electron band energy regulation of a ZnO electron transport layer through synergetic bifunctional surface engineering for efficient quantum dot light-emitting diodes

F. Cai, Y. Tu, D. Tian, Y. Fang, B. Hou, M. Ishaq, X. Jiang, M. Li, S. Wang and Z. Du, Nanoscale, 2023, 15, 10677 DOI: 10.1039/D3NR01194A

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