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

Cai, Fensha, Tu, Yufei, Tian, Dadi, Fang, Yan, Jiang, Xiaohong, Hou, Bo ORCID: https://orcid.org/0000-0001-9918-8223, Ishaq, Muhammad, Li, Meng, Wang, Shujie and Du, Zuliang 2023. Defect passivation and electron band energy regulation of ZnO electron transport layer through a synergetic bifunctional surface engineering for efficient quantum dot light-emitting diodes. Nanoscale 15 (25) , p. 10677. 10.1039/D3NR01194A Item availability restricted.

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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, electronic properties and low-temperature processing. However, the high electron mobility and smooth energy level alignment at QDs/ZnO/cathode interfaces generate electron over-injection, which aggravates non-radiative Auger recombination. Meanwhile, the abundant defects (-OH and OV) in ZnO NPs act as trap states inducing exciton quenching, which synergistically reduces the effective radiation recombination for degrading 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. The bifunctional engineering leads to alleviate 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/m2 of 1685 h are achieved, providing a novel and effective strategy to fabricate blue QLEDs with high efficiency and long operating lifetime.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	Royal Society of Chemistry
ISSN:	2040-3364
Date of First Compliant Deposit:	7 June 2023
Date of Acceptance:	21 May 2023
Last Modified:	11 Dec 2023 10:05
URI:	https://orca.cardiff.ac.uk/id/eprint/160215

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