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Balanced charge carrier transport mediated by quantum dot film post-organization for light-emitting diode applications

Cho, Yuljae, Lim, Jongchul, Li, Meng, Pak, Sangyeon, Wang, Zhao-Kui, Yang, Ying-Guo, Abate, Antonio, Li, Zhe, Snaith, Henry J., Hou, Bo ORCID: https://orcid.org/0000-0001-9918-8223 and Cha, SeungNam 2021. Balanced charge carrier transport mediated by quantum dot film post-organization for light-emitting diode applications. ACS Applied Materials and Interfaces 13 (22) , pp. 26170-26179. 10.1021/acsami.1c04821

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Abstract

In light-emitting diodes (LEDs), balanced electron and hole transport is of particular importance to achieve high rates of radiative recombination. Most quantum dot (QD)-based LEDs, however, employ infinitesimal core–shell QDs which inherently have different electron and hole mobilities. As QDs are the core building blocks of QD-LEDs, the inherent mobility difference in the core–shell QDs causes significantly unbalanced charge carrier transport, resulting in detrimental effects on performances of QD-LEDs. Herein, we introduce a post-chemical treatment to reconstruct the QD films through the solvent-mediated self-organization process. The treatment using various poly-alkyl alcohol groups enables QD ensembles to transform from disordered solid dispersion into an ordered superlattice and effectively modulate electron and hole mobilities, which leads to the balanced charge carrier transport. In particular, ethanol-treated QD films exhibit enhanced charge carrier lifetime and reduced hysteresis due to the balanced charge carrier transport, which is attributed to the preferential-facet-oriented QD post-organization. As a result, 63, 78, and 54% enhancements in the external quantum efficiency were observed in red, green, and blue QD-LEDs, respectively. These results are of fundamental importance to understand both solvent-mediated QD film reconstruction and the effect of balanced electron and hole transport in QD-LEDs.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Publisher: American Chemical Society
ISSN: 1944-8244
Date of First Compliant Deposit: 1 June 2021
Date of Acceptance: 18 May 2021
Last Modified: 05 Nov 2022 18:32
URI: https://orca.cardiff.ac.uk/id/eprint/141690

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