Correlation of near-unity quantum yields with photogenerated excitons in X-type ligand passivated CsPbBr3 perovskite quantum dots

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We investigated the exciton decay dynamics of CsPbBr3 perovskite quantumdots (PQDs) through an X-type ligand passivation process. 1-Dodecanethiol (DDT), as an X-type ligand, covers Br vacancies of PQDs and then the photoluminescence quantum yield (PLQY) sharply improved from 76.1% to 99.8%. Impressively, after passivation, the photoluminescence (PL) lifetime of PQDs decreased from 3.16 ns to 2.42 ns, contrary to the PLQY increase. To clarify this phenomenon, we observed exciton decay dynamics by varying the temperature. Thereby, we found that shallow traps from Br vacancies not only reduce the PLQY but also induce a longer lifetime related to the nonradiative exciton decay leading to an increase in the lifetime. Our results are novel and important in a way that we provide a systematic understanding of the exciton decay dynamics by combining two key concepts together: (1) near unity PLQY via ligand engineering and (2) temperature-dependent photogenerated excitons.
Publisher
ROYAL SOC CHEMISTRY
Issue Date
2019-08
Language
English
Article Type
Article
Citation

NANOSCALE ADVANCES, v.1, no.8, pp.2828 - 2834

ISSN
2516-0230
DOI
10.1039/c9na00292h
URI
http://hdl.handle.net/10203/265535
Appears in Collection
MS-Journal Papers(저널논문)
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