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Open AccessArticle

Optical Properties, Morphology, and Stability of Iodide-Passivated Lead Sulfide Quantum Dots

1
Center “Information Optical Technologies”, ITMO University, 49 Kronverksky Pr., St. Petersburg 197101, Russia
2
College of Materials Science, Jilin University, Changchun 130012, China
*
Author to whom correspondence should be addressed.
Materials 2019, 12(19), 3219; https://doi.org/10.3390/ma12193219
Received: 31 July 2019 / Revised: 20 September 2019 / Accepted: 27 September 2019 / Published: 1 October 2019
Iodide atomic surface passivation of lead chalcogenides has spawned a race in efficiency of quantum dot (QD)-based optoelectronic devices. Further development of QD applications requires a deeper understanding of the passivation mechanisms. In the first part of the current study, we compare optics and electrophysical properties of lead sulfide (PbS) QDs with iodine ligands, obtained from different iodine sources. Methylammonium iodide (MAI), lead iodide (PbI2), and tetrabutylammonium iodide (TBAI) were used as iodine precursors. Using ultraviolet photoelectron spectroscopy, we show that different iodide sources change the QD HOMO/LUMO levels, allowing their fine tuning. AFM measurements suggest that colloidally-passivated QDs result in formation of more uniform thin films in one-step deposition. The second part of this paper is devoted to the PbS QDs with colloidally-exchanged shells (i.e., made from MAI and PbI2). We especially focus on QD optical properties and their stability during storage in ambient conditions. Colloidal lead iodide treatment is found to reduce the QD film resistivity and improve photoluminescence quantum yield (PLQY). At the same time stability of such QDs is reduced. MAI-treated QDs are found to be more stable in the ambient conditions but tend to agglomerate, which leads to undesirable changes in their optics. View Full-Text
Keywords: quantum dots; lead sulfide; ligand exchange; iodide; stability quantum dots; lead sulfide; ligand exchange; iodide; stability
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Skurlov, I.D.; Korzhenevskii, I.G.; Mudrak, A.S.; Dubavik, A.; Cherevkov, S.A.; Parfenov, P.S.; Zhang, X.; Fedorov, A.V.; Litvin, A.P.; Baranov, A.V. Optical Properties, Morphology, and Stability of Iodide-Passivated Lead Sulfide Quantum Dots. Materials 2019, 12, 3219.

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