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

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 a...

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Bibliographic Details
Published in:Materials 2019-10, Vol.12 (19), p.3219
Main Authors: Skurlov, Ivan D., Korzhenevskii, Iurii G., Mudrak, Anastasiia S., Dubavik, Aliaksei, Cherevkov, Sergei A., Parfenov, Petr S., Zhang, Xiaoyu, Fedorov, Anatoly V., Litvin, Aleksandr P., Baranov, Alexander V.
Format: Article
Language:English
Subjects:
Colloids
Energy
Glass substrates
Iodine
Lead sulfides
Ligands
Molecular orbitals
Morphology
Optical properties
Optoelectronic devices
Passivity
Photoelectrons
Photoluminescence
Quantum dots
Spectrum analysis
Thin films
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Summary: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.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma12193219