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KMID : 1059520160600060402
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Journal of the Korean Chemical Society
2016 Volume.60 No. 6 p.402 ~ p.409
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Electronic Structure and Elemental Composition of the Lead Sulfide Colloidal Quantum Dots Depending on the Types of Ligand and Post-Treatment
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Kim Tae-Gun
Choi Hye-Kyoung
Jeong So-Hee
Kim Jeong-Won
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Abstract
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Thin films of lead sulfide colloidal quantum dots (CQDs) of 2.8 nm in diameter are fabricated and their surfaces are passivated by 3-mercaptopropionic acid (MPA) ligand or hybrid type (MPA+CdCl2) ligand, respectively. The changes in valence band electronic structure and atomic composition of each PbS CQD film upon post-treatment such as air, N2 annealing or UV/Ozone have been studied by photoelectron spectroscopy. The air annealing makes the CQD fermi level to move toward the valence band leading to “p-type doping” regardless of ligand type. The UV/Ozone post-treatment generates Pb(OH)2, PbSOx and PbO on both CQD surfaces. But the amount of the PbO has been reduced in hybrid type ligand case, especially. That is probably because the extra Pb cations in (111) surface are additionally passivated by Cl2 ligand, which limits the reaction between the Pb cation and ozone.
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KEYWORD
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Colloidal quantum dot, Hybrid ligand, Electronic structure, Composition analysis, Ozone treatment
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