Issue 18, 2009
From the journal:

Physical Chemistry Chemical Physics

Ligand-dependent blinking of zinc-blende CdSe/ZnS core/shell nanocrystals†

Yongwook Kim,a   Nam Woong Song,*bc   Hyunung Yu,b   Dae Won Moon,b   Sung Jun Lim,a   Wonjung Kim,a   Hye-Joo Yoona  and  Seung Koo Shin*a  

* Corresponding authors

a Bionanotechnology Center, Department of Chemistry, Pohang University of Science and Technology, San31 Hyoja-dong Nam-gu Pohang, Kyungbuk, Korea
E-mail: skshin@postech.ac.kr
Fax: +82 (0)54 279 3399
Tel: +82 (0)54 279 2123

b Nanobio Fusion Research Center, Korea Research Institute of Standards and Science, 1 Doryong-dongYuseong-gu, Daejeon, Korea
E-mail: nwsong@kriss.re.kr
Fax: +82 (0)42 868 5032
Tel: +82 (0)42 868 5214

c Cell Dynamics Research Center, Gwangju Institute of Science and Technology, 261 Oryong-dong Buk-gu, Gwangju, Korea

Abstract

Blinking of zinc-blende CdSe/ZnS core/shell nanocrystals are studied as a function of surface passivating ligands. Organic-soluble CdSe/ZnS core/shell nanocrystals are prepared by colloidal synthesis free of trioctylphosphine oxide and converted into water-soluble ones by ligand exchange with three different hydrophilic thiols, 2-aminoethanethiol, 3-mercapto-1-propanol, and 3-mercaptopropionic acid. The zinc-blende lattice structure is confirmed by powder X-ray diffraction, the size and shape distributions are visualized by high-resolution transmission electron microscopy, and hydrodynamic size distributions of water-soluble nanocrystals are determined by dynamic light scattering. Ligand-dependent optical properties, such as the absorption and emission spectra as well as the photoluminescence lifetime, are obtained in both solution and glass substrate to characterize the effects of ligand on the bright state of nanocrystals. The time trace of blinking is recorded for single nanocrystals in polymer film. Both on- and off-time distributions are fit to a power law. The off-time exponents are clustered at 1.67 ± 0.05, whereas the on-time exponents are scattered in the range of 1.71–2.25. The thiolate conjugation on the surface zinc atom greatly reduces the on-time duration, suggesting that the rate of photoinduced charge separation from the bright (on) to the dark (off) state increases as the number of surface hole-trap states increases.

Graphical abstract: Ligand-dependent blinking of zinc-blende CdSe/ZnS core/shell nanocrystals

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Article information

DOI
https://doi.org/10.1039/B822351C
Article type
Paper
Submitted
12 Dec 2008
Accepted
05 Feb 2009
First published
03 Mar 2009

Phys. Chem. Chem. Phys., 2009,11, 3497-3502

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Ligand-dependent blinking of zinc-blende CdSe/ZnS core/shell nanocrystals

Y. Kim, N. W. Song, H. Yu, D. W. Moon, S. J. Lim, W. Kim, H. Yoon and S. Koo Shin, Phys. Chem. Chem. Phys., 2009, 11, 3497 DOI: 10.1039/B822351C

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