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Engineering the spin-flip limited exciton dephasing in colloidal CdSe/CdS quantum dots

Nicolo Accanto, Francesco Masia, Iwan Moreels UGent, Zeger Hens UGent, Wolfgang Langbein and Paola Borri (2012) ACS NANO. 6(6). p.5227-5233
abstract
We have measured the intrinsic exciton dephasing in high-quality zinc blende CdSe/CdS colloidal quantum dots in the temperature range from 5 to 170 K using a sensitive three-beam photon echo technique in heterodyne detection, which is not affected by spectral diffusion. Pure dephasing via acoustic phonons dominates the initial dynamics, followed by an exponential zero-phonon line dephasing. From the temperature dependence of the zero-phonon line dephasing, the exciton lifetime, and the exciton thermalization within its fine structure, we show that the zero-phonon line dephasing of the lowest bright state originates from the phonon-assisted spin-flip to dark exciton states. Importantly, we can control the dephasing by tailoring the exciton fine structure through its dependence on the dot core size and shell thickness, as expected from the spin flip mechanism. By reducing the electron-hole exchange interaction with increasing core size and delocalization of the electron wave function in the quasi-type-II core/shell band alignment, we find the longest zero-phonon line dephasing time of similar to 110 ps at 5 K in dots with the largest core diameter (5.7 nm) and the thickest CdSe shell (9 monolayers) in the series studied.
Please use this url to cite or link to this publication:
author
organization
year
type
journalArticle (original)
publication status
published
subject
keyword
exciton dephasing, transient four-wave mixing, colloidal nanocystals, BAND-EDGE EXCITON, NANOCRYSTALS
journal title
ACS NANO
ACS Nano
volume
6
issue
6
pages
5227 - 5233
Web of Science type
Article
Web of Science id
000305661300073
JCR category
MATERIALS SCIENCE, MULTIDISCIPLINARY
JCR impact factor
12.062 (2012)
JCR rank
9/239 (2012)
JCR quartile
1 (2012)
ISSN
1936-0851
DOI
10.1021/nn300992a
project
Center for nano- and biophotonics (NB-Photonics)
language
English
UGent publication?
yes
classification
A1
copyright statement
I have transferred the copyright for this publication to the publisher
id
2979410
handle
http://hdl.handle.net/1854/LU-2979410
date created
2012-09-05 17:38:38
date last changed
2014-05-26 09:46:25
@article{2979410,
  abstract     = {We have measured the intrinsic exciton dephasing in high-quality zinc blende CdSe/CdS colloidal quantum dots in the temperature range from 5 to 170 K using a sensitive three-beam photon echo technique in heterodyne detection, which is not affected by spectral diffusion. Pure dephasing via acoustic phonons dominates the initial dynamics, followed by an exponential zero-phonon line dephasing. From the temperature dependence of the zero-phonon line dephasing, the exciton lifetime, and the exciton thermalization within its fine structure, we show that the zero-phonon line dephasing of the lowest bright state originates from the phonon-assisted spin-flip to dark exciton states. Importantly, we can control the dephasing by tailoring the exciton fine structure through its dependence on the dot core size and shell thickness, as expected from the spin flip mechanism. By reducing the electron-hole exchange interaction with increasing core size and delocalization of the electron wave function in the quasi-type-II core/shell band alignment, we find the longest zero-phonon line dephasing time of similar to 110 ps at 5 K in dots with the largest core diameter (5.7 nm) and the thickest CdSe shell (9 monolayers) in the series studied.},
  author       = {Accanto, Nicolo and Masia, Francesco and Moreels, Iwan and Hens, Zeger and Langbein, Wolfgang and Borri, Paola},
  issn         = {1936-0851},
  journal      = {ACS NANO},
  keyword      = {exciton dephasing,transient four-wave mixing,colloidal nanocystals,BAND-EDGE EXCITON,NANOCRYSTALS},
  language     = {eng},
  number       = {6},
  pages        = {5227--5233},
  title        = {Engineering the spin-flip limited exciton dephasing in colloidal CdSe/CdS quantum dots},
  url          = {http://dx.doi.org/10.1021/nn300992a},
  volume       = {6},
  year         = {2012},
}

Chicago
Accanto, Nicolo, Francesco Masia, Iwan Moreels, Zeger Hens, Wolfgang Langbein, and Paola Borri. 2012. “Engineering the Spin-flip Limited Exciton Dephasing in Colloidal CdSe/CdS Quantum Dots.” Acs Nano 6 (6): 5227–5233.
APA
Accanto, N., Masia, F., Moreels, I., Hens, Z., Langbein, W., & Borri, P. (2012). Engineering the spin-flip limited exciton dephasing in colloidal CdSe/CdS quantum dots. ACS NANO, 6(6), 5227–5233.
Vancouver
1.
Accanto N, Masia F, Moreels I, Hens Z, Langbein W, Borri P. Engineering the spin-flip limited exciton dephasing in colloidal CdSe/CdS quantum dots. ACS NANO. 2012;6(6):5227–33.
MLA
Accanto, Nicolo, Francesco Masia, Iwan Moreels, et al. “Engineering the Spin-flip Limited Exciton Dephasing in Colloidal CdSe/CdS Quantum Dots.” ACS NANO 6.6 (2012): 5227–5233. Print.