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Directed Energy Transfer in Films of CdSe Quantum Dots: Beyond the Point Dipole Approximation

Zheng, Kaibo LU ; Zidek, Karel LU ; Qenawy, Mohamed LU ; Zhu, Nan; Chabera, Pavel LU ; Lenngren, Nils LU ; Chi, Qijin and Pullerits, Tönu LU (2014) In Journal of the American Chemical Society 136(17). p.6259-6268
Abstract
Understanding of Forster resonance energy transfer (FRET) in thin films composed of quantum dots (QDs) is of fundamental and technological significance in optimal design of QD based optoelectronic devices. The separation between QDs in the densely packed films is usually smaller than the size of QDs, so that the simple point dipole approximation, widely used in the conventional approach, can no longer offer quantitative description of the FRET dynamics in such systems. Here, we report the investigations of the FRET dynamics in densely packed films composed of multisized CdSe QDs using ultrafast transient absorption spectroscopy and theoretical modeling. Pairwise interdot transfer time was determined in the range of 1.5 to 2 ns by spectral... (More)
Understanding of Forster resonance energy transfer (FRET) in thin films composed of quantum dots (QDs) is of fundamental and technological significance in optimal design of QD based optoelectronic devices. The separation between QDs in the densely packed films is usually smaller than the size of QDs, so that the simple point dipole approximation, widely used in the conventional approach, can no longer offer quantitative description of the FRET dynamics in such systems. Here, we report the investigations of the FRET dynamics in densely packed films composed of multisized CdSe QDs using ultrafast transient absorption spectroscopy and theoretical modeling. Pairwise interdot transfer time was determined in the range of 1.5 to 2 ns by spectral analyses which enable separation of the FRET contribution from intrinsic exciton decay. A rational model is suggested by taking into account the distribution of the electronic transition densities in the dots and using the film morphology revealed by AFM images. The FRET dynamics predicted by the model are in good quantitative agreement with experimental observations without adjustable parameters. Finally, we use our theoretical model to calculate dynamics of directed energy transfer in ordered multilayer QD films, which we also observe experimentally. The Monte Carlo simulations reveal that three ideal QD monolayers can provide exciton funneling efficiency above 80% from the most distant layer. Thereby, utilization of directed energy transfer can significantly improve light harvesting efficiency of QD devices. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of the American Chemical Society
volume
136
issue
17
pages
6259 - 6268
publisher
The American Chemical Society
external identifiers
  • pmid:24684141
  • wos:000335369200028
  • scopus:84899730878
ISSN
1520-5126
DOI
10.1021/ja411127w
language
English
LU publication?
yes
id
18e576df-f051-4553-9b9a-47392fdd59f9 (old id 4482565)
date added to LUP
2014-06-19 14:38:26
date last changed
2017-09-24 04:01:18
@article{18e576df-f051-4553-9b9a-47392fdd59f9,
  abstract     = {Understanding of Forster resonance energy transfer (FRET) in thin films composed of quantum dots (QDs) is of fundamental and technological significance in optimal design of QD based optoelectronic devices. The separation between QDs in the densely packed films is usually smaller than the size of QDs, so that the simple point dipole approximation, widely used in the conventional approach, can no longer offer quantitative description of the FRET dynamics in such systems. Here, we report the investigations of the FRET dynamics in densely packed films composed of multisized CdSe QDs using ultrafast transient absorption spectroscopy and theoretical modeling. Pairwise interdot transfer time was determined in the range of 1.5 to 2 ns by spectral analyses which enable separation of the FRET contribution from intrinsic exciton decay. A rational model is suggested by taking into account the distribution of the electronic transition densities in the dots and using the film morphology revealed by AFM images. The FRET dynamics predicted by the model are in good quantitative agreement with experimental observations without adjustable parameters. Finally, we use our theoretical model to calculate dynamics of directed energy transfer in ordered multilayer QD films, which we also observe experimentally. The Monte Carlo simulations reveal that three ideal QD monolayers can provide exciton funneling efficiency above 80% from the most distant layer. Thereby, utilization of directed energy transfer can significantly improve light harvesting efficiency of QD devices.},
  author       = {Zheng, Kaibo and Zidek, Karel and Qenawy, Mohamed and Zhu, Nan and Chabera, Pavel and Lenngren, Nils and Chi, Qijin and Pullerits, Tönu},
  issn         = {1520-5126},
  language     = {eng},
  number       = {17},
  pages        = {6259--6268},
  publisher    = {The American Chemical Society},
  series       = {Journal of the American Chemical Society},
  title        = {Directed Energy Transfer in Films of CdSe Quantum Dots: Beyond the Point Dipole Approximation},
  url          = {http://dx.doi.org/10.1021/ja411127w},
  volume       = {136},
  year         = {2014},
}