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Ultrafast Charge Transfer from CdSe Quantum Dots to p-Type NiO: Hole Injection vs Hole Trapping

Zheng, Kaibo LU ; Zidek, Karel LU ; Qenawy, Mohamed LU ; Zhang, Wei LU ; Chabera, Pavel LU ; Lenngren, Nils LU ; Yartsev, Arkady LU and Pullerits, Tönu LU (2014) In Journal of Physical Chemistry C 118(32). p.18462-18471
Abstract
Semiconductor quantum dot (QD) to metal oxide electron injection dynamics is well documented in the scientific literature. In contrast to that, not much is known so far about hole injection time scales in such systems. The current study fills this gap. We investigate photocathodes consisting of CdSe QDs and p-type NiO to study hole injection dynamics from the valence band of the QDs to NiO. The combination of two complementary techniques, ultrafast time-resolved absorption and fluorescence spectroscopies, enabled us to distinguish between hole trapping and injection. A kinetic component on the time scale of a few hundreds of picoseconds was identified as hole injection. By changing the size of the QDs, the driving force of the hole... (More)
Semiconductor quantum dot (QD) to metal oxide electron injection dynamics is well documented in the scientific literature. In contrast to that, not much is known so far about hole injection time scales in such systems. The current study fills this gap. We investigate photocathodes consisting of CdSe QDs and p-type NiO to study hole injection dynamics from the valence band of the QDs to NiO. The combination of two complementary techniques, ultrafast time-resolved absorption and fluorescence spectroscopies, enabled us to distinguish between hole trapping and injection. A kinetic component on the time scale of a few hundreds of picoseconds was identified as hole injection. By changing the size of the QDs, the driving force of the hole injection was tuned and we demonstrated that the hole injection rates are well described by the Marcus theory of charge transfer. In order to enhance the overall hole injection efficiency, we have passivated the CdSe QDs by a gradient ZnS shell. The core-shell QDs show significantly slower hole injection; still, since trapping was almost eliminated, the overall hole injection efficiency was greatly enhanced. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry C
volume
118
issue
32
pages
18462 - 18471
publisher
The American Chemical Society
external identifiers
  • wos:000340444500022
  • scopus:84906266068
ISSN
1932-7447
DOI
10.1021/jp506963q
language
English
LU publication?
yes
id
dd7a9aac-6c90-4f8a-a06a-b15103285efd (old id 4656316)
date added to LUP
2014-09-24 14:11:35
date last changed
2017-11-19 03:06:17
@article{dd7a9aac-6c90-4f8a-a06a-b15103285efd,
  abstract     = {Semiconductor quantum dot (QD) to metal oxide electron injection dynamics is well documented in the scientific literature. In contrast to that, not much is known so far about hole injection time scales in such systems. The current study fills this gap. We investigate photocathodes consisting of CdSe QDs and p-type NiO to study hole injection dynamics from the valence band of the QDs to NiO. The combination of two complementary techniques, ultrafast time-resolved absorption and fluorescence spectroscopies, enabled us to distinguish between hole trapping and injection. A kinetic component on the time scale of a few hundreds of picoseconds was identified as hole injection. By changing the size of the QDs, the driving force of the hole injection was tuned and we demonstrated that the hole injection rates are well described by the Marcus theory of charge transfer. In order to enhance the overall hole injection efficiency, we have passivated the CdSe QDs by a gradient ZnS shell. The core-shell QDs show significantly slower hole injection; still, since trapping was almost eliminated, the overall hole injection efficiency was greatly enhanced.},
  author       = {Zheng, Kaibo and Zidek, Karel and Qenawy, Mohamed and Zhang, Wei and Chabera, Pavel and Lenngren, Nils and Yartsev, Arkady and Pullerits, Tönu},
  issn         = {1932-7447},
  language     = {eng},
  number       = {32},
  pages        = {18462--18471},
  publisher    = {The American Chemical Society},
  series       = {Journal of Physical Chemistry C},
  title        = {Ultrafast Charge Transfer from CdSe Quantum Dots to p-Type NiO: Hole Injection vs Hole Trapping},
  url          = {http://dx.doi.org/10.1021/jp506963q},
  volume       = {118},
  year         = {2014},
}