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Photoexcitation dynamics in electrochemically charged CdSe quantum dots : From hot carrier cooling to auger recombination of negative trions

Honarfar, Alireza LU ; Mourad, Hassan LU ; Lin, Weihua LU ; Polukeev, Alexey LU ; Rahaman, Ahibur LU ; Abdellah, Mohamed LU ; Chábera, Pavel LU ; Pankratova, Galina LU ; Gorton, Lo LU and Zheng, Kaibo LU , et al. (2020) In ACS Applied Energy Materials 3(12). p.12525-12531
Abstract

Fulfilling the potential of colloidal semiconductor quantum dots (QDs) in electrically driven applications remains a challenge largely since operation of such devices involves charged QDs with drastically different photophysical properties compared to their well-studied neutral counterparts. In this work, the full picture of excited state dynamics in charged CdSe QDs at various time scales has been revealed via transient absorption spectroscopy combined with electrochemistry as a direct manipulation tool to control the negative charging of CdSe QDs. In trions, excited states of single charged QDs, the additional electron in the conduction band speeds up the hot electron cooling by enhanced electron-electron scattering followed by charge... (More)

Fulfilling the potential of colloidal semiconductor quantum dots (QDs) in electrically driven applications remains a challenge largely since operation of such devices involves charged QDs with drastically different photophysical properties compared to their well-studied neutral counterparts. In this work, the full picture of excited state dynamics in charged CdSe QDs at various time scales has been revealed via transient absorption spectroscopy combined with electrochemistry as a direct manipulation tool to control the negative charging of CdSe QDs. In trions, excited states of single charged QDs, the additional electron in the conduction band speeds up the hot electron cooling by enhanced electron-electron scattering followed by charge redistribution and polaron formation in a picosecond time scale. The trions are finally decayed by the Auger process in a 500 ps time scale. Double charging in QDs, on the other hand, decelerates the polaron formation process while accelerates the following Auger decay. Our work demonstrates the potential of photoelectrochemistry as a platform for ultrafast spectroscopy of charged species and paves the way for further studies to develop comprehensive knowledge of the photophysical processes in charged QDs more than the well-known Auger decay, facilitating their use in future optoelectronic applications.

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type
Contribution to journal
publication status
published
subject
keywords
Auger decay, Double charged, Optoelectronics, Polaron, Semiconductor nanocrystals, Single charged, Solar cells, Spectroelectrochemistry, Tetron, Transient absorption spectroscopy
in
ACS Applied Energy Materials
volume
3
issue
12
pages
12525 - 12531
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85097906641
ISSN
2574-0962
DOI
10.1021/acsaem.0c02478
language
English
LU publication?
yes
id
a11a5095-f4e2-4f69-a325-abb72c889c77
date added to LUP
2021-01-11 09:39:43
date last changed
2021-01-12 01:40:40
@article{a11a5095-f4e2-4f69-a325-abb72c889c77,
  abstract     = {<p>Fulfilling the potential of colloidal semiconductor quantum dots (QDs) in electrically driven applications remains a challenge largely since operation of such devices involves charged QDs with drastically different photophysical properties compared to their well-studied neutral counterparts. In this work, the full picture of excited state dynamics in charged CdSe QDs at various time scales has been revealed via transient absorption spectroscopy combined with electrochemistry as a direct manipulation tool to control the negative charging of CdSe QDs. In trions, excited states of single charged QDs, the additional electron in the conduction band speeds up the hot electron cooling by enhanced electron-electron scattering followed by charge redistribution and polaron formation in a picosecond time scale. The trions are finally decayed by the Auger process in a 500 ps time scale. Double charging in QDs, on the other hand, decelerates the polaron formation process while accelerates the following Auger decay. Our work demonstrates the potential of photoelectrochemistry as a platform for ultrafast spectroscopy of charged species and paves the way for further studies to develop comprehensive knowledge of the photophysical processes in charged QDs more than the well-known Auger decay, facilitating their use in future optoelectronic applications.</p>},
  author       = {Honarfar, Alireza and Mourad, Hassan and Lin, Weihua and Polukeev, Alexey and Rahaman, Ahibur and Abdellah, Mohamed and Chábera, Pavel and Pankratova, Galina and Gorton, Lo and Zheng, Kaibo and Pullerits, Tönu},
  issn         = {2574-0962},
  language     = {eng},
  number       = {12},
  pages        = {12525--12531},
  publisher    = {The American Chemical Society (ACS)},
  series       = {ACS Applied Energy Materials},
  title        = {Photoexcitation dynamics in electrochemically charged CdSe quantum dots : From hot carrier cooling to auger recombination of negative trions},
  url          = {http://dx.doi.org/10.1021/acsaem.0c02478},
  doi          = {10.1021/acsaem.0c02478},
  volume       = {3},
  year         = {2020},
}