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Califano, M (2008) Efficient Auger electron cooling in seemingly unfavourable configurations: hole traps and electrochemical charging. Journal of Physical Chemistry C, 112 (23). 8570 - 8574. ISSN 1932-7447
Abstract
The absence of a phonon bottleneck in the intraband relaxation between p-like and s-like electron states in CdSe nanocrystals is generally ascribed to efficient inelastic scattering with the photogenerated hole (Auger cooling). However, the fast relaxation of electrons observed in the absence of a hole or in the presence of a hole trapped in a surface state has raised serious questions about the suitability of this model. The semiempirical pseudopotential calculations reported here show that electron−electron scattering in chemically reduced or electrochemically charged (i.e., holeless) CdSe nanocrystals leads to short p electron lifetimes comparable to those calculated in the presence of a photogenerated hole delocalized in the dot core. Furthermore, it is shown that efficient energy transfer can also be achieved between a delocalized electron and a surface-trapped hole, leading to short p electron lifetimes in the (sub-) picosecond range. These results are in quantitative agreement with experiment and are consistent with the Auger interpretation of the electron relaxation. The fast sub-picosecond electron relaxation times calculated in the presence of a hole localized in a shallow surface trap raise the intriguing question of whether in earlier measurements in TOPO-capped nanocrystals the hole was indeed delocalized within the dot core, as it was believed at the time, or whether it could have been in a trap state.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Keywords: | Surface states; Auger processes; electron relaxation; semiconductor nanocrystals |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Electronic & Electrical Engineering (Leeds) > Pollard Institute (Leeds) |
Depositing User: | Sherpa Assistant |
Date Deposited: | 26 Mar 2015 14:11 |
Last Modified: | 29 Mar 2018 05:12 |
Published Version: | http://dx.doi.org/10.1021/jp7104743 |
Status: | Published |
Publisher: | American Chemical Society |
Identification Number: | 10.1021/jp7104743 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:75637 |
Available Versions of this Item
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Efficient Auger electron cooling in seemingly unfavourable configurations: hole traps and electrochemical charging. (deposited 15 Aug 2008 13:09)
- Efficient Auger electron cooling in seemingly unfavourable configurations: hole traps and electrochemical charging. (deposited 26 Mar 2015 14:11) [Currently Displayed]