Califano, M. (2008) Efficient Auger electron cooling in seemingly unfavourable configurations: hole traps and electrochemical charging. The Journal of Physical Chemistry C, 112 (23). pp. 8570-8574.
Full text not available from this repository. (Request a copy)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 photogen- erated 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 have 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., hole-less) CdSe nanocrystals leads to short p electron lifetimes comparable to those calculated in the presence of a photogenerated hole delocalised in the dot core. Furthermore, it is shown that efficient energy transfer can also be achieved between a delocalised electron and a surface-trapped hole leading to short p electron lifetimes in the (sub-) ps range. These results are in quantitative agreement with experiment and consistent with the Auger interpretation of the electron relaxation. The fast sub-ps electron relaxation times calculated in the presence of a hole localised in a shallow surface trap raise the intriguing question of whether in earlier measurements in TOPO-capped nanocrystals the hole was indeed delocalised within the dot core, as it was believed at the time, or whether it could have been in a trap state.
| Item Type: | Article |
|---|---|
| Academic Units: | The University of Leeds > Faculty of Engineering (Leeds) > School of Electronic & Electrical Engineering (Leeds) > Institute of Microwaves and Photonics (Leeds) |
| Depositing User: | Sherpa Assistant |
| Date Deposited: | 15 Aug 2008 13:09 |
| Last Modified: | 29 Sep 2010 14:21 |
| Published Version: | http://dx.doi.org/10.1021/jp7104743 |
| Status: | Published |
| Publisher: | American Chemical Society |
| Identification Number: | 10.1021/jp7104743 |
| URI: | http://eprints.whiterose.ac.uk/id/eprint/4330 |
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