期刊
NANO LETTERS
卷 16, 期 10, 页码 6491-6496出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.6b03059
关键词
Auger recombination; atomistic simulations; core-shell quantum dots; interface grading tight-binding; CdSe/CdS
类别
资金
- Natural Sciences and Engineering Research Council (NSERC) of Canada
- Ontario Research Fund Research Excellence Program
- IBM Canada Research and Development Center
- IBM Canada Research and Development Center through Southern Ontario Smart Computing Innovation Platform (SOSCIP) postdoctoral fellowship
- Ontario Government
- Federal Economic Development Agency for Southern Ontario
- Canada Foundation for Innovation of Compute Canada
- Government of Ontario
- Ontario Research Fund - Research Excellence
- University of Toronto
- University of Ottawa Research Chair in Quantum Theory of Materials, Nanostructures and Devices
We design quasi-type-II CdSe/CdS core-shell colloidal quantum dots (CQDs) exhibiting a suppressed Auger recombination rate. We do so using fully atomistic tight-binding wave functions and microscopic Coulomb interactions. The recombination rate as a function of the core and shell size and shape is tested against experiments. Because of a higher density of deep hole states and stronger hole confinement, Auger recombination is found to be up to six times faster for positive trions compared to negative ones in 4 nm core/10 nm shell CQDs. Soft-confinement at the interface results in weak suppression of Auger recombination compared to same-bandgap sharp-interface CQDs. We find that the suppression is due to increased volume of the core resulting in delocalization of the wave functions, rather than due to soft-confinement itself. We show that our results are consistent with previous effective mass models with the same system parameters. Increasing the dot volume remains the most efficient way to suppress Auger recombination. We predict that a 4-fold suppression of Auger recombination can be achieved in 10 nm CQDs by increasing the core volume by using rodlike cores embedded in thick shells.
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