| Autor: |
Vonk SJW; Debye Institute, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands., Heemskerk BAJ; Debye Institute, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands., Keitel RC; Optical Materials Engineering Laboratory, ETH Zurich, Leonhardstrasse 21, 8092 Zurich, Switzerland., Hinterding SOM; Debye Institute, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands., Geuchies JJ; Optoelectronic Materials Section, Faculty of Applied Sciences, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, The Netherlands., Houtepen AJ; Optoelectronic Materials Section, Faculty of Applied Sciences, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, The Netherlands., Rabouw FT; Debye Institute, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands. |
| Abstrakt: |
Broadening of multiexciton emission from colloidal quantum dots (QDs) at room temperature is important for their use in high-power applications, but an in-depth characterization has not been possible until now. We present and apply a novel spectroscopic method to quantify the biexciton line width and biexciton binding energy of single CdSe/CdS/ZnS colloidal QDs at room temperature. In our method, which we term "cascade spectroscopy", we select emission events from the biexciton cascade and reconstruct their spectrum. The biexciton has an average emission line width of 86 meV on the single-QD scale, similar to that of the exciton. Variations in the biexciton repulsion ( E b = 4.0 ± 3.1 meV; mean ± standard deviation of 15 QDs) are correlated with but are more narrowly distributed than variations in the exciton energy (10.0 meV standard deviation). Using a simple quantum-mechanical model, we conclude that inhomogeneous broadening in our sample is primarily due to variations in the CdS shell thickness. |
