Biexciton Binding Energy and Line width of Single Quantum Dots at Room Temperature
Abstract
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. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000497931Publication status
publishedExternal links
Journal / series
Nano LettersVolume
Pages / Article No.
Publisher
American Chemical SocietySubject
quantum dots; snigle-quantum-dot spectroscopy; multiexciton emission; biexciton line widthFunding
339905 - Quantum-Dot Plasmonics and Spasers (EC)
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