Biexciton Binding Energy and Line width of Single Quantum Dots at Room Temperature

Biexciton Binding Energy and Line width of Single Quantum Dots at Room Temperature

Vonk, Sander J.W. (Debye Institute)
Heemskerk, Bart A.J. (Debye Institute)
Keitel, Robert C. (ETH Zürich)
Hinterding, Stijn O.M. (Debye Institute)
Geuchies, J.J. (TU Delft ChemE/Opto-electronic Materials)
Houtepen, A.J. (TU Delft ChemE/Opto-electronic Materials)
Rabouw, Freddy T. (Debye Institute)

2021

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 (Eb = 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.

biexciton line width
multiexciton emission
quantum dots
single-quantum-dot spectroscopy

http://resolver.tudelft.nl/uuid:710aac60-3681-4085-a0e4-9d618660d67e

https://doi.org/10.1021/acs.nanolett.1c01556

1530-6984

Nano Letters: a journal dedicated to nanoscience and nanotechnology, 21 (13), 5760-5766

Institutional Repository

journal article

© 2021 Sander J.W. Vonk, Bart A.J. Heemskerk, Robert C. Keitel, Stijn O.M. Hinterding, J.J. Geuchies, A.J. Houtepen, Freddy T. Rabouw