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

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

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


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.

Original languageEnglish
Pages (from-to)5760-5766
Number of pages7
JournalNano Letters
Issue number13
Publication statusPublished - 14 Jul 2021


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


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