Biexciton Blinking in CdSe-Based Quantum Dots

Sander J.W. Vonk, Freddy T. Rabouw*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Experiments on single colloidal quantum dots (QDs) have revealed temporal fluctuations in the emission efficiency of the single-exciton state. These fluctuations, often termed “blinking”, are caused by opening/closing of charge-carrier traps and/or charging/discharging of the QD. In the regime of strong optical excitation, multiexciton states are formed. The emission efficiencies of multiexcitons are lower because of Auger processes, but a quantitative characterization is challenging. Here, we quantify fluctuations of the biexciton efficiency for single CdSe/CdS/ZnS core-shell QDs. We find that the biexciton efficiency “blinks” significantly. The additional electron due to charging of a QD accelerates Auger recombination by a factor of 2 compared to the neutral biexciton, while opening/closing of a charge-carrier trap leads to an increase of the nonradiative recombination rate by a factor of 4. To understand the fast rate of trap-assisted recombination, we propose a revised model for trap-assisted recombination based on reversible trapping. Finally, we discuss the implications of biexciton blinking for lasing applications.

Original languageEnglish
Pages (from-to)5353-5361
Number of pages9
JournalJournal of Physical Chemistry Letters
Volume14
Issue number23
DOIs
Publication statusPublished - 15 Jun 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society.

Funding

This work was supported by the Dutch Research Council NWO (OCENW.KLEIN.008 and Vi.Vidi.203.031) and by The Netherlands Center for Multiscale Catalytic Energy Conversion (MCEC), an NWO Gravitation Programme funded by the Ministry of Education, Culture and Science of the Government of The Netherland

FundersFunder number
Dutch Research Council NWOVi.Vidi.203.031, OCENW.KLEIN.008
MCEC
Ministry of Education, Culture and Science of the Government of The Netherland
Netherlands Center for Multiscale Catalytic Energy Conversion
Nederlandse Organisatie voor Wetenschappelijk Onderzoek

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