Atomistic Design of CdSe/CdS Core-Shell Quantum Dots with Suppressed Auger Recombination

Ankit Jain, Oleksandr Voznyy, Sjoerd Hoogland, Marek Korkusinski, Pawel Hawrylak, Edward H. Sargent*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

We design quasi-type-II CdSe/CdS core-shell colloidal quantum dots (CQDs) exhibiting a suppressed Auger recombination rate. We do so using fully atomistic tight-binding wave functions and microscopic Coulomb interactions. The recombination rate as a function of the core and shell size and shape is tested against experiments. Because of a higher density of deep hole states and stronger hole confinement, Auger recombination is found to be up to six times faster for positive trions compared to negative ones in 4 nm core/10 nm shell CQDs. Soft-confinement at the interface results in weak suppression of Auger recombination compared to same-bandgap sharp-interface CQDs. We find that the suppression is due to increased volume of the core resulting in delocalization of the wave functions, rather than due to soft-confinement itself. We show that our results are consistent with previous effective mass models with the same system parameters. Increasing the dot volume remains the most efficient way to suppress Auger recombination. We predict that a 4-fold suppression of Auger recombination can be achieved in 10 nm CQDs by increasing the core volume by using rodlike cores embedded in thick shells.

Original languageEnglish (US)
Pages (from-to)6491-6496
Number of pages6
JournalNano letters
Volume16
Issue number10
DOIs
StatePublished - Oct 12 2016

Keywords

  • Atomistic simulations
  • Auger recombination
  • CdSe/CdS
  • Core-shell quantum dots
  • Interface grading
  • Tight-binding

ASJC Scopus subject areas

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering

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