Effect of the core/shell interface on auger recombination evaluated by single-quantum-dot spectroscopy

Young Shin Park, Wan Ki Bae, Lazaro A. Padilha, Jeffrey M. Pietryga, Victor I Klimov

Research output: Contribution to journalArticle

103 Citations (Scopus)

Abstract

Previous single-particle spectroscopic studies of colloidal quantum dots have indicated a significant spread in biexciton lifetimes across an ensemble of nominally identical nanocrystals. It has been speculated that in addition to dot-to-dot variation in physical dimensions, this spread is contributed to by variations in the structure of the quantum dot interface, which controls the shape of the confinement potential. Here, we directly evaluate the effect of the composition of the core-shell interface on single- and multiexciton dynamics via side-by-side measurements of individual core-shell CdSe/CdS nanocrystals with a sharp versus smooth (graded) interface. To realize the latter type of structures we incorporate a CdSexS1-x alloy layer of controlled composition and thickness between the CdSe core and the CdS shell. We observe that while having essentially no effect on single-exciton decay, the interfacial alloy layer leads to a systematic increase in biexciton lifetimes, which correlates with the increase in the biexciton emission efficiency, as inferred from two-photon correlation measurements. These observations provide direct experimental evidence that in addition to the size of the quantum dot, its interfacial properties also significantly affect the rate of Auger recombination, which governs biexciton decay. These findings help rationalize previous observations of a significant heterogeneity in the biexciton lifetimes across similarly sized quantum dots and should facilitate the development of "Auger-recombination-free" colloidal nanostructures for a range of applications from lasers and light-emitting diodes to photodetectors and solar cells.

Original languageEnglish
Pages (from-to)396-402
Number of pages7
JournalNano Letters
Volume14
Issue number2
DOIs
Publication statusPublished - Feb 12 2014

Fingerprint

Semiconductor quantum dots
quantum dots
Spectroscopy
life (durability)
Nanocrystals
spectroscopy
nanocrystals
decay
Photodetectors
Chemical analysis
Excitons
Light emitting diodes
photometers
Nanostructures
Solar cells
light emitting diodes
Photons
solar cells
excitons
Lasers

Keywords

  • alloyed interface
  • Auger recombination
  • biexciton
  • core/shell
  • quantum dot
  • second-order intensity correlation function
  • Semiconductor nanocrystal

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Mechanical Engineering

Cite this

Effect of the core/shell interface on auger recombination evaluated by single-quantum-dot spectroscopy. / Park, Young Shin; Bae, Wan Ki; Padilha, Lazaro A.; Pietryga, Jeffrey M.; Klimov, Victor I.

In: Nano Letters, Vol. 14, No. 2, 12.02.2014, p. 396-402.

Research output: Contribution to journalArticle

Park, Young Shin ; Bae, Wan Ki ; Padilha, Lazaro A. ; Pietryga, Jeffrey M. ; Klimov, Victor I. / Effect of the core/shell interface on auger recombination evaluated by single-quantum-dot spectroscopy. In: Nano Letters. 2014 ; Vol. 14, No. 2. pp. 396-402.
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