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Title: Quantum Yield Heterogeneity among Single Nonblinking Quantum Dots Revealed by Atomic Structure-Quantum Optics Correlation

Journal Article · · ACS Nano
 [1];  [1];  [2];  [2];  [1];  [1];  [2];  [2];  [3]
  1. Vanderbilt Univ., Nashville, TN (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Vanderbilt Univ., Nashville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Physical variations in colloidal nanostructures give rise to heterogeneity in expressed optical behavior. This correlation between nanoscale structure and function demands interrogation of both atomic structure and photophysics at the level of single nanostructures to be fully understood. Herein, by conducting detailed analyses of fine atomic structure, chemical composition, and time-resolved single-photon photoluminescence data for the same individual nanocrystals, we reveal inhomogeneity in the quantum yields of single nonblinking "giant" CdSe/CdS core/shell quantum dots (g-QDs). We find that each g-QD possesses distinctive single exciton and biexciton quantum yields that result mainly from variations in the degree of charging, rather than from volume or structure inhomogeneity. We further establish that there is a very limited nonemissive "dark" fraction (<2%) among the studied g-QDs and present direct evidence that the g-QD core must lack inorganic passivation for the g-QD to be "dark". Although, in contrast to conventional QDs, ensemble photoluminescence quantum yield is principally defined by charging processes rather than the existence of dark g-QDs.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
DOE Contract Number:
AC05-00OR22725
OSTI ID:
1393884
Journal Information:
ACS Nano, Vol. 10, Issue 2; ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English

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Correlating nano black spots and optical stability in mixed halide perovskite quantum dots journal January 2018
Excited-State Dynamics in Colloidal Semiconductor Nanocrystals journal August 2016
Determination of quantum yields of semiconductor nanocrystals at the single emitter level via fluorescence correlation spectroscopy journal January 2018
Real colloidal quantum dot structures revealed by high resolution analytical electron microscopy journal October 2019
Strong plasmonic enhancement of biexciton emission: controlled coupling of a single quantum dot to a gold nanocone antenna preprint January 2016
Strong plasmonic enhancement of biexciton emission: controlled coupling of a single quantum dot to a gold nanocone antenna journal February 2017
Excited-State Dynamics in Colloidal Semiconductor Nanocrystals book August 2016
Effects of interface-potential smoothness and wavefunction delocalization on Auger recombination in colloidal CdSe-based core/shell quantum dots journal December 2019