Size-dependent oscillator strength and quantum efficiency of CdSe quantum dots controlled via the local density of states

M.D. Leistikow, Jeppe Johansen, A.J. Kettelarij, Peter Lodahl, W.L. Vos

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Abstract

We study experimentally time-resolved emission of colloidal CdSe quantum dots in an environment with a controlled local density of states LDOS. The decay rate is measured versus frequency and as a function of distance to a mirror. We observe a linear relation between the decay rate and the LDOS, allowing us to determine the size-dependent quantum efficiency and oscillator strength. We find that the quantum efficiency decreases with increasing emission energy mostly due to an increase in nonradiative decay. We manage to obtain the oscillator strength of the important class of CdSe quantum dots. The oscillator strength varies weakly with frequency in agreement with behavior of quantum dots in the strong confinement limit. Surprisingly, previously calculated tight-binding results differ by a factor of 5 with the measured absolute values. Results from pseudopotential calculations agree well with the measured radiative rates. Our results are relevant for applications of CdSe quantum dots in spontaneous emission control and cavity quantum electrodynamics.
Original languageEnglish
JournalPhysical Review B Condensed Matter
Volume79
Issue number4
Pages (from-to)045301
ISSN0163-1829
DOIs
Publication statusPublished - 2009

Bibliographical note

Copyright 2009 American Physical Society

Keywords

  • PHOTONIC CRYSTALS
  • INTERFACE
  • FLUORESCENCE
  • MICROCRYSTALS
  • POLARIZATION
  • SPONTANEOUS EMISSION
  • NANOCRYSTALS
  • ABSORPTION

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