A multi-timescale map of radiative and nonradiative decay pathways for excitons in CdSe quantum dots

Kathryn E. Knowles, Eric A. McArthur, Emily A. Weiss

Research output: Contribution to journalArticle

135 Citations (Scopus)

Abstract

A combination of transient absorption (TA) and time-resolved photoluminescence (TRPL) spectroscopies performed on solution-phase samples of colloidal CdSe quantum dots (QDs) allows the construction of a time-resolved, charge carrier-resolved map of decay from the first excitonic state of the QD. Data from TA and TRPL yield the same six exponential components, with time constants ranging from ∼1 ps to 50 ns, for excitonic decay. Comparison of TA signals in the visible and near-infrared (NIR) spectral regions enables determination of the relative contributions of electron and hole dynamics to each decay component, and comparison of TA and TRPL reveals that each component represents a competition between radiative and nonradiative decay pathways. In total, these data suggest that the QD sample comprises at least three distinct populations that differ in both the radiative and nonradiative decay pathways available to the excitonic charge carriers, and provide evidence for multiple emissive excitonic states in which the hole is not in the valence band, but rather a relaxed or trapped state.

Original languageEnglish
Pages (from-to)2026-2035
Number of pages10
JournalACS nano
Volume5
Issue number3
DOIs
Publication statusPublished - Mar 22 2011

Keywords

  • charge carrier trapping
  • photoluminescence upconversion
  • quantum dot
  • radiative recombination
  • time-correlated single photon counting
  • transient absorption

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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