Charge carrier resolved relaxation of the first excitonic state in CdSe quantum dots probed with near-infrared transient absorption spectroscopy

Eric A. McArthur, Adam J. Morris-Cohen, Kathryn E. Knowles, Emily A Weiss

Research output: Contribution to journalArticle

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Abstract

This manuscript describes a global regression analysis of near-infrared (NIR, 900-1300 nm) transient absorptions (TA) of colloidal CdSe quantum dots (QDs) photoexcited to their first (1Se1S3/2) excitonic state. Near-IR TA spectroscopy facilitates charge carrier-resolved analysis of excitonic decay of QDs because signals in the NIR are due exclusively to absorptions of photoexcited electrons and holes, as probe energies in this region are not high enough to induce absorptions across the optical bandgap that crowd the visible TA spectra. The response of each observed component of the excitonic decay to the presence of a hole-trapping ligand (1-octanethiol) and an electron-accepting ligand (1,4-benzoquinone), and comparison of time constants to those for recovery of the ground state bleaching feature in the visible TA spectrum, allow for the assignment of the components to (i) a 1.6 ps hole trapping process, (ii) 19 ps and 274 ps surface-mediated electron trapping processes, and (iii) a ∼5 ns recombination of untrapped electrons.

Original languageEnglish
Pages (from-to)14514-14520
Number of pages7
JournalJournal of Physical Chemistry B
Volume114
Issue number45
DOIs
Publication statusPublished - Dec 8 2010

Fingerprint

Charge carriers
Absorption spectroscopy
Semiconductor quantum dots
charge carriers
absorption spectroscopy
quantum dots
Infrared radiation
Electrons
trapping
Absorption spectra
electrons
Ligands
absorption spectra
ligands
Optical band gaps
quinones
decay
bleaching
Bleaching
Regression analysis

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Materials Chemistry
  • Surfaces, Coatings and Films

Cite this

Charge carrier resolved relaxation of the first excitonic state in CdSe quantum dots probed with near-infrared transient absorption spectroscopy. / McArthur, Eric A.; Morris-Cohen, Adam J.; Knowles, Kathryn E.; Weiss, Emily A.

In: Journal of Physical Chemistry B, Vol. 114, No. 45, 08.12.2010, p. 14514-14520.

Research output: Contribution to journalArticle

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