Magneto-photoluminescence properties of colloidal CdSe nanocrystal aggregates

Daniel E. Blumling, Takahisa Tokumoto, Stephen McGill, Kenneth Knappenberger

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Magnetic fields up to 10 T were used to study the relative excited-state population of exciton fine-structure states in aggregates of 0-D CdSe nanocrystals. Following excitation by 400 nm light, energy-resolved, intensity-integrated photoluminescence (PL) spectra of CdSe quantum dot aggregates were collected at 1.6 K. Temperature-dependent PL measurements revealed multiple exciton relaxation channels, which were attributed to direct and longitudinal optical phonon-assisted recombination of isolated and aggregated nanocrystals. The relative populations of the 1S(e)- 1S3/2(h) exciton fine-structure levels in both isolated and aggregated nanocrystals were actively controlled by application of a magnetic field. The efficient applied magnetic field-assisted population control led to an increase in the total PL of the aggregate that resulted from a reduction in phonon-assisted recombination and an increase in direct radiative e-h recombination. An increase in the relative radiative recombination yield was attributed to field-induced mixing of the "dark" and "bright" exciton states. This behavior was quantified using a novel branching ratio analysis that related the relative population of the "bright" exciton to the total excited state population. The data present promise for studying spin-dependent energy transfer in nanocrystal superstructures.

Original languageEnglish (US)
Pages (from-to)14517-14525
Number of pages9
JournalJournal of Physical Chemistry C
Volume115
Issue number30
DOIs
StatePublished - Aug 4 2011

Fingerprint

Excitons
Nanocrystals
Photoluminescence
nanocrystals
excitons
photoluminescence
Magnetic fields
Excited states
fine structure
magnetic fields
excitation
radiative recombination
Energy transfer
Semiconductor quantum dots
energy transfer
quantum dots
LDS 751
Temperature
temperature
energy

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Cite this

Blumling, Daniel E. ; Tokumoto, Takahisa ; McGill, Stephen ; Knappenberger, Kenneth. / Magneto-photoluminescence properties of colloidal CdSe nanocrystal aggregates. In: Journal of Physical Chemistry C. 2011 ; Vol. 115, No. 30. pp. 14517-14525.
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Magneto-photoluminescence properties of colloidal CdSe nanocrystal aggregates. / Blumling, Daniel E.; Tokumoto, Takahisa; McGill, Stephen; Knappenberger, Kenneth.

In: Journal of Physical Chemistry C, Vol. 115, No. 30, 04.08.2011, p. 14517-14525.

Research output: Contribution to journalArticle

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