Revealing the exciton fine structure of PbSe nanocrystal quantum dots using optical spectroscopy in high magnetic fields

Richard D Schaller, S. A. Crooker, D. A. Bussian, J. M. Pietryga, J. Joo, Victor I Klimov

Research output: Contribution to journalArticle

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Abstract

We measure the photoluminescence lifetime τ of excitons in colloidal PbSe nanocrystals (NCs) at low temperatures to 270 mK and in high magnetic fields to 15 T. For all NCs, τ increases sharply below 10 K but saturates by 500 mK. In contrast to the usual picture of well-separated "bright" and "dark" exciton states (found, e.g., in CdSe NCs), these dynamics fit remarkably well to a system having two exciton states with comparable-but small-oscillator strengths that are separated by only 300-900μeV depending on NC size. Importantly, magnetic fields reduce τ below 10 K, consistent with field-induced mixing between the two states. Magnetic-circular dichroism studies reveal exciton g factors from 2-5, and magnetophotoluminescence shows >10% circularly polarized emission.

Original languageEnglish
Article number067403
JournalPhysical Review Letters
Volume105
Issue number6
DOIs
Publication statusPublished - Aug 4 2010

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nanocrystals
fine structure
quantum dots
excitons
magnetic fields
spectroscopy
oscillator strengths
dichroism
photoluminescence
life (durability)

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Revealing the exciton fine structure of PbSe nanocrystal quantum dots using optical spectroscopy in high magnetic fields. / Schaller, Richard D; Crooker, S. A.; Bussian, D. A.; Pietryga, J. M.; Joo, J.; Klimov, Victor I.

In: Physical Review Letters, Vol. 105, No. 6, 067403, 04.08.2010.

Research output: Contribution to journalArticle

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