Time-resolved intraband relaxation of strongly confined electrons and holes in colloidal PbSe nanocrystals

Jeffrey M. Harbold, Hui Du, Todd D. Krauss, Kyung-Sang Cho, Chris B. Murray, and Frank W. Wise
Phys. Rev. B 72, 195312 – Published 8 November 2005

Abstract

The relaxation of strongly confined electrons and holes from higher excited states to their lowest excited states in colloidal PbSe nanocrystals has been time resolved using femtosecond transient absorption spectroscopy. In contrast to II-VI and III-V semiconductor nanocrystals, both electrons and holes are strongly confined in PbSe nanocrystals. Despite the large electron and hole energy level spacings (at least 12 times the optical phonon energy), we consistently observe picosecond time-scale relaxation. Existing theories of carrier relaxation cannot account for these experimental results. We conjecture about mechanisms that could circumvent the expected phonon bottleneck in IV-VI quantum dots.

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  • Received 5 December 2004

DOI:https://doi.org/10.1103/PhysRevB.72.195312

©2005 American Physical Society

Authors & Affiliations

Jeffrey M. Harbold1, Hui Du2, Todd D. Krauss2, Kyung-Sang Cho3, Chris B. Murray3, and Frank W. Wise1

  • 1Department of Applied Physics, Cornell University, Ithaca, New York 14853, USA
  • 2Department of Chemistry, University of Rochester, Rochester, New York 14627, USA
  • 3IBM, T. J. Watson Research Center, Yorktown Heights, New York 10598, USA

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Issue

Vol. 72, Iss. 19 — 15 November 2005

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