Interplay between optical gain and photoinduced absorption in CdSe nanocrystals

A. V. Malko, A. A. Mikhailovsky, M. A. Petruska, J. A. Hollingsworth, V. I. Klimov

Research output: Contribution to journalArticle

83 Citations (Scopus)

Abstract

A potential complication associated with the realization of the optical-gain regime in semiconductor nanocrystals (NCs) arises from the competing phenomenon of excited-state absorption. Here, we apply an ultrafast transient absorption technique to study the competition between optical gain and excited-state (photoinduced) absorption in CdSe NCs as a function of NC size, surface passivation, and solvent/matrix identity. We observe that for NCs prepared in such a commonly used solvent as hexane, the contribution from photoinduced absorption rapidly increases with decreasing NC radius, and it completely suppresses optical gain in NCs of small sizes. Further, the magnitude of photoinduced absorption is sensitive both to the type and the quality of surface passivation, as well as to the identity of the solvent/matrix material. These observations, along with a strong size dependence, indicate that photoinduced absorption interfering with optical gain is not intrinsic to CdSe NCs but, instead, results from the involvement of NC interface states/processes.

Original languageEnglish
Pages (from-to)5250-5255
Number of pages6
JournalJournal of Physical Chemistry B
Volume108
Issue number17
DOIs
Publication statusPublished - Apr 29 2004

ASJC Scopus subject areas

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

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