Red states versus blue states in colloidal silicon nanocrystals: Exciton sequestration into low-density traps

Jack Fuzell, Arthur Thibert, Tonya M. Atkins, Mita Dasog, Erik Busby, Jonathan G C Veinot, Susan M. Kauzlarich, Delmar S. Larsen

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

The ultrafast exciton photodynamics of red-emitting and blue-emitting colloidal Si nanocrystals are contrasted under low (1.5 mJ/cm2) and high (9.1 mJ/cm2) excitation powers with broadband transient absorption spectroscopy. While the low-power initiated transient signals differ strongly for the two samples, the high-power signals exhibit similar nonmonotonic kinetics, resulting in a new population formed on a 10 to 30-ps time scale with a sample independent spectrum and decay kinetics. This phenomenon is ascribed to the saturation of low-density red-emitting and blue-emitting traps via a state-filling mechanism to populate new meta-stable states at higher excitation powers. The states responsible for blue emission and high-power populations are ascribed to traps from low-density nitrogen and oxygen impurities, respectively, and share similar charge-transfer character with the silicon nanocrystal core.

Original languageEnglish (US)
Pages (from-to)3806-3812
Number of pages7
JournalJournal of Physical Chemistry Letters
Volume4
Issue number21
DOIs
StatePublished - Nov 7 2013

Keywords

  • exciton dynamics
  • silicon nanoparticles
  • state-filling
  • ultrafast dynamics

ASJC Scopus subject areas

  • Materials Science(all)

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