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

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DOIResolve DOI: http://doi.org/10.1021/jz401896k
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TypeArticle
Journal titleThe Journal of Physical Chemistry Letters
ISSN1948-7185
Volume4
Issue21
Pages38063812; # of pages: 7
SubjectExcitation power; Exciton dynamics; Meta-stable state; Silicon nanocrystals; Silicon nanoparticles; State-filling; Transient absorption spectroscopies; Ultra-fast dynamics; Excited states; Optical waveguides; Excitons
AbstractThe 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. © 2013 American Chemical Society.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); Security and Disruptive Technologies
Peer reviewedYes
NPARC number21271813
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Record identifier7dbcb73a-4507-4d08-962e-b3f73d77a0fa
Record created2014-04-22
Record modified2017-03-23
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