J. Phys. Chem. B, 112 (10), 2757 -2760, 2008. 10.1021/jp076809g S1520-6106(07)06809-5
Web Release Date: February 15, 2008

Copyright © 2008 American Chemical Society

Carrier Relaxation Dynamics in Lead Sulfide Colloidal Quantum Dots

Emanuel Istrate,* Sjoerd Hoogland, Vlad Sukhovatkin, Larissa Levina, Stefan Myrskog, Peter W. E. Smith, and Edward H. Sargent

Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada

Received: August 24, 2007

In Final Form: December 17, 2007

Abstract:

We report transient absorption saturation measurements on lead sulfide colloidal nanocrystals at the first and second exciton energies and fit the results to a model incorporating intraband and interband relaxation processes. We study in detail the Auger recombination from the first excited state, which takes place when more than one electron-hole pair is excited in a dot. We find an Auger coefficient of 4.5 × 10-30 cm6/s for dots of 5.5 nm diameter, and observe saturation of the absorption bleaching when the (8-fold degenerate) first level is filled. We develop a model for the absorption dynamics using Poisson statistics and find a good fit with our experimental measurements.

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