title: Carrier relaxation dynamics in lead sulfide colloidal quantum dots.
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 x 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.
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, Canada. e.istrate@utoronto.ca
authors.forename: Emanuel
authors.initials: E
authors.lastname: Istrate
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Hoogland
authors.forename: Vlad
authors.initials: V
authors.lastname: Sukhovatkin
authors.forename: Larissa
authors.initials: L
authors.lastname: Levina
authors.forename: Stefan
authors.initials: S
authors.lastname: Myrskog
authors.forename: Peter W E
authors.initials: PW
authors.lastname: Smith
authors.forename: Edward H
authors.initials: EH
authors.lastname: Sargent