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Issue 39, 2012
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Ultrafast exciton dynamics in Type II ZnTe–ZnSe colloidal quantum dots

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Abstract

Ultrafast transient absorption spectroscopy is used to investigate the exciton dynamics of Type II ZnTe–ZnSe core–shell colloidal quantum dots. Surface-trapping is shown to occur within a few picosecond for hot electrons and with a few 10s of picoseconds for electrons cooled to the band-edge, and is the dominant process in the decay of the band-edge bleach for well-stirred samples pumped at moderate powers. The surface-trapped electrons produce a broad photo-induced absorption that spectrally overlaps with the band-edge, distorting and partially cancelling out the bleach feature. At high pump powers and for unstirred samples, these surface-trapped electrons can survive sufficiently long within the pumped volume to accumulate under repeated excitation of the sample, resulting in the formation of an additional exciton decay channel.

Graphical abstract: Ultrafast exciton dynamics in Type II ZnTe–ZnSe colloidal quantum dots

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Publication details

The article was received on 13 Jun 2012, accepted on 21 Aug 2012 and first published on 21 Aug 2012


Article type: Paper
DOI: 10.1039/C2CP41978E
Citation: Phys. Chem. Chem. Phys., 2012,14, 13638-13645
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    Ultrafast exciton dynamics in Type II ZnTe–ZnSe colloidal quantum dots

    M. Cadirci, S. K. Stubbs, S. M. Fairclough, E. J. Tyrrell, A. A. R. Watt, J. M. Smith and D. J. Binks, Phys. Chem. Chem. Phys., 2012, 14, 13638
    DOI: 10.1039/C2CP41978E

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