Ultrafast exciton dynamics in Type II ZnTe-ZnSe colloidal quantum dots.

Journal article

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.

Authors: Cadirci, M; Stubbs, S; Fairclough, S; Tyrrell, E; Watt, A

• Publication status: Published
• Journal: Physical chemistry chemical physics : PCCP
• Volume: 14
• Issue: 39
• Pages: 13638-13645
• Publication date: 2012-10-01
• DOI: 10.1039/c2cp41978e
• EISSN: 1463-9084
• ISSN: 1463-9076
• Language: English