Issue 43, 2012

Ultrafast exciton dynamics in InAs/ZnSe nanocrystal quantum dots

Abstract

Colloidal nanocrystal quantum dots with a band gap in the near infra-red have potential application as the emitters for telecommunications or in vivo imaging, or as the photo-absorbing species in next generation solar cells or photodetectors. However, electro- and photoluminescence yields and the efficiency with which photo-generated charges can be extracted from quantum dots depend on the total rate of recombination, which can be dominated by surface-mediated processes. In this study, we use ultrafast transient absorption spectroscopy to characterise the recombination dynamics of photo-generated charges in InAs/ZnSe nanocrystal quantum dots. We find that recombination is dominated by rapid, sub-nanosecond transfer of conduction band electrons to surface states. For the size of dots studied, we also find no evidence of significant multiple exciton generation for photon energies up to 3.2 times the band gap, in agreement with our theoretical modelling.

Graphical abstract: Ultrafast exciton dynamics in InAs/ZnSe nanocrystal quantum dots

Supplementary files

Article information

Article type
Paper
Submitted
25 Jun 2012
Accepted
22 Aug 2012
First published
30 Aug 2012

Phys. Chem. Chem. Phys., 2012,14, 15166-15172

Ultrafast exciton dynamics in InAs/ZnSe nanocrystal quantum dots

M. Cadirci, S. K. Stubbs, S. J. O. Hardman, O. Masala, G. Allan, C. Delerue, N. Pickett and D. J. Binks, Phys. Chem. Chem. Phys., 2012, 14, 15166 DOI: 10.1039/C2CP42125A

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