Issue 38, 2011

Photoinduced hole trapping in single semiconductor quantum dots at specific sites at silicon oxide interfaces

Abstract

Blinking dynamics of CdSe/ZnS semiconductor quantum dots (QD) are characterized by (truncated) power law distributions exhibiting a wide dynamic range in probability densities and time scales both for off- and on-times. QDs were immobilized on silicon oxide surfaces with varying grades of hydroxylation and silanol group densities, respectively. While the off-time distributions remain unaffected by changing the surface properties of the silicon oxide, a deviation from the power law dependence is observed in the case of on-times. This deviation can be described by a superimposed single exponential function and depends critically on the local silanol group density. Furthermore, QDs in close proximity to silanol groups exhibit both high average photoluminescence intensities and large on-time fractions. The effect is attributed to an interaction between the QDs and the silanol groups which creates new or deepens already existing hole trap states within the ZnS shell. This interpretation is consistent with the trapping model introduced by Verberk et al. (R. Verberk, A. M. van Oijen and M. Orrit, Phys. Rev. B, 2002, 66, 233202).

Graphical abstract: Photoinduced hole trapping in single semiconductor quantum dots at specific sites at silicon oxide interfaces

Article information

Article type
Paper
Submitted
22 Jun 2011
Accepted
28 Jul 2011
First published
22 Aug 2011

Phys. Chem. Chem. Phys., 2011,13, 17084-17092

Photoinduced hole trapping in single semiconductor quantum dots at specific sites at silicon oxide interfaces

C. Krasselt, J. Schuster and C. von Borczyskowski, Phys. Chem. Chem. Phys., 2011, 13, 17084 DOI: 10.1039/C1CP22040C

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