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Photoluminescence of colloidal CdSe/ZnS quantum dots: the critical effect of water

Photoluminescence of colloidal CdSe/ZnS quantum dots: the critical effect of water
Photoluminescence of colloidal CdSe/ZnS quantum dots: the critical effect of water
An investigation of the photoinduced fluorescence enhancement (PFE) behavior of CdSe/ZnS core/shell quantum dots deposited at low densities, under anhydrous and controlled water humidity, under oxygen or argon, is presented. The photoluminescence properties of CdSe/ZnS QDs are highly dependent upon the local gaseous environment. Under anhydrous conditions, under either oxygen or argon, there was no observed PFE, even though there were remarkable differences in the photoluminescence spectra. Under argon, (i) the initial photoluminescence properties are independent of humidity level; however, (ii) the PFE effect observed is highly dependent on the environmental humidity levels. Under oxygen, (i) the initial photoluminescence properties (spectra and yield) are dependent on humidity levels and (ii) the PFE effect observed is highly dependent on the humidity levels. Comparing D2O versus H2O humidity level effects on the photoluminescence properties of CdSe/ZnS QDs provides evidence for a water-molecule-stabilized state that facilitates luminescence processes. The products of CdSe/ZnS QDs exposed under a humid oxygen environment were evaluated by X-ray photoelectron spectroscopy. Oxidation of both the CdSe core and the ZnS shell was established. Oxidation of the ZnS shell is suggested to be a result of reaction with peroxide products resulting from the oxygen radical anion. These results highlight the important sensitivity of QDs to water and prove the existence of competing electronic and chemical effects on different time scales.
1932-7447
12069-12077
Pechstedt, Katrin
8fcd400c-c54d-49d3-bd5b-7dd4cf32f140
Whittle, Tracy
fbcbf262-7884-4430-936a-67c70ee26b7e
Baumberg, Jeremy J.
51423b5f-bdb8-4851-8d50-472253ceb12c
Melvin, Tracy
fd87f5eb-2bb9-48fa-b7be-7100ace9c50f
Pechstedt, Katrin
8fcd400c-c54d-49d3-bd5b-7dd4cf32f140
Whittle, Tracy
fbcbf262-7884-4430-936a-67c70ee26b7e
Baumberg, Jeremy J.
51423b5f-bdb8-4851-8d50-472253ceb12c
Melvin, Tracy
fd87f5eb-2bb9-48fa-b7be-7100ace9c50f

Pechstedt, Katrin, Whittle, Tracy, Baumberg, Jeremy J. and Melvin, Tracy (2010) Photoluminescence of colloidal CdSe/ZnS quantum dots: the critical effect of water. The Journal of Physical Chemistry C, 114 (28), 12069-12077. (doi:10.1021/jp100415k).

Record type: Article

Abstract

An investigation of the photoinduced fluorescence enhancement (PFE) behavior of CdSe/ZnS core/shell quantum dots deposited at low densities, under anhydrous and controlled water humidity, under oxygen or argon, is presented. The photoluminescence properties of CdSe/ZnS QDs are highly dependent upon the local gaseous environment. Under anhydrous conditions, under either oxygen or argon, there was no observed PFE, even though there were remarkable differences in the photoluminescence spectra. Under argon, (i) the initial photoluminescence properties are independent of humidity level; however, (ii) the PFE effect observed is highly dependent on the environmental humidity levels. Under oxygen, (i) the initial photoluminescence properties (spectra and yield) are dependent on humidity levels and (ii) the PFE effect observed is highly dependent on the humidity levels. Comparing D2O versus H2O humidity level effects on the photoluminescence properties of CdSe/ZnS QDs provides evidence for a water-molecule-stabilized state that facilitates luminescence processes. The products of CdSe/ZnS QDs exposed under a humid oxygen environment were evaluated by X-ray photoelectron spectroscopy. Oxidation of both the CdSe core and the ZnS shell was established. Oxidation of the ZnS shell is suggested to be a result of reaction with peroxide products resulting from the oxygen radical anion. These results highlight the important sensitivity of QDs to water and prove the existence of competing electronic and chemical effects on different time scales.

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More information

Published date: 2010
Organisations: Optoelectronics Research Centre, Physics & Astronomy

Identifiers

Local EPrints ID: 177261
URI: https://eprints.soton.ac.uk/id/eprint/177261
ISSN: 1932-7447
PURE UUID: 0b902ee7-5eef-4ec2-bbf3-7bfd7cb26c06

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Date deposited: 16 Mar 2011 09:24
Last modified: 16 Jul 2019 23:45

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Contributors

Author: Katrin Pechstedt
Author: Tracy Whittle
Author: Jeremy J. Baumberg
Author: Tracy Melvin

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