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Photoluminescence Properties of Core/Shell CdSe/ZnS Quantum Dots Encapsulated with Transparent layers for Third Generation Photovoltaics

Published online by Cambridge University Press:  16 August 2011

Bahareh Sadeghimakki ,
Navid Mohammad Sadeghi Jahed  and
Siva Sivoththaman
Bahareh Sadeghimakki
Affiliation:
Center for Advanced Photovoltaic Devices and Systems (CAPDS), Waterloo, ON N2L3G1 Canada Electrical and Computer Engineering Department, University of Waterloo, Waterloo, ON N2L3G1 Canada
Navid Mohammad Sadeghi Jahed
Affiliation:
Center for Advanced Photovoltaic Devices and Systems (CAPDS), Waterloo, ON N2L3G1 Canada Electrical and Computer Engineering Department, University of Waterloo, Waterloo, ON N2L3G1 Canada
Siva Sivoththaman
Affiliation:
Center for Advanced Photovoltaic Devices and Systems (CAPDS), Waterloo, ON N2L3G1 Canada Electrical and Computer Engineering Department, University of Waterloo, Waterloo, ON N2L3G1 Canada
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Abstract

In this work hydrophobicaly ligated cadmium selenide/zinc sulfide CdSe/ZnS quantum dots (QDs) were incorporated in transparent matrices by formation of CdSe/ZnS/SiO2 core/shell/shell structure using microemolsion synthesis method. The optical properties of the QDs encapsulated with a chemically grown oxide layers were studied. Intense luminescence properties of the QD/silica nanoparticles (NPs) were observed using steady state photoluminescence (PL) measurements. Confocal microscopy demonstrates fluorescence of the single core/shell/shell nanoparticles. The obtained results along with the Secondary Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) images provide information on the geometry of the QDs. The excitonic emission of nanoparticles was also mapped using a liquid nitrogen cryostat the 77K - 300K range. The temperature dependent PL spectra of the film demonstrate the temperature-dependent band gap shrinkage of the QDs. PL lifetime measurements were performed on the ensemble of NPs. Experimental data was fitted to the numerical model with lifetime constants in nanoseconds range. We demonstrate that the main nonradiative processes that limit the quantum yield (QY) of the QDs at room temperature are the carrier trapping at the interface of QD/silica and the exciton-phonon coupling. These studies give us insight to exploit the QD layers for photon down shifting and multiple exciton generation for application in photovoltaics.

Keywords

photoemissionnanoscalephotovoltaic
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1322: Symposium B – Third-Generation and Emerging Solar-Cell Technologies , 2011 , mrss11-1322-b02-02
Copyright
Copyright © Materials Research Society 2011

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References

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