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Energy exchange between optically excited Silicon Nanocrystals and Molecular Oxygen

Published online by Cambridge University Press:  01 February 2011

E. Gross ,
D. Kovalev ,
N. Künzner ,
J. Diener ,
F. Koch ,
V. Yu. Timoshenko  and
Minoru Fujii
E. Gross
Affiliation:
Technische Universität München, Physik Department E16, 85747 Garching, Germany
D. Kovalev
Affiliation:
Technische Universität München, Physik Department E16, 85747 Garching, Germany
N. Künzner
Affiliation:
Technische Universität München, Physik Department E16, 85747 Garching, Germany
J. Diener
Affiliation:
Technische Universität München, Physik Department E16, 85747 Garching, Germany
F. Koch
Affiliation:
Technische Universität München, Physik Department E16, 85747 Garching, Germany
V. Yu. Timoshenko
Affiliation:
Faculty of Physics, Moscow State M.V. Lomonosov University, 119992 Moscow, Russia
Minoru Fujii
Affiliation:
Department of Electrical and Electronics Engineering, Faculty of Engineering, Kobe University, Rokkodai, Nada, Kobe 657–28501, Japan
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Abstract

We report on the photosensitizing properties of optically excited Silicon (Si) nanocrystal assemblies that are employed for an efficient generation of singlet oxygen. Spin triplet state excitons confined in Si nanocrystals transfer their energy to molecular oxygen (MO) adsorbed on the nanocrystal surface. This process results in a strong suppression of the photoluminescence (PL) from the Si nanocrystal assembly and in the excitation of MO from the triplet ground state to singlet excited states. The high efficiency of the energy transfer if favored by a broad energy spectrum of photoexcited excitons, a long triplet exciton lifetime and a highly developed surface area of the nanocrystal assembly. Due to the specifics of the coupled system Si nanocrystal – oxygen molecule all relevant physical parameters describing the photosensitization process are accessible experimentally. This includes the role of resonant and phonon-assisted energy transfer, the dynamics of energy transfer, and its mechanism.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 789 , 2003 , N2.10
Copyright
Copyright © Materials Research Society 2004

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References

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