Biomedical Engineering Reference
In-Depth Information
Chapter 4
Formation Principles and Exciton Relaxation
in Semiconductor Quantum Dot-Dye
Nanoassemblies
Christian von Borczyskowski and Eduard Zenkevich
Abstract
In this chapter we discuss “bottom-up” non-covalent self-assembly
principles which define a strategy for the formation of organic-inorganic
nanoassemblies containing colloidal semiconductor quantum dots (QD) of different
types (based on a CdSe core) and various heterocyclic molecules (dyes) with
functionalized anchoring side substituents (
meso
-pyridyl substituted porphyrins
and perylene diimides). Using a combination of ensemble and single molecule
spectroscopy of “QD-Dye” nanoassemblies, we show that single functionalized
molecules can be considered as extremely sensitive probes for studying the
complex interface physics and chemistry (influence of the embedding environment
and temperature) and related exciton relaxation processes in QDs. It will be
quantitatively laid out that the major part of the observed QD photoluminescence
(PL) quenching in nanoassemblies can be understood, on the one hand, in terms
of exciton wave function tunneling under the condition of quantum confinement
and, on the other hand, by the influence of ligand dynamics. In nanoassemblies,
photoinduced Foerster-type energy transfer (FRET) QD
Dye is often only a small
contribution to the PL quenching and is effectively suppressed already in slightly
polar solvents which is often overlooked in literature. Finally we would like to
point out that properties of “QD-Dye” nanoassemblies are not only interesting in
themselves but also provide a valuable tool to study surface-related phenomena in
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C. von Borczyskowski (
)
Institute of Physics and Centre for Nanostructured Materials and Analytics (nanoMA), Chemnitz
University of Technology, Reichenhainerstr. 70, Chemnitz, 09107 Germany
E. Zenkevich
Department of Information Technologies and Robotics, National Technical University of Belarus,
Prospect Nezavisimosti 65, Minsk, 220013 Belarus
e-mail:
zenkev@tut.by
