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Influence of the Inner-Shell Architecture on Quantum Yield and Blinking Dynamics
in Core/Multishell Quantum Dots
#MMPMID26693950
Bajwa P
; Gao F
; Nguyen A
; Omogo B
; Heyes CD
Chemphyschem
2016[Mar]; 17
(5
): 731-40
PMID26693950
show ga
Choosing the composition of a shell for QDs is not trivial, as both the band-edge
energy offset and interfacial lattice mismatch influence the final optical
properties. One way to balance these competing effects is by forming multishells
and/or gradient-alloy shells. However, this introduces multiple interfaces, and
their relative effects on quantum yield and blinking are not yet fully
understood. Here, we undertake a systematic, comparative study of the addition of
inner shells of a single component versus gradient-alloy shells of cadmium/zinc
chalogenides onto CdSe cores, and then capping with a thin ZnS outer shell to
form various core/multishell configurations. We show that architecture of the
inner shell between the CdSe core and the outer ZnS shell significantly
influences both the quantum yield and blinking dynamics, but that these effects
are not correlated-a high ensemble quantum yield doesn't necessarily equate to
reduced blinking. Two mathematical models have been proposed to describe the
blinking dynamics-the more common power-law model and a more recent
multiexponential model. By binning the same data with 1 and 20?ms resolution, we
show that the on times can be better described by the multiexponential model,
whereas the off times can be better described by the power-law model. We discuss
physical mechanisms that might explain this behavior and how it can be affected
by the inner-shell architecture.
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