Effects of Core Size and
Shell Thickness on Luminescence
Dynamics of Wurtzite CdSe/CdS Core/Shell Nanocrystals
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Abstract
Colloidal CdSe nanocrystals (NCs), whose size is 2.8,
3.8, and 4.9 nm, respectively, were successively overcoated with CdS
monolayers (MLs).
The X-ray diffraction patterns indicated that the stress in the wurtzite
CdSe core was increased with the epitaxial growth of CdS shell, and
the CdSe lattice contraction, which was sensitive to core size, did
not release with the CdS shell toward 5 MLs. The effects of the CdSe
core size and the CdS shell thickness on the temperature-dependent
photoluminescence (PL) lifetime were investigated. The PL lifetime
undulation with temperature is indicative of the spatial distribution
of trap states, and the strong interplay between intrinsic excitons
and surface traps can be activated even in the case of the NCs with
5 ML CdS shell