Comprehensive Route to the Formation of Alloy Interface
in Core/Shell Colloidal Quantum Dots
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Abstract
The electronic properties of colloidal
quantum dots (CQDs) have
shown intriguing potential in recent years for implementation in various
optoelectronic applications. However, their chemical and photochemical
stabilities, mainly derived from surface properties, have remained
a major concern. This paper reports a new strategic route for the
synthesis of surface-treated CQDs, the CdSe/CdS core/shell heterostructures,
based on low-temperature coating of a shell constituent, followed
by a programmed annealing process. A comprehensive follow-up of the
stability and the optical properties through the various synthesis
stages is reported, suggesting that the low-temperature coating is
responsible for the formation of a sharp interface between the core
and the shell, whereas a postcoating annealing process leads to the
generation of a thin alloy interfacial layer. At the end of the process,
the CdSe/CdS CQDs show a significant improvement of the photoluminescence
quantum yield, as well as an exceptional photostability. Consequently,
the work reported here provides a convenient generic route to the
formation of core/shell CQDs to be employed as a procedure for achieving
various other heterostructures