Elucidation of Two Giants: Challenges to Thick-Shell Synthesis in CdSe/ZnSe and ZnSe/CdS Core/Shell Quantum Dots

Core/thick-shell giant quantum dots (gQDs) possessing type II electronic structures exhibit suppressed blinking and diminished nonradiative Auger recombination. We investigate CdSe/ZnSe and ZnSe/CdS as potential new gQDs. We show theoretically and experimentally that both can exhibit partial or comp...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2015-03, Vol.137 (11), p.3755-3758
Main Authors: Acharya, Krishna P, Nguyen, Hue M, Paulite, Melissa, Piryatinski, Andrei, Zhang, Jun, Casson, Joanna L, Xu, Hongwu, Htoon, Han, Hollingsworth, Jennifer A
Format: Article
Language:English
Subjects:
Inorganic and Physical Chemistry
Material Science
MATERIALS SCIENCE
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Summary:Core/thick-shell giant quantum dots (gQDs) possessing type II electronic structures exhibit suppressed blinking and diminished nonradiative Auger recombination. We investigate CdSe/ZnSe and ZnSe/CdS as potential new gQDs. We show theoretically and experimentally that both can exhibit partial or complete spatial separation of an excited-state electron–hole pair (i.e., type II behavior). However, we reveal that thick-shell growth is challenged by competing processes: alloying and cation exchange. We demonstrate that these can be largely avoided by choice of shelling conditions (e.g., time, temperature, and QD core identity). The resulting CdSe/ZnSe gQDs exhibit unusual single-QD properties, principally emitting from dim gray states but having high two-exciton (biexciton) emission efficiencies, whereas ZnSe/CdS gQDs show characteristic gQD blinking suppression, though only if shelling is accompanied by partial cation exchange.
ISSN:0002-7863
1520-5126
DOI:10.1021/jacs.5b00313