Synthesis of high-quality core–shell quantum dots of CdSe–CdS by means of gradual heating in liquid paraffin
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Here, we report a novel strategy to prepare fluorescent semiconductor quantum dots (QDs) of core–shell type with CdSe–CdS QDs as a model system. Our synthesis was carried out in liquid paraffin, which is a natural, nontoxic, and cheap solvent. We applied a single injection of precursor for the shell growth at low temperature and gradual heating of the reaction mixture after that. By this manner, the Ostwald ripening of the cores was reduced, homogenous nucleation of the shell material was avoided, and highly monodisperse in size core–shell QDs were prepared. Our synthesis method allows working on open air; it is relatively fast and allows fine control over the shell growth process. It leads to the formation of core–shell CdSe–CdS QDs with fluorescence quantum yield as high as 65%. We described the optical properties of core–shell QDs by the model of attenuated quantum confinement.
KeywordsCdSe CdS CdSe–CdS Core–shell Nanoparticles Nanocrystals Quantum dots Fluorescence Attenuated quantum confinement
The financial support of the Bulgarian Ministry of Education and Science (Project VUH-09/05) is acknowledged. The partial support from the University of Sofia (Project 016/2007 and Project 089/2008) is also acknowledged. G.Y. and C.D. are thankful also to COST Action D43 (grant COST-STSM-D43-02662).
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