Nanotech 2010

Microwave-assisted synthesis of water soluble ZnSe@ZnS quantum dots

S.J. Bailon-Ruiz, O. Perales-Perez, S.P. Singh
University of Puerto Rico at Mayaguez, PR

Keywords: quantum dots, nanocrystals, semiconductors, microwave-assisted


Semiconductors nanocrystals known as quantum dots (QD’s) have attracted much attention because of their optical properties can be tuned just by controlling their crystal-size, composition and shape at the nanoscale. Compared to organic dyes, quantum dots are characterized by their narrow emission spectra, high quantum yield, high chemical stability, photobleaching stability and surface functionality. These mentioned properties justify the use of quantum dots as promising candidates for photodynamic therapy (PDT) applications, biomarkers and also optoelectronics applications. Under these premises, the main focus on this study is on the synthesis of water soluble ZnSe@ZnS quantum dots in one step. Regarding the type of candidate materials novel Zn-based QD’s are becoming potential replacements of Cd-based chalcogenides, which are expected to exhibit toxic effects in envisioned biomedical applications. Microwave-assisted synthesis is an attractive method to produce QD’s because of its high heating rate, more-environmental friendly and homogeneous heating capability which promotes the QD’s crystallinity and optical properties. Zinc chloride and selenium solutions were mixed in a microwave digestion vessel in presence of a thiol (thioglycolic acid or TGA) at pH 7.0. The formation of the ZnSe@ZnS quantum dots was confirmed by X-ray diffraction, transmission-electron microscopy, ICP-MS analysis and optical characterization techniques.
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