CdSe, a II–VI type semiconductor, is a widely st

CdSe, a II–VI type semiconductor, is a widely studied nanocrystal (NC) in colloidal science as its emission can cover the whole visible spectrum via size tuning,1,2 making CdSe NCs important for several applications such as biolabeling and LEDs.3,4 Despite having interesting functional properties, NCs in general suffer from instability, in particular surface oxidation,5,6 due to the high surface to volume ratio. In order to increase the stability of CdSe QDs, a wide-band gap II–VI semiconductor such as ZnS can be successfully grown onto a CdSe core. The advantage of a wide-band gap ZnS shell is that both electrons and holes are kept confined in the core with increased stability as well as decreased toxicity.7–10 However, the lattice mismatch in the CdSe–ZnS core–shell system is about 12%, leading to interfacial strain, thus resulting in the formation of trap sites for charge carriers and increased blinking.1,8,11–13 In order to overcome this problem, an intermediate layer of CdS with a lattice constant between CdSe and ZnS can be incorporated into the structure.7,14–16 With this CdS intermediate layer, the interfacial strain is reduced and the optical properties are enhanced.7,14–16 We thus speak of CdSe–CdS–ZnS core–multishell QDs.

http://pubs.rsc.org/en/content/articlehtml/20...c4cc08647c

...this was published in Nov 2014. We now have cfqd QDX tm: I can only imagine ....


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