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Compact high-quality CdSe–CdS core–shell nanocrystals with narrow emission linewidths and suppressed blinking


High particle uniformity, high photoluminescence quantum yields, narrow and symmetric emission spectral lineshapes and minimal single-dot emission intermittency (known as blinking) have been recognized as universal requirements for the successful use of colloidal quantum dots in nearly all optical applications. However, synthesizing samples that simultaneously meet all these four criteria has proven challenging. Here, we report the synthesis of such high-quality CdSe–CdS core–shell quantum dots in an optimized process that maintains a slow growth rate of the shell through the use of octanethiol and cadmium oleate as precursors. In contrast with previous observations, single-dot blinking is significantly suppressed with only a relatively thin shell. Furthermore, we demonstrate the elimination of the ensemble luminescence photodarkening that is an intrinsic consequence of quantum dot blinking statistical ageing. Furthermore, the small size and high photoluminescence quantum yields of these novel quantum dots render them superior in vivo imaging agents compared with conventional quantum dots. We anticipate these quantum dots will also result in significant improvement in the performance of quantum dots in other applications such as solid-state lighting and illumination.

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Figure 1: Optical properties of new generation CdSe–CdS core–shell QDs.
Figure 2: Morphology, composition and crystal structure characterization of new generation QDs.
Figure 3: Photoluminescence spectral correlation of single-QDs and ensemble QDs obtained through S-PCFS.
Figure 4: Blinking behaviour of new generation CdSe–CdS core–shell QDs and ensemble photoluminescence stability test.
Figure 5: Water-soluble CdSe–CdS core–shell QDs for in vivo imaging.


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The work received support from the NIH through grants 5-U54-CA119349 (M.G.B.) and 5R01CA126642 (M.G.B., D.F., R.K.J.), the ARO through the Institute for Soldier Nanotechnologies (W911NF-07-D-0004), and the NSF through a Collaborative Research in Chemistry Program (CHE-0714189) (M.G.B.). This work made use of the MRSEC Shared Experimental Facilities at MIT, supported by the National Science Foundation under award number DMR-08-19762 and the MIT DCIF NMR spectrometer funded through National Science Foundation Grants CHE-9808061 and DBI-9729592.

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O.C. and M.G.B. conceived and designed the project. O.C. performed the bulk of the experimental work with help from J.Z., V.P.C., J.C., C.W., D.K.H., H.W. and H-S.H. The data was analysed by O.C., J.Z., V.P.C., J.C., C.W. and M.G.B. All authors discussed the results and took part in producing the manuscript.

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Correspondence to Moungi G. Bawendi.

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The authors declare no competing financial interests.

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Chen, O., Zhao, J., Chauhan, V. et al. Compact high-quality CdSe–CdS core–shell nanocrystals with narrow emission linewidths and suppressed blinking. Nature Mater 12, 445–451 (2013).

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