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Non-blinking semiconductor nanocrystals

A Retraction to this article was published on 28 October 2015


The photoluminescence from a variety of individual molecules1 and nanometre-sized crystallites2 is defined by large intensity fluctuations, known as ‘blinking’, whereby their photoluminescence turns ‘on’ and ‘off’ intermittently, even under continuous photoexcitation2. For semiconductor nanocrystals, it was originally proposed3 that these ‘off’ periods corresponded to a nanocrystal with an extra charge. A charged nanocrystal could have its photoluminescence temporarily quenched owing to the high efficiency of non-radiative (for example, Auger) recombination processes between the extra charge and a subsequently excited electron–hole pair; photoluminescence would resume only after the nanocrystal becomes neutralized again. Despite over a decade of research, completely non-blinking nanocrystals4,5 have not been synthesized and an understanding of the blinking phenomenon6 remains elusive. Here we report ternary core/shell CdZnSe/ZnSe semiconductor nanocrystals that individually exhibit continuous, non-blinking photoluminescence. Unexpectedly, these nanocrystals strongly photoluminesce despite being charged, as indicated by a multi-peaked photoluminescence spectral shape and short lifetime. To model the unusual photoluminescence properties of the CdZnSe/ZnSe nanocrystals, we softened the abrupt confinement potential of a typical core/shell nanocrystal, suggesting that the structure is a radially graded alloy of CdZnSe into ZnSe. As photoluminescence blinking severely limits the usefulness of nanocrystals in applications requiring a continuous output of single photons, these non-blinking nanocrystals may enable substantial advances in fields ranging from single-molecule biological labelling7 to low-threshold lasers8.

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Figure 1: Non-radiative Auger-like recombination and potential energy functions of nanocrystals.
Figure 2: Single-nanocrystal images and photoluminescence intensity time traces.
Figure 3: Anti-bunching measurements.
Figure 4: Single-nanocrystal photoluminescence spectra and the shake-up process.

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We acknowledge financial support by the DOE (DE-FC26-06NT42864), NSF (CHE 0616378, CHE 0619418, EEC-0117770, DMR-9632275), NYSTAR, University of Rochester Center for Electronic Imaging Systems, the Cornell Center for Nanoscale Systems, the Office of Naval Research and the Alexander von Humboldt Foundation (A.L.E.).

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Correspondence to Keith Kahen, Alexander L. Efros or Todd D. Krauss.

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This file contains Supplementary Methods, Supplementary Data, Supplementary Figures S-1 - S-4 with Legends, Supplementary Table S-I-S-II and Supplementary References. (PDF 1179 kb)

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Wang, X., Ren, X., Kahen, K. et al. Non-blinking semiconductor nanocrystals. Nature 459, 686–689 (2009).

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