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Proceedings Paper

Giant multishell CdSe nanocrystal quantum dots with suppressed blinking: novel fluorescent probes for real-time detection of single-molecule events
Author(s): Jennifer A. Hollingsworth; Javier Vela; Yongfen Chen; Han Htoon; Victor I. Klimov; Amy R. Casson
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Paper Abstract

We reported for the first time that key nanocrystal quantum dot (NQD) optical properties - quantum yield, photobleaching and blinking - can be rendered independent of NQD surface chemistry and environment by growth of a very thick, defect-free inorganic shell (Chen, et al. J. Am. Chem. Soc. 2008). Here, we show the precise shell-thickness dependence of these effects. We demonstrate that 'giant-shell' NQDs can be largely non-blinking for observation times as long as 54 minutes and that on-time fractions are independent of experimental time-resolution from 1-200 ms. These effects are primarily demonstrated on (CdSe)CdS (core)shell NQDs, but we also show that alloyed shells comprising CdxZn1-xS and terminated with a non-cytotoxic ZnS layer exhibit similar properties. The mechanism for suppressed blinking and dramatically enhanced stability is attributed to both effective isolation of the NQD core excitonic wavefunction from the NQD surface, as well as a quasi-Type II electronic structure. The unusual electronic structure provides for effective spatial separation of the electron and hole into the shell and core, respectively, and, thereby, for reduced efficiencies in non-radiative Auger recombination.

Paper Details

Date Published: 3 March 2009
PDF: 7 pages
Proc. SPIE 7189, Colloidal Quantum Dots for Biomedical Applications IV, 718904 (3 March 2009); doi: 10.1117/12.809678
Show Author Affiliations
Jennifer A. Hollingsworth, Los Alamos National Lab. (United States)
Javier Vela, Los Alamos National Lab. (United States)
Yongfen Chen, Los Alamos National Lab. (United States)
Han Htoon, Los Alamos National Lab. (United States)
Victor I. Klimov, Los Alamos National Lab. (United States)
Amy R. Casson, Los Alamos National Lab. (United States)

Published in SPIE Proceedings Vol. 7189:
Colloidal Quantum Dots for Biomedical Applications IV
Marek Osinski; Thomas M. Jovin M.D.; Kenji Yamamoto M.D., Editor(s)

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