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Issue 6, 2012
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Alternating layer addition approach to CdSe/CdS core/shell quantum dots with near-unity quantum yield and high on-time fractions

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Abstract

We report single-particle photoluminescence (PL) intermittency (blinking) with high on-time fractions in colloidal CdSe quantum dots (QD) with conformal CdS shells of 1.4 nm thickness, equivalent to approximately 4 CdS monolayers. All QDs observed displayed on-time fractions >60% with the majority >80%. The high on-time fraction blinking is accompanied by fluorescence quantum yields (QY) close to unity (up to 98% in an absolute QY measurement) when dispersed in organic solvents and a monoexponential ensemble photoluminescence (PL) decay lifetime. The CdS shell is formed in high synthetic yield using a modified selective ion layer adsorption and reaction (SILAR) technique that employs a silylated sulfur precursor. The CdS shell provides sufficient chemical and electronic passivation of the QD excited state to permit water solubilization with greater than 60% QY via ligand exchange with an imidazole-bearing hydrophilic polymer.

Graphical abstract: Alternating layer addition approach to CdSe/CdS core/shell quantum dots with near-unity quantum yield and high on-time fractions

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Publication details

The article was received on 13 Aug 2011, accepted on 16 Mar 2012 and first published on 10 Apr 2012


Article type: Edge Article
DOI: 10.1039/C2SC00561A
Citation: Chem. Sci., 2012,3, 2028-2034
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    Alternating layer addition approach to CdSe/CdS core/shell quantum dots with near-unity quantum yield and high on-time fractions

    A. B. Greytak, P. M. Allen, W. Liu, J. Zhao, E. R. Young, Z. Popović, B. J. Walker, D. G. Nocera and M. G. Bawendi, Chem. Sci., 2012, 3, 2028
    DOI: 10.1039/C2SC00561A

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