Issue 6, 2012

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

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

Supplementary files

Article information

Article type
Edge Article
Submitted
13 Aga 2011
Accepted
16 Mas 2012
First published
10 Eph 2012

Chem. Sci., 2012,3, 2028-2034

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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