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Stability and Fluorescence Quantum Yield of CdSe–ZnS Quantum Dots—Influence of the Thickness of the ZnS Shell
Author(s) -
Grabolle Markus,
Ziegler Jan,
Merkulov Alexei,
Nann Thomas,
ReschGenger Ute
Publication year - 2008
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1430.021
Subject(s) - quantum yield , quantum dot , fluorescence , thiophenol , shell (structure) , yield (engineering) , chemistry , materials science , photochemistry , nanotechnology , optoelectronics , optics , physics , composite material , organic chemistry
We investigated the correlation between the thickness of the ZnS shell of CdSe–ZnS quantum dots (QDs), the stability of the particles, and the fluorescence quantum yield. As a measure for stability, a new shell quality test was developed. This test is based on the reaction of the QDs with photochemically formed thiophenol radicals and communicates an imperfect ZnS shell by a rapid and complete loss of fluorescence. The quantum yield increases from less than 5% for unshelled CdSe up to 50%, with an increase in ZnS shell thickness up to 0.6–0.8 nm. At the same time, the particles become significantly more stable, as revealed by the shell test.