High fluorescence quantum efficiency of CdSe/ZnS quantum dots embedded in GPTS/TEOS-derived organic/silica hybrid colloids

Rod-like particles growing in sol–gel processing of 1:1 molar mixtures of 3-glycidoxypropyltrimethoxysilane and tetraethoxysilane

The growth kinetics and the structure of organic/silica hybrids prepared from acid hydrolysis of 1:1 molar mixtures of 3-glycidoxypropyltrimethoxysilane and tetraethoxysilane were studied by small-angle X-ray scattering (SAXS) at 315, 325 and 335 K. The evolution of the SAXS intensity is compatible with the growth of silica-rich domains by aggregation from a fixed number of primary particles. Two distinct growth regimes could be identified by analyzing the relation I(0) ∝ R g D between the intensity extrapolated to zero I(0), the radius of gyration R g of the aggregates and the exponent D, which gives information on the geometry and the mechanism of growth of the aggregates. An initial period was attributed to the growth of rod-like particles with approximately the same radius and variable length. At more advanced degrees of aggregation the process was controlled by the growth of larger aggregates with higher-order dimensionality. A narrow distribution of cylinder lengths given by the Schulz function fitted the experimental SAXS data well during the most part of the initial regime of cylindrical particle growth. These particles were later found as rod-like subunits of the larger aggregates grown at more advanced degrees of aggregation. Some condensation possibilities yielding the formation of structures compatible with those inferred from the present study are discussed.

Facile surface engineering of CuInS2/ZnS quantum dots for LED down-converters

Surface engineered CuInS₂ quantum dots with extraodrinary properties in polymer nanocomposites and high stability in sol–gel silica are presented herein.