Issue 3, 2009

Formation of two types of highly luminescent SiO2 beads impregnated with multiple CdTe QDs

Abstract

Highly luminescent SiO2 beads with concentrated CdTe quantum-dots (QDs) stabilized by thioglycolic acid (TGA) have been prepared by using a two-step synthesis including coating the surface of the QDs with SiO2 and subjecting them to a subsequent inverse micelle process. Two types of bead structures were formed together with a solid structure, depending on the preparation procedures and conditions. The first contains a composite consisting of Cd2+, TGA, SiO2, and QDs (with egg-yolk structure). This composite was created when highly alkaline water (pH ≥10) was added to the solution of surface-coated QDs before a sol–gel reaction occurred in the water droplets though the migration of the content inside the droplets before they solidified. The second contains a void inside of them (hollow structure). This void was formed when highly alkaline water was added after the water droplets had formed. The beads thus prepared demonstrated high photoluminescence efficiency (70%, almost same as the initial colloidal solution) that was maintained for more than a week in water. The lifetime measurement indicates the reduction of non-radiative rate and increment of radiation lifetime of QDs by the SiO2 coating. The mean concentration of QDs in typical beads was about 0.002 M, where ca. 140 QDs were dispersed in all SiO2 beads 60 nm in diameter.

Graphical abstract: Formation of two types of highly luminescent SiO2 beads impregnated with multiple CdTe QDs

Article information

Article type
Paper
Submitted
04 Jun 2008
Accepted
27 Oct 2008
First published
01 Dec 2008

New J. Chem., 2009,33, 561-567

Formation of two types of highly luminescent SiO2 beads impregnated with multiple CdTe QDs

P. Yang, M. Ando and N. Murase, New J. Chem., 2009, 33, 561 DOI: 10.1039/B809478K

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