Environment-Induced Structure Change of As-Prepared Aqueous CdTe Nanocrystals

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• 作者：Hao Zhang ; Dayang Wang ; J&uuml ; rgen Hartmann ; Helmuth Mö ; hwald
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：July 12, 2007
• 年：2007
• 卷：111
• 期：27
• 页码：9678 - 9683
• 全文大小：464K
• 年卷期：v.111,no.27(July 12, 2007)
• ISSN：1932-7455

文摘

In the present work, we explored the structure evolution of preformed aqueous quantum dots (QDs) of metallicchalcogenides upon variation of the QD concentration, the incubation temperature, and the stabilizing ligands.The variation of the surrounding media was found to efficiently facilitate diffusion of the monomers from thesmaller QDs to the larger ones in the preformed QD ensembles, thus leading to size increase and even shapeelongation in the presence of ligands with molecular structures like thioglycolic acid (TGA). A detectableshift of both absorption and luminescence bands of the QDs was observed accordingly. This environment-sensitive monomer dissolution can be reasonably explained by the Gibbs-Thomson equation. Due to thissensitivity, the structure variation was visible by mixing suspensions of two different preformed QDs ofmetallic chalcogenides. As compared with the chemistry sensitivity of preformed aqueous QDs of metallicchalcogenides to the surrounding variation, this newly found structure sensitivity should pave an alternativebut complementary way to account for the strong luminescence dependence of the preformed QDs on theparticle size, the particle concentration, the ligand nature, and the storage period. On the other hand,transformation of preformed spherical QDs to elongated ones, using TGA-like ligands or their capped QDs,provides new pathways to form aqueous nanorods or nanowires, especially composite ones.