2008 NSTI Nanotechnology Conference and Trade Show - Nanotech 2008 - 11th Annual

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Clean Technology 2008

Synthesis, Extraction and Surface Modification Of (Zn,Mn)Se Nanocrystals Using Microemulsions As Templates

T. Heckler, Q. Qiu, J. Wang, B. Mei, T.J. Mountziaris
University of Massachusetts, US

Keywords:
quantum dot, microemulsion, zinc selenide, dopant

Abstract:
This research focuses on the novel room temperature synthesis of (Zn,Mn)Se quantum dots that exhibit luminescence peaks at longer wavelengths than the ZnSe bulk emission, due to the Mn ions incorporated in the ZnSe lattice. We employ microemulsion templates formed by self-assembly of a poly-(ethylene-oxide)-poly-(propylene-oxide)-poly (ethylene-oxide) (PEO-PPO-PEO) amphiphilic block copolymer in the presence of a polar and a non-polar solvent. For this work the water / PEO-PPO-PEO / p-xylene system has been used to form microemulsions with water as the dispersed phase and p-xylene as the continuous phase. The precursors for the metals were acetate salts dissolved in water. The formation of the QDs starts with a direct nucleation reaction between the Zn precursor and hydrogen selenide gas that is bubbled through the microemulsion and diffuses to the droplet interface where it undergoes a spontaneous, irreversible reaction with Zn acetate to form ZnSe nuclei. The ions of Mn diffuse into the ZnSe lattice over time and produce doped QDs that exhibit strong luminescence peaks in the orange part of the spectrum. This enables the realization of multi-color QDs based on ZnSe. The (Zn,Mn)Se QDs were then extracted from the microemulsion template and rendered water-dispersible to be used in biological applications.


Nanotech 2008 Conference Program Abstract