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J Am Chem Soc. 2011 Jan 12;133(1):24-6. doi: 10.1021/ja108482a. Epub 2010 Dec 13.

Bright and compact alloyed quantum dots with broadly tunable near-infrared absorption and fluorescence spectra through mercury cation exchange.

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Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, 101 Woodruff Circle, Suite 2001, Atlanta, Georgia 30322, USA.


We report a new strategy based on mercury cation exchange in nonpolar solvents to prepare bright and compact alloyed quantum dots (QDs) (Hg(x)Cd(1-x)E, where E = Te, Se, or S) with equalized particle size and broadly tunable absorption and fluorescence emission in the near-infrared. The main rationale is that cubic CdE and HgE have nearly identical lattice constants but very different band gap energies and electron/hole masses. Thus, replacement of Cd(2+) by Hg(2+) in CdTe nanocrystals does not change the particle size, but it greatly alters the band gap energy. After capping with a multilayer shell and solubilization with a multidentate ligand, this class of cation-exchanged QDs are compact (6.5 nm nanocrystal size and 10 nm hydrodynamic diameter) and very bright (60-80% quantum yield), with narrow and symmetric fluorescence spectra tunable across the wavelength range from 700 to 1150 nm.

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