title: Bright and compact alloyed quantum dots with broadly tunable near-infrared absorption and fluorescence spectra through mercury cation exchange.
abstract: 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.
authors.affiliation: Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, 101 Woodruff Circle, Suite 2001, Atlanta, Georgia 30322, USA.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Smith
authors.forename: Shuming
authors.initials: S
authors.lastname: Nie
mesh_terms: D000042:Absorption; D000497:Alloys / Q000737:chemistry*; D007474:Ion Exchange; D008628:Mercury / Q000737:chemistry*; D010316:Particle Size; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence; D013055:Spectrophotometry, Infrared
chemical_list: D000497:Alloys; D008628:Mercury