Synthesis of highly luminescent Mn:ZnSe/ZnS nanocrystals in aqueous media

Abstract

High-quality water-dispersible Mn(2+)-doped ZnSe core/ZnS shell (Mn:ZnSe/ZnS) nanocrystals have been synthesized directly in aqueous media. Overcoating a high bandgap ZnS shell around the Mn:ZnSe cores can bring forward an efficient energy transfer from the ZnSe host nanocrystals to the dopant Mn. The quantum yields of the dopant Mn photoluminescence in the as-prepared water-soluble Mn:ZnSe/ZnS core/shell nanocrystals can be up to 35 +/- 5%. The optical features and structure of the obtained Mn:ZnSe/ZnS core/shell nanocrystals have been characterized by UV-vis, PL spectroscopy, TEM, XRD and ICP elementary analysis. The influences of various experimental variables, including the Mn concentration, the Se/Zn molar ratio as well as the kind and amount of capping ligand used in the core production and shell deposition process, on the luminescent properties of the obtained Mn:ZnSe/ZnS nanocrystals have been systematically investigated.

Quantum dot-based “turn-on” fluorescent probe for detection of zinc and cadmium ions in aqueous media

“…In the control experiment, only Zn 2+ was added to the plain CdTe QDs solution. The samples before ICP-AES test were washed thoroughly with acetone followed by ethanol to rinse away any metal ions adsorbed at the surface of the nanoparticles as reported in the literature [57]. The amounts of Zn and Cd in the so-called CdTe/ZnS sample and in the control experiment were determined by ICP-AES technique after a standard HCl/HNO 3 digestion.…”

Mn-Doped ZnSe Quantum Dots as Fluorimetric Mercury Sensor

“…Cubic structures are often obtained in the low-temperature aqueous synthesis of ZnSe QDs. This indicates that the incorporation of Mn 2+ into the host ZnSe does not bring any obvious change in the crystal lattice and the structure [37,54]. TEM image of the 3% Mn:ZnSe QDs (Figure 5a) shows that QDs are spherical in nature with the average diameter of ~4 nm.…”

“…-doped ZnSe core/ZnS shell (Mn:ZnSe/ZnS) nanocrystals directly in aqueous media with MPA as the capping ligand [54]. They observed that there was almost no dopant Mn emission in the Mn:ZnSe d-dots and bright Mn luminescence was observed after overcoating the ZnS shell around the Mn:ZnSe dots.…”

“…This transition is spin-forbidden but is allowed because of crystal field effects [55]. Fang et al [54] notified that if the dopant ions are adsorbed on the surface of the host nanocrystal instead of being incorporated into its lattice, no dopant emission is observed and further the host emission is drastically quenched because a loosely adsorbed dopant ion can easily act as a surface trap that quenches the host PL [57]. However, in the present system, after doping with 3% Mn, the luminescence of host emission is enhanced by 7.7 times along with the appearance of Mn emission.…”

Au:CdHgTe quantum dots for in vivo tumor-targeted multispectral fluorescence imaging

“…The Au:CdHgTe QDs were synthesized by an aqueous solution route [5,6,36,[41][42][43][44][45][46][47][48][49][50][51][52][53][54] with L-glutathione and Lcysteine as stabilizers [37]. In a typical experiment, the procedures were as follows: (1) 0.20 mmol CdCl 2 ·2.5H 2 O, 0.06 mmol L-glutathione, 0.24 mmol L-cysteine, 60 μmol HgCl 2 , and 15 μmol AuCl 3 ·HCl·4H 2 O were dissolved in 200 mL water.…”