Enhancing the photoluminescence of polymer-stabilized CdSe/CdS/ZnS core/shell/shell and CdSe/ZnS core/shell quantum dots in water through a chemical-activation approach.
We report a method for preparing highly photoluminescent, water-soluble CdSe/CdS/ZnS core/shell/shell and CdSe/ZnS core/shell quantum dots (QDs) colloidally stabilized by double hydrophilic copolymers. The polymers, either a diblock copolymer poly(ethylene glycol-b-2-N,N-dimethylaminoethyl methacrylate) (PEG-b-PDMA) or a statistical copolymer poly(oligoethylene glycol methacrylate-co-2-N,N-dimethylaminoethyl methacrylate) (POEG-co-PDMA), were able to replace the hexadecylamine (HDA) or trioctylphosphine oxide (TOPO) ligands on the surface of the as-synthesized QDs and impart water-solubility and colloidal stability to the QD nanocrystals. In water, the [CdSe/ZnS]/POEG-co-PDMA colloids were present in the form of aggregates with a mean apparent hydrodynamic radius Rh of 54 nm and a narrow size distribution. Although the photoluminescence (PL) quantum yield (QY) of the polymer-treated QDs decreased upon transfer from an organic medium to water, much of this loss in brightness could be restored by the addition to the solution of an excess of a water-soluble primary amine such as 3-amino-propanol (APP). This chemical-activation strategy of adding primary amines as PL activators to polymer-stabilized QDs did not lead to a spectral shift of either the absorption or emission of the QDs in water.
Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, M5S 3H6 Ontario, Canada.
Mingfeng
M
Wang
Meng
M
Zhang
Jieshu
J
Qian
Fei
F
Zhao
Lei
L
Shen
Gregory D
GD
Scholes
Mitchell A
MA
Winnik
D000588:Amines / Q000737:chemistry; D019187:Cadmium Compounds / Q000737:chemistry*; D006838:Hydrocarbons; D008024:Ligands; D008163:Luminescent Measurements; D011108:Polymers / Q000737:chemistry*; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
D000588:Amines; D019187:Cadmium Compounds; D006838:Hydrocarbons; D008024:Ligands; D011108:Polymers; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; C034939:cadmium sulfide; D014867:Water; C058667:cadmium selenide; C031238:zinc sulfide; C013553:hexadecylamine