title: Large scale synthesis of stable tricolor Zn(1-x)Cd(x)Se core/multishell nanocrystals via a facile phosphine-free colloidal method.
abstract: Here we report a new "green" method to synthesize Zn(1-x)Cd(x)Se (x = 0-1) and stable red-green-blue tricolor Zn(1-x)Cd(x)Se core/shell nanocrystals using only low cost, phosphine-free and environmentally friendly reagents. The first excitonic absorption peak and photoluminescence (PL) position of the Zn(1-x)Cd(x)Se nanocrystals (the value of x is in the range 0.005-0.2) can be fixed to any position in the range 456-540 nm. There is no red or blue shift in the entire reaction process. Three similar sizes of alloyed Zn(1-x)Cd(x)Se nanocrystals with blue, green, and yellow emissions were successfully selected as cores to synthesize high quality blue, green, and red core/shell nanocrystal emitters. For the synthesis of core/shell nanocrystals with a high quantum yield (QY) and stability, the selection of shell materials has been proven to be very important. Therefore, alternative protocols have been used to optimize thick shell growth. ZnSe/ZnSe(x)S(1-x) and CdS/Zn(1-x)Cd(x)S have been found as an excellent middle multishell to overcoat between the alloyed Zn(1-x)Cd(x)Se core and ZnS outshell. The QYs of the as-synthesized core/shell alloyed Zn(1-x)Cd(x)Se nanocrystals can reach 40-75%. The Cd content is reduced to less than 0.1% for Zn(1 -x)Cd(x)Se core/shell nanocrystals with emissions in the range 456-540 nm. More than 15 g of high quality Zn(1-x)Cd(x)Se core/shell nanocrystals were prepared successfully in a large scale, one-pot reaction. Importantly, the emissions of such thick multishell nanocrystals are not susceptible to ligand loss and stability in various physiological conditions.
authors.affiliation: Key Laboratory for Special Functional Materials, Henan University, Kaifeng, 475004, PR China.
authors.forename: Huaibin
authors.initials: H
authors.lastname: Shen
authors.forename: Hongzhe
authors.initials: H
authors.lastname: Wang
authors.forename: Changhua
authors.initials: C
authors.lastname: Zhou
authors.forename: Jin Zhong
authors.initials: JZ
authors.lastname: Niu
authors.forename: Hang
authors.initials: H
authors.lastname: Yuan
authors.forename: Lan
authors.initials: L
authors.lastname: Ma
authors.forename: Lin Song
authors.initials: LS
authors.lastname: Li
mesh_terms: D000497:Alloys / Q000138:chemical synthesis*; D002104:Cadmium / Q000737:chemistry*; D055772:Green Chemistry Technology / Q000191:economics / Q000379:methods*; D049449:Luminescence; D053758:Nanoparticles / Q000737:chemistry*; D010720:Phosphines; D012643:Selenium / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D000497:Alloys; D010720:Phosphines; D002104:Cadmium; C044646:phosphine; D012643:Selenium; D015032:Zinc