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Noninjection, one-pot synthesis of Cu-deficient CuInS₂/ZnS core/shell quantum dots and their fluorescent properties

Nam, Da-Eun, Song, Woo-Seuk, Yang, Heesun
Journal of colloid and interface science 2011 v.361 no.2 pp. 491-496
coatings, copper, fluorescence, quantum dots, stoichiometry, wavelengths
Non-toxic, environment-benign colloidal CuInS₂ (CIS) quantum dots (QDs) were synthesized through a facile noninjection, one-pot approach by reacting Cu and In precursors with dodecanethiol dissolved in 1-octadecence at 220°C. The Cu:In precursor molar ratio was varied from 1:1 to 1:4 to intentionally generate Cu-deficient CIS QDs. Depending on the stoichiometry of the QDs, their emission peak wavelengths were tuned in red–deep red region. More Cu-deficient CIS QDs (Cu:In=1:4) were found to be more efficient than ones with Cu:In=1:1. After successive ZnS shell was overgrown on the surface of core QDs with Cu:In=1:4, the resulting core/shell QDs exhibited a highly efficient yellow emission with a quantum yield of ∼50%. A substantially blue-shifted emission from the core/shell QDs versus core ones was described by suggesting an alternative recombination pathway that may be induced by the ZnS shell coating.