Highly luminescent blue emitting CdS/ZnS core/shell quantum dots via a single-molecular precursor for shell growth

Highly luminescent blue-emitting CdS/ZnS core/shell quantum dots (QDs) were synthesized in N-oleoylmorpholine by two facile steps: first, the CdS core QDs were prepared via a simple one-pot method involving a direct reaction of Cd precursor cadmium stearate and S precursor S powder in solvent N-oleoylmorpholine; second, ZnS shells were successively overcoated on CdS core through the decomposition of single molecular precursor zinc diethyldithiocarbamate. The thickness of shell was precisely tuned by controlling drip feed speed and amount of shell precursor. The obtained CdS/ZnS core/shell QDs showed the maximum photoluminescent quantum yield of 54.8% and narrow spectra bandwidth, exhibiting high monodispersity, good color purity and long fluorescent lifetimes. The CdS/ZnS core/shell QDs with tunable emission wavelength of 424–470 nm were obtained by controlling the thickness of ZnS shell overgrown on different-sized CdS QDs, which are promising materials for blue light-emitting devices.

► A one-pot approach was used for the synthesis of high-quality CdS core quantum dots at the absence of any nucleation initiators. ► The thickness of ZnS shell on CdS core could be precisely tuned by controlling drip feed speed and amount of the shell precursor solution. ► A new, air-stable, and low-cost benign reagent N-oleoylmorpholine was used as solvent. ► The single-source molecular precursor used provides the mild, safe, and simplified fabrication procedure. ► The CdS/ZnS core/shell QDs exhibit high monodispersity, good color purity and long fluorescent lifetimes.