One-pot synthesis of homogeneous CdSexS1-x alloyed quantum dots with tunable composition in a green N-oleoylmorpholine solvent

Composition-tunable ternary CdSexS1-x quantum dots (shortened form, CdSeS QDs) with different emission colors were prepared via a non-injection, one-pot approach in a green N-oleoylmorpholine solvent for the first time, with air-stable compounds cadmium oxide (CdO), selenium (Se) powder, and sulfur (S) powder as Cd, Se, and S sources, respectively. The synthesis of ternary alloyed CdSeS QDs with homogeneous composition were performed by mixing cadmium oleate solution obtained from the reaction between CdO and oleic acid, and the premixed solution containing Se and S in N-oleoylmorpholine solvent. The resulting CdSexS1-x QDs were characterized through UV-visible absorption spectrophotometer and fluorescence spectrophotometer, and they exhibited well-resolved absorption feature and dominant band-edge emission with a moderate size distribution (the full width at half maximum (FWHM) was 30-50 nm). The maximum photoluminescent (PL) quantum yield (QY) was as high as 60%. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) patterns suggested that the as-prepared ternary QDs possessed high crystalline and a cubic zinc-blende structure. In addition, the results indicated that the similar reactivity between S/N-oleoylmorpholine and Se/N-oleoylmorpholine is responsible for the homogeneous structure of the as-obtained CdSeS alloyed QDs. The as-prepared CdSexS1-x QDs exhibit sharp emission features and various colors. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)