ZnSe quantum dots within CdS nanorods: A seeded-growth type-II system

ZnSe seeded CdS nanorods with high optical quality was grown, demonstrating the extension of the powerful seeded-rod-growth approach to a system with a seed like cubic structure. These seeds were mixed with the sulfur precursor and rapidly injected into a hot solution of the cadmium precursor and two phosphonic acids in tri-n-octylphosphine oxide (TOPO). The powder X-ray diffraction (XRD) patterns of the ZnSe nanocrystals correspond to a face-centered cubic (fcc) crystal structure. High-resolution (HR)TEM analysis was performed on several rods. The charge-carrier separation in the excited state should cause a longer emission lifetime compared to a type-I transition, which can actually be observed very clearly. Both structural and optical characterizations clearly prove the successful formation of CdS nanorods with ZnSe seeds, through the seeded-growth approach.