Synthesis of ZnSe quantum dots and ZnSe-ZnS core/shell nanostructures

Colloidal ZnSe nanocrystals were synthesized in hot mixtures of long-chain alkylamines, fatty acids, and alkylphosphines. It was possible to tune the size of nanocrystals by varying the reaction time. Transmission electron microscope images showed the presence of spherical ZnSe nanocrystals and X-ray diffraction pattern of ZnSe nanocrystals showed the existence of both the crystalline phase, namely, wurtzite and zinc blencle. The ZnSe nanocrystals were then passivated with higher band gap ZnS; this lead to a 2.6-fold enhancement in the integrated photoluminescence intensity of ZnSe nanocrystals. We also synthesized the reverse type core/shell ZnS/ZnSe nanocrystals. These exhibited a significant red shift in the absorption edge after coating with a thin ZnSe shell.