Synthesis of Colloidal ZnSe Nanospheres by Ultrasonic-Assisted Aerosol Spray Pyrolysis

Colloidal monodisperse ZnSe nanospheres consisting of primary nanocrystals were prepared by aerosol spray pyrolysis with ultrasonic nebulization. The formation mechanism of nanospheres seems to be generation of primary ZnSe nanocrystals and subsequent aggregation of primary nanocrystals in a tube reactor. Monodispersed ZnSe nanospheres were found to be synthesized only from a specific mixture of precursors at a reaction temperature of 525 degrees C. Typical ratios were ZnO (5 mmol)/OA (10 mL)/TOPO (2 g)/ODE (10 mL) as a Zn precursor and Se (10 mmol)TOP (5 mL)/ODE (5 mL as a Se precursor. Those ZnSe nanoparticles were characterized by TEM, EDX, FT-IR, UV-vis, and PL techniques. The TEM image shows that the average diameter of ZnSe nanospheres is 41 nm, and primary ZnSe nanocrystals have a size of 2-3 nm. The XRD pattern of ZnSe nanoparticles shows that the crystal structure is zinc blende. The ZnSe nanospheres were confirmed to have a quantum size effect in their optical spectra and exhibit near band-edge luminescence.