Synthesis of Monodisperse CdSe Nanocrystals: Nucleation and Growth

With trioctylphosphine and oleic acid as the ligands of Se and Cd, high-quality CdSe nanocrystals with controlled particle size were synthesized in a 260～300 ℃ noncoordinating solvent octadecene under argon flow. The as-synthesized nanocrystals are monodisperse without any size-selective treatment, and exhibit the clear quantum confinement effect, which makes the first excitonic absorption peak shift to red with increasing particle size. The shape of the emission peak and the reasonable Stokes shift (13 nm) indicate that these nanocrystals have intense band-gap emission, devoid of significant trap-state emission. In addition, experimental results show that the rate of nucleation and subsequent growth can be easily tuned by altering the concentration of trioctylphosphine, by which monodisperse CdSe nanocrystals can be also obtained.