Colloidal CdSe nanocrystals from tri-n-octylphosphine with various Cd sources: Control of a slow growth for high-quality and large-scale production

A slow growth in size at the early stages of reaction, together with a period of zero growth in size and size distribution is observed via monitoring the temporal evolution of the optical properties of the growing CdSe nanocrystals from reaction media consisting of tri-n-octylphosphine (TOP). The synthetic approach is as simple as a swift injection of a TOPSe/TOP solution into a Cd-source/TOP solution at 300 °C with subsequent growth at 250 °C. The various Cd sources investigated are cadmium acetate (Cd(Ac)2), cadmium oxide (CdO)/tetradecylphosphonic acid (TDPA), CdO, and CdO/oleylamine (OLA). With these various Cd sources studied, CdO with a 4Cd-to-1Se stoichiometry demonstrates its suitability for high-quality and large-scale production, due to a slow growth in size (less than 17 nm redshift of bandgap absorption and emission) and size distribution, as well as fairly constant photoluminescent properties of the growing nanocrystals during the 0.5-60 min growth time.