Synthesis of Extremely Small CdSe and Bright Blue Luminescent CdSe/ZnS Nanoparticles by a Prefocused Hot-Injection Approach

Although cadmium selenide is a well-explored material in aqueous and hot-injection synthesis of semiconductor quantum dots, only a few syntheses are reported for the preparation of extremely small cadmium selenide nanocrystallites. We present a hot-injection approach based on the enhancement of the nucleation rate to make cadmium selenide quantum dots with a diameter tunable between 1.5 and 2.2 nm. Furthermore, we present a procedure on how to coat these particles with zinc sulfide, leading to highly efficient fluorophors in the blue region of the visible spectrum. The work was performed without the use of highly reactive (pyrophoric) precursors and represents a basic concept for the preparation of small nanoparticles in general.