Effect of Small Molecule Additives in the Prenucleation Stage of Semiconductor CdSe Quantum Dots.

For the addition of small molecules in the prenucleation stage of colloidal CdSe conventional quantum dots (QDs), there is insufficient knowledge regarding what are advantageous circumstances. Here, we present a study about such addition. When CH3COOH or Zn(OOCCH3)2 is added in the prenucleation stage (at 120 °C) of a reaction consisting of cadmium myristate (Cd(OOC(CH2)12CH3)2, Cd(MA)2 made from CdO) and Se powder in 1-octadecene (ODE), CdSe magic-size clusters (MSCs) exhibiting a single sharp absorption doublet at 433/460 nm are synthesized in a single-ensemble form (around 220 °C). We demonstrate that such small molecule addition suppresses the nucleation and growth of QDs and thus directs a competitive process to the formation of MSCs. The present study provides insight into the individual but linked pathways to forming CdSe QDs and MSCs and introduces new avenues to improve the production of MSCs through the addition of small molecules in the prenucleation stage.