Evolution of CdTe Magic-Size Clusters with Single Absorption Doublet Assisted by Adding Small Molecules during Prenucleation.

An approach is reported for the exclusive production of CdTe magic-size clusters (MSCs) that exhibit an optical absorption doublet peaking at 385/427 nm, with an explanation of the synthesis procedure. The MSCs, defined as dMSC-427, were produced from the reaction of cadmium oleate (Cd(OA)) and tri--octylphosphine telluride in octadecene at 100 °C, with the addition of acetic acid (HOAc) or acetate (M(OAc)) during the prenucleation stage (40 °C). Without such an addition or when it was performed in the postnucleation stage (100 °C), quantum dots (QDs) developed. The production of dMSC-427 or QDs is hypothesized to be related to the solubility of the Cd precursor, such as Cd(OA)(OAc) or Cd(OA), respectively. Also, the reactions that lead to Cd(OA)(OAc) are proposed. The present study provides an in-depth understanding of the two-pathway model proposed for the prenucleation stage of binary colloidal QDs, as well as of the formation of MSCs and/or QDs.