Transformation of ZnS Precursor Compounds to Magic-Size Clusters Exhibiting Optical Absorption Peaking at 269 nm.

We report our investigation on the transformation pathway from precursor compounds (PCs) to magic-size clusters (MSCs) for semiconductor ZnS. We show, for the first time, a synthetic approach to ZnS MSCs in a single-ensemble form exhibiting optical absorption peaking at 269 nm. We thus symbolize the MSCs as MSC-269. The synthesis was performed with zinc oleate (Zn(OA)2) and elemental sulfur (S) as the respective Zn and S sources and 1-octadecene (ODE) as the reaction medium. Prior to the addition of S, oleylamine (OLA) is mixed with Zn(OA)2. ZnS MSC-269 evolved at a relatively high temperature from a reaction mixture or at room temperature during a dispersion incubation of a reaction product in a solvent. Both optical absorption and NMR studies support that the evolution of colloidal semiconductor MSCs contains three different stages. The present study narrows our knowledge gap on PC-to-MSC transformations that involve a loss of ligands from the PC.