Evolution of Two Types of ZnTe Magic-Size Clusters Displaying Sharp Doublets in Optical Absorption.

The two-pathway model proposed for colloidal semiconductor metal chalcogenide (ME) quantum dots (QDs) and magic-size clusters (MSCs) is demonstrated for ZnTe. Two new types of ZnTe MSCs have been found, which exhibit sharp optical absorption doublets peaking at 356/389 and 389/420 nm. Labeled dMSC-389 and dMSC-420, respectively, they were produced from reaction mixtures in 1-octadecene (ODE) of zinc oleate (Zn(OA)2), tri-n-octylphosphine telluride (TeTOP), diphenylphosphine (HPPh2), and acetic acid (HOAc, CH3COOH). The collective use of HOAc and HPPh2 enabled the exclusive production of dMSC-389 and dMSC-420 from reaction mixtures that had high Zn-to-Te feed molar ratios and a high Te feed concentration of 60 mmol/kg. The present findings demonstrate the utility of HOAc in synthesizing MSCs displaying a sharp absorption doublet, as well as of a secondary phosphine that decreases the temperature at which the M-E covalent bonds form.