Prenucleation Clusters Assisting Development of Two Photoluminescent CdTeS Magic-Size Clusters with Optical Absorption Doublets.

Chemical self-assembly based evolution of magic-size clusters (MSCs) is proposed for the first time for photoluminescent (PL) ternary MSCs. In a mixture of cadmium oleate (Cd(OA)2), tri-n-octylphosphine telluride (TeTOP), bis(trimethylsilyl) sulfide ((TMS)2S), and acetic acid (HOAc), two types of PL CdTeS MSCs developed. They display optical absorption doublets peaking at 377/427 nm and 450/510 nm, and are denoted as MSC-427 and MSC-510, respectively. We suggest that the individual Cd, Te, and S containing molecules experience the process of chemical self-assembly that results in the formation of prenucleation clusters (PNCs) of CdTeS; relatively high feed concentrations of E (Te or S) and molar ratios of Cd-E are more favorable for the PNC formation. The PNC isomerizes to MSC-427 and is the precursor compound PC-427. PC-427 transforms into PC-510 via monomer addition, and PC-510 isomerizes to MSC-510. Our work brings a deeper insight into the evolution pathway of PL MSCs.