There are several, disparate explanations in literature about the structure and the evolution of photoluminescent CdSe nano-species exhibiting sharp characteristic absorption doublets. In this presentation, I will report a comprehensive explanation of the evolution pathway from one CdSe magic-size clusters (MSCs) displaying an absorption doublet at 373/393 nm to another one with a doublet at 433/460 nm. Both MSCs are denoted as dMSC-393 and dMSC-460, respectively. Synchrotron-based small angle X-ray scattering (SAXS) suggests that the radii of gyration are 0.92 and 1.14 nm for dMSC-393 and dMSC-460, respectively, and both are disc-shaped with a Porod (P) factor close to 2. Thus, dMSC-393 is smaller than dMSC-460. Both dMSCs develop from their unique counterpart precursor compounds (PCs), which are labelled as PC-393 and PC-460, respectively. We hypothesize that the transformation from dMSC-393 to dMSC-460 occurs following a PC-enabled evolution pathway that is comprised of three key steps, dMSC-393 to PC-393 (Step 1), PC-393 to PC-460 (Step 2 involving monomer addition), and PC-460 to dMSC-460 (Step 3). The present study provides an in-depth understanding of the pathway of the evolution of MSCs exhibiting sharp absorption doublets, as well as their transformation.

Evolution pathway of CdSe magic-size clusters exhibiting sharp absorption doublets

ACS Fall 2021

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