One-Step Approach to Single-Ensemble CdS Magic-Size Clusters with Enhanced Production Yields

Abstract

We report on the development of a single-step method to synthesize colloidal semiconductor magic-size clusters (MSCs) with an enhanced particle yield in a singleensemble form and free of the coproduction of conventional quantum dots (QDs). The present process eliminates the need for the second step of a lower-temperature incubation used in a two-step approach reported recently for the fabrication of single-ensemble MSCs without the contamination of QDs. We demonstrate that the combined use of a secondary phosphine (HPR 2) and an methyl carboxylic acid (RCH(CH 3)COOH, MA) promotes the yield of MSCs and suppresses the nucleation and growth of QDs. With CdO and elemental S powder as Cd and S sources, respectively, single-ensemble of CdS MSC-311 (displaying sharp absorption peaking at 311 nm) evolves directly in a reaction in 1-octadecene with enhanced production yield. The present study introduces a one-step avenue to synthesize effectively and selectively single-ensemble MSCs, and brings further understanding for the twopathway model proposed for the prenucleation stage of QDs.

Interplay between Perovskite Magic-Sized Clusters and Amino Lead Halide Molecular Clusters

“…In addition, PMSCs possess unique optical properties compared to PNCs such as bluer and sharper absorption and emission bands [ 22 , 23 ]. They are also important for understanding the underlying mechanisms of perovskite crystal growth [ 24 – 35 ]. However, one major challenge in the study of PMSCs is to determine their structure.…”

Room‐Temperature Formation Pathway for CdTeSe Alloy Magic‐Size Clusters

“…The present findings introduce a new approach to synthesizing alloy MSCs at room temperature by mixing binary induction period samples, and they enable further insight into the pathway for the room‐temperature formation of CdTeSe MSC‐399 with and without the complication of CdTe MSC‐371. Also, the present study provides a more complete understanding of the evolution of MSCs and the transformations among them . Similar to the fabrication of small‐size CdS quantum dots with enhanced particle yield from a CdS induction period sample, the room‐temperature synthesis of single‐ensemble CdTeSe MSC‐399 by mixing CdTe and CdSe induction period samples assists in the advance of nonclassical nucleation theory …”

“…Semiconductor binary II–VI metal chalcogenide (ME) magic‐size clusters (MSCs) in a single‐ensemble form, which are present without the complication of the coexistence of corresponding binary ME quantum dots, have recently been synthesized at room temperature from induction period samples of the binary ME quantum dots . The induction period precedes the time when quantum dots would have nucleated and grown, which is also called the prenucleation stage.…”

“…For II–VI ME, the respective composition of the latter two could be literally assumed to be M 2 E 2 and M n E n (with n >2) . The PC to MSC transformation (by intramolecular reorganization) has been demonstrated for CdTe MSC‐371, CdSe MSC‐415, CdS MSC‐311, CdS MSC‐322, ZnSe MSC‐299, and ZnS MSC‐269 . The MSCs are denoted in reference to their optical absorption peak positions in wavelength (nanometers).…”

“…We proposed that the evolution of CdTeSe MSC‐399 does not follow the combination of CdTe MSC‐371 and CdSe MSC‐415, but results from a particular CdTeSe PC by an intramolecular transformation, CdTeSe PC → CdTeSe MSC‐399 . This PC to MSC transformation resembles that of those binary ME MSCs . We also proposed that CdTeSe PC‐399 does not form by an addition reaction of CdTe PC‐371 and CdSe PC‐415 or by a partial anion exchange reactions [CdTe PC‐371 + SeTOP (tri‐n‐octylphosphine selenide) and CdSe PC‐415 + TeTOP (tri‐n‐octylphosphine telluride)].…”