Investigating the role of magic size clusters in the growth of InP quantum dots Theodore Anthony Gazis , Peter Matthews, Ashleigh Cartlidge Keele University, UK From light emitters inside cutting edge televisions to energy converters in photovoltaic cells, few compounds come close to the diversity of applications quantum dots (QDs) enjoy. The reason is rather simple. They constitute modular complexes, whereupon subtle changes in their size can dramatically alter their properties. This allows them to readily adapt to new demands. 1 Of particular interest are Indium Phosphide (InP) QDs which are entering a golden age due to their excellent optoelectronic properties and their lower toxicity relative to other QDs. 2 However, their greatest strength is also their Achilles heel. Their highly covalent nature necessitates reactive precursors to constrain the reaction window and encourage monodispersity. 2 Unfortunately, recent mechanistic studies have shed doubt on the ability of precursors to influence the growth regime and monodispersity of QDs. Instead, magic size clusters (MSCs) are thought to play a key role. 3 (Fig. 1) Fig. 1 Growth of QDs highlighting the intermediate MSCs. These clusters possess a specific number of atoms that confers them with particularly stable electronic and geometric structures. Indeed, certain examples have been shown to be stable up to 400 °C thus interfering with QD formation. 3 Despite their importance MSC isolation remains elusive. Only a handful are literature known and their conversion to QDs is poorly understood. The Matthews group is keen to bridge this gap. The protocol we have developed utilizes commercially available Ph 2 PSiMe 3 as an effective growth promoter. Adjusting the ratio of it in the reaction mixture allowed for nanoparticles to be isolated with UV signatures of 430, 450, 470 and 490nm. Remarkably, the above system was receptive to growth at 100 °C using volatile toluene as the reaction solvent. These results were published in Chemical Communications. 4 (Fig. 2) Fig. 2 Increasing equivalents of Ph 2 PSiMe 3 facilitates leads to larger MSCs. More recent results have shown judicious choice of the sterics and electronics of the aryl phosphine have a large influence on the optoelectronic properties of the QDs. Indeed, an extensive substate scope has been carried out uncovering more information on these crucial intermediates. References 1. A. Cotta ACS Appl. Nano Mater., 2020, 3 , 4920. Xu , S. Zeng , B. Zhang , M. T. Swihart , K. T. Yong and P. N. Prasad , Chem. Rev., 2016, 116 , 12234. 2. C. Gary,M. W. Terban,S. J. L. BillingeandB. M. Cossairt, Chem. Mater. , 2015, 27 , 1432. 3. A. Gazis, P. D. Matthews, Chem. Commun. , 2022, 58 , 13799.
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