Luminescent materials and academic QQ group: 529627332

The size distribution and structure quality of quantum dots (QDs) have important influence on the optical and electrical properties of QDs. Although the synthetic strategy to control the size of QDs has been widely used in various QDs systems, the structural characteristics of QDs, such as morphology and crystallinity, are mostly regulated by trial and error.

Recently, Hee-Sun Han, University of Illinois at Urbana-Champaign, USA, reported the key parameters affecting the quality of nanocrystals, including crystallinity, morphology, defect density, and core-shell interface structure, and introduced a design guide for precursors that can systematically optimize growth conditions.

It is found that the reactivity and growth temperature of the precursor control the structure quality of nanocrystals. The growth temperature determines the instability degree of surface atoms, while the reactivity of precursors affects the reaction kinetics of QDs surface. These two parameters must be adjusted in a systematic way to produce highly crystallized spherical QDs with minimal defects and controllable core-shell structure.

The systematic changes in the reactivity of precursors challenge the existing precursors. The reactivity of traditional precursors is mainly determined by their chemical structure, and different molecules need to be synthesized to change the reactivity. In addition, in most cases, the existing selection of precursors covers only a narrow range of reactivity and therefore cannot induce controlled growth of QDs of different sizes and materials. To address this limitation, the researchers designed a sulfur precursor, BBN-SH, whose reactivity can be chemically regulated in a predictable manner. In combination with Lewis base (LB), BBN-SH contains a wide range of reactivity, allowing them to be used in QDs of different materials and sizes.

By monitoring the structural quality of QDs while varying the growth temperature and reactivity of the precursor, the researchers determined general guidelines for quantum dot growth conditions applicable to different sizes and materials. The results show that BBN-SH can be used as a universal precursor to systematically grow high-quality QDs of various sizes, different materials (CdS, PbS, CuInS2), and different types (nucleus and nucleus/shell), and the QDs obtained have the characteristics of high crystallinity, spherical shape, narrow emissition, high QY, good monodispersion, and clear interface structure of nucleus and shell, etc.

This work provides key insights into nanoparticle growth processes and precursor design, making it possible to systematically prepare high-quality QDs of any size and material.

Joonhyuck Park, et al, Controllable modulation of precursor reactivity using chemical additives for systematic synthesis of high-quality quantum dots, Nat Commun, 2020

DOI: 10.1038 / s41467-020-19573-4

https://doi.org/10.1038/s41467-020-19573-4

Source: Theory of Oddities

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