Lead author: Liulin Lv

Corresponding authors: Peng Xiaogang, Li Jiongzhao

Communication unit: Zhejiang University

Luminescent materials and academic QQ group: 529627332

The research background

In recent years, colloidal dot semiconductor nanocrystals (QDs) with three-dimensional quantum confinement have been widely studied due to their strong dimension-dependent emission properties and solution processability. After 40 years of extensive research, the comprehensive control of QDs size and size distribution has made great progress, but the research on point-like QDs with controllable facet is far from enough.

Results summary

Recently, Professor Peng Xiaogang and Li Jiongzhao of Zhejiang University reported that by using a two-step synthesis strategy, the synthesized CdSe QDs of blende have the expected symmetry, that is, the cubo-shaped QDs are wrapped on six equal (100) surfaces.

Figure 1. CdSe QDs of sphalerite.

Point 1: Preparation of cube QDs

Figure 2. Structural characterization of CdSe QDs.

Point 2: Growth mechanism

It was found that CdSe QDs had the narrowest ensemble photoluminescence (52 meV at half height and full width) due to its monodisperse size, unique facet structure and single crystallinity. In addition, by reducing the concentration of Cd(RCOO)2 as the sole ligand source at the nucleation stage, small sized CdSe quantum dots (≤3 nm) can be selectively formed as seeds, suitable for the growth of cubical quantum dots.

At the same time, the chloride ligand introduced in the soluble CdClx(RCOO)1−x(x= 0.1-0.2) form had poor nucleation effect, but it stabilized (100) crystal surface thermodynamically and accelerated Se ion deposition on (100) crystal surface kinetically.

Figure 3. Morphology evolution of nanocrystals.

summary

The results show that it is feasible to synthesize QDs with monodisperse size and surface structure by controlling nucleation and growth with ligands.

reference

Liulin Lv, et al, Monodisperse CdSe Quantum Dots Encased in Six (100) Facets via Ligand-Controlled Nucleation and Growth, J. Am. Chem. Soc, 2020

DOI: 10.1021 / jacs. 0 c06914

https://dx.doi.org/10.1021/jacs.0c06914

Source: Theory of Oddities

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