Professor Young-Hoon Kim and researcher Ji-Geon Kim of the Department of Applied Chemistry, College of Science and Technology, Kookmin University (President JEONG, SEUNG RYUL), and Professor Gon-Jae Ko of the Department of Chemical Engineering, Hanyang University, recently published a paper titled “SN2-mediated decoupled precursor provision enables large-scale production of monodisperse lead halide perovskite quantum dots in a single reactor” in the latest issue of the SCI international journal Advanced Composites and Hybrid Materials. The journal is a prestigious international journal that covers the latest research in the field of composite materials, and has an impact factor of 23.2, ranking in the top 2.9% of JCR-rated journals in the field.

Perovskite nanocrystals have excellent photophysical properties such as high luminous efficiency, wide color gamut, and high color purity, and are attracting attention as next-generation materials that will replace existing inorganic semiconductor quantum dots and organic light emitting diodes in next-generation displays and optoelectronic devices. However, the existing precursor injection-based synthesis method uses the PbX2 precursor of ionic bonding, which causes the framework of the [PbX6]4- octahedron structure to be formed in advance during the synthesis process, which limits precise control of nucleation and crystal growth. In particular, the synthesis parameters such as temperature and concentration gradient that occur during the precursor injection stage significantly reduce uniformity during mass production, and there are limitations to the stable production of high-quality and high-uniformity perovskite nanocrystals.

To solve this problem, Professor Young-Hoon Kim's research team developed a non-injection synthesis method based on a precursor conversion reaction. The research team used a bimolecular nucleophilic substitution reaction that converts a covalent precursor into a halide reactant to precisely control the nucleation and crystal growth of perovskite nanocrystals. The precursor conversion method using a nucleophilic substitution reaction minimized the influence of synthetic variables and maximized the uniformity of size and shape. It also solved the problems of nuclear generation control that occur in the conventional injection synthesis method and the problem of unbalanced crystal growth due to the low formation energy of perovskite nanocrystals.

The proposed nucleophilic substitution-based synthetic method not only improves the size and dimensional uniformity of perovskite nanocrystals compared to the existing injection method, but also achieves higher photoluminescence quantum efficiency and narrower emission half-width at single quantum dot level. In particular, the precise control of nucleation and crystal growth processes was experimentally confirmed using various real-time spectroscopic and crystallographic analysis techniques, and it was demonstrated that the mass synthesis of highly uniform perovskite nanocrystals with red, green, and blue luminescence is possible through this method.

The results of this study are expected to contribute to the commercialization of next-generation displays and optoelectronic devices by enabling the mass production of perovskite nanocrystals with high color purity. In particular, the synthetic strategy developed in this study is not limited to the synthesis of perovskite nanocrystals, but can also be applied to various nanocrystalline materials that require precise control of nucleation and crystal growth, and is expected to make an important contribution to the development of mass production technologies for next-generation nanomaterials and composite materials.