Jungwon Park

Direct observation of the formation, structures, and dynamics of individual colloidal nanocrystals

​Colloidal nanocyrstals are widely studied for their physical properties and utilized in biology, electronics, optics, and catalyst. However, most of nanocrystal synthesis and their uses are developed empirically with a limited mechanistic understanding. It is mainly because of their size and heterogeneity which cannot be easily accessible by conventional analytical methods. Here, we introduce in situ observations of the growth, 3D structures, and dynamics of individual nanocrystals by using liquid phase transmission electron microscopy. Our study unveils heterogeneity of growth mechanism of individual nanocrystals, critical steps during growth that incorporate non-classical pathways, and resulting 3D structures at the atomic resolution. Following their motions and interactions in solution, formation mechanism of the 2D superlattice of nanocrystals is also elucidated in a single particle resolution. Direct observation of nanocrystal motions when conjugated with biological systems is also presented along with an introduction of the methodological development that enables aforementioned studies.