(662c) Seeded Growth of Shape-Controlled Wurtzite CdSe Nanocrystals: Cubes, Hexagonal Platelets, and Bullets

Previous investigations into the synthesis of wurtzite CdSe nanocrystals have given rise to well-developed methods for producing particles with anisotropic shapes such as rods, tetrapods and wires; however, the synthesis of other anisotropic shapes has proved challenging.  Here, we demonstrate the use of a seeded-growth approach to produce colloidal, shape-controlled wurtzite CdSe nanoparticles with previously unobserved morphologies.   The synthesis, which makes use of small CdSe nanocrystals as nucleation sites for subsequent growth, can be tuned to selectively yield colloidal CdSe cube- and hexagonal platelet-shaped nanocrystals, in addition to the previously observed rod- and bullet-shaped particles.  We characterize the structure and discuss possible growth mechanisms for these new shapes, and demonstrate a quantitative analysis technique for shape classification based on Fourier descriptors obtained from transmission electron micrographs.