Monodisperse Hexagonal Pyramidal and Bipyramidal Wurtzite CdSe-CdS Core–Shell Nanocrystals

Heterostructural core–shell quantum dots (hetero-QDs) have garnered a copious amount of research effort for not only scientific advances but also a range of technological applications. Particularly, controlling the heteroshell deposition, which in turn determines the particle morphology, is vital in regulating the photophysical properties and the application potential of the hetero-QDs. In this work, we present the first report on a synthesis of pyramidal shaped (i.e., hexagonal pyramid, HP, and hexagonal bipyramid, HBP) CdSe-CdS hetero-QDs with high morphological uniformity and epitaxial crystallinity through a two-step shell growth method. The stabilization of the exposed (0002) and {1011} facets by octadecylphosphonic acid and oleic acid ligands, respectively, is the key for the formation of pyramidal particle shapes. High photoluminescence quantum yield (94%, HP-QDs and 73%, HBP-QDs), minimal inhomogeneous PL line width broadening, and significantly suppressed single-QD blinking are observed. Specifi...