Surface Ligands as Permeation Barrier in the Growth and Assembly of Anisotropic Semiconductor Nanocrystals.

Due to the large surface-to-volume ratio of colloidal nanocrystals (NCs), surfactant molecules grafted at NC surface play an important role on NC growth, interparticle interaction, processing and application. For this reason, much progress has been made in understanding the surface chemistry of NCs along with organic ligand shell particularly in terms of grafted polar group. However, most explanations on aliphatic counterparts are based on spherical NCs that usually have a dilute ligand layer. In anisotropic NCs such as nanorods and nanoplatelets, linearly extended dimension results in high-density aliphatic layer on the NC surface. Unlike spherical NCs, the compact organic shell could serve as a permeation membrane, effectively impeding a penetration of foreign molecules toward the NC surface. In this Perspective, we highlight the effects of ligand configuration on the properties of anisotropic NCs by exploring morphologies, assembled superstructures and surface reaction of anisotropic NCs.