Colloidal self-assembly: Superparticles get complex

The assembly of hundreds of thousands of semiconductor nanorods into nearly spherical or needle-like colloidal superparticles made of highly ordered supercrystalline domains can be explained by simple thermodynamic and kinetic principles. In fact, superparticles made of less than about 80,000 nanorods are double-domed cylinders, which consist of stacked multilayer disks of laterally packed nanorods sandwiched between two dome-shaped domains, themselves made of three supercrystalline domains: a central lamellar structure consisting of stacked multilayer arches of close-packed nanorods, and two small side domains formed by aligned nanorods. To better understand the principles governing the self-assembly forming the superparticles, Cao and co-workers visualized the constituent nanorods with a high-magnification transmission electron microscope.