Self-assembled colloidal diamond

A lattice of spherical particles made of dielectric materials and arranged in an inverse diamond lattice has long been predicted to have a wide bandgap that is also robust to disorder in the material. However, making such an assembly of colloidal particles arranged into a diamond lattice is far from straightforward, owing to the energetic similarities between cubic and hexagonal diamond lattices. Now, David Pine and colleagues use precursor clusters of particles with carefully placed ‘sticky patches’—which attract and hold together adjacent clusters in specific geometries—to generate a self-assembled cubic diamond crystal. This can be used to template formation of an inverse diamond lattice, which calculations show to have the predicted wide bandgap.