Co-assembly of nanometer- and submicrometer-sized colloidal particles into multi-component ordered superstructures

Despite advances in computational chemistry and modeling, the discovery of new materials still remains largely empirical, often resembling an art rather than a precise science. A promising approach is to prepare superstructures from building blocks with intrinsic useful properties. Monodisperse nanometer- and submicrometer-sized colloidal particles, in particular, serve as versatile building blocks for this purpose. Their assembly has become a popular "bottom-up" method for creating superstructures. When two or more types of colloidal particles co-assemble, they form multi-component superstructures-often referred to as metamaterials-with diverse ordered arrangements and new properties emerging from synergistic interactions between the different particles. This review aims to systematically explore the co-assembly of two or more types of uniform nanometer- and submicrometer-sized colloidal particles into these multi-component superstructures. We also cover the fundamentals of particle assembly, including the development of uniform particles, maintaining their colloidal stability, and controlling the interparticle forces. Additionally, we discuss the kinetics of particle assembly, summarize the methods used to prepare particle superstructures, address defects that may occur, and provide an overview of their characterization techniques. Finally, we outline the challenges and opportunities in designing multi-component superstructures with ordered arrangements.