Superatoms in materials science

Abstract

Clusters are ensembles of bound atoms intermediate in size between a molecule and a bulk solid. Some of these clusters form stable units with atomically precise structures that give rise to collective behaviours that mimic those of traditional atoms, essentially functioning as ‘superatoms’. Such superatoms are exciting, nanoscale building blocks for materials design. Sustained synthetic and theoretical efforts over the past 40 years have created a vast library of chemically tuneable superatoms that display unique physical and chemical properties. The use of superatoms as building blocks for materials offers opportunities to design materials with tailored functionalities; however, this potential has only begun to be realized in the past few years. The assembly of superatomic crystals presents numerous challenges, including the design of suitable building blocks, control of the self-assembly process, promotion of strong inter-superatom coupling and understanding the resulting collective properties. In this Review, we assess recent advances in meeting these challenges by focusing on metal chalcogenide and carbon-based clusters (for example, fullerenes) as superatomic building blocks. Molecular clusters can be used as tuneable, superatomic building blocks to create new functional materials. This Review outlines the synthesis and assembly of superatoms into superatomic crystals and the resulting collective material properties.