Self-assembly of colloidal nanocrystals as route to novel classes of nanostructured materials

SummaryColloidal crystallisation is the only way to obtain three-dimensional ordered materials in which semiconductor, metallic, and magnetic nanocrystals are in close contact. It is expected that the quantum mechanical and dipolar interactions between the nanocrystal units can lead to unseen physical phenomena and materials. Here we review the development of this new and exciting field. We first compare nanocrystal superlattices with regular atomic solids regarding their mechanical strength and opto-electronic properties. We describe how nanocrystal superlattices have been obtained from colloid suspensions in several ways. The thermodynamic driving force for colloidal crystallisation is discussed in terms of inter-particle interactions in a good solvent and entropy. We compare the binary superlattices that have been obtained by solvent evaporation with the predictions of the hard-sphere model and show that semiconductor nanocrystals in a good solvent can behave as hard spheres. Finally, we discuss the quantum mechanical and dipolar interactions in nanocrystal superlattices and review recent studies of the opto-electronic and magnetic properties of novel superlattice materials.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (314 K)Download as PowerPoint slideHighlights► We review the differences between a nanocrystal superlattice and a regular atomic solid. ► We review the methods used to characterise the structure of nanocrystal superlattices. ► We review the methods to prepare nanocrystal superlattices and discuss the thermodynamic driving forces. ► We review collective electronic and magnetic properties of nanocrystals superlattices. ► We discuss the emerging applications of nanocrystal superlattices.