Entropic, Enthalpic, and Kinetic Aspects of Interfacial Nanocrystal Superlattice Assembly and Attachment

The combination of self-assembly and directed attachment of colloidal nanocrystals at fluid interfaces presents a scientifically interesting and technologically important research challenge. Remarkable strides have been made in the synthesis of polyhedral nanocrystals with precisely defined shapes and their self-assembly into highly ordered superstructures. We discuss the interplay of entropic and enthalpic driving forces and the kinetic aspects of interfacial self-assembly and attachment. We present in situ parallel small-angle X-ray scattering measurements and emerging insights into the complex choreography of interfacial transport processes involved in the formation of highly ordered epitaxially connected nanocrystal solids. New understanding emerging from in situ measurements provides process control and design principles for the selective formation of specific superlattice polymorphs. We discuss outstanding challenges that must be resolved to translate know-how from controlled assembly and attachment in the laboratory to scalable integration for emerging technological applications.