(244d) Short-Ranged Forces Enable the Self-Assembly of Binary Nanocrystal Superlattices

Binary nanocrystal superlattices are a new class of materials that incorporate two different kinds of nanocrystals within their structure. While their compositional flexibility and structural diversity leads to unique physical properties, our understanding of their self-assembly remains limited, particularly concerning the importance of interparticle interactions. Here we show that short-ranged attractive forces enable the self-assembly of two experimentally obtained structures. We demonstrate that these results stem from an increased thermodynamic driving force for self-assembly with short-ranged attraction relative to longer-ranged attraction or the purely repulsive interactions of the hard sphere model, leading to dramatic enhancement of the nucleation kinetics. We also explore the early stages of nucleation in our system, finding self-assembly to occur through classical, homogeneous nucleation. Our work represents important steps toward the a priori prediction of binary nanocrystal superlattice self-assembly.