In this talk we describe the use of electric fields to drive nanocrystals assembly into superlattices. First, we demonstrate that field driven assembly can deposit well-ordered superlattices over large (cm<sup>2</sup>) areas. The process is amenable to wafer-level deposition, reversible and several orders of magnitude faster than conventional solvent evaporation or co-solvent techniques. Beyond creating a nanocrystal flux, we show that the electric field can be used to improve the polydispersity of the solution near the electrode, leading to higher crystalline quality. We use this improvement in crystal quality to probe nanocrystal-substrate interactions and show that the structure of nanocrystal superlattices can be switched from face centered cubic to body centered tetragonal by changing the hydrophobicity of the substrate. Although there have been several studies that show that superlattice structure can be altered by tuning the nanocrystal building block (core plus ligands) or solvent environment, we believe this is the first demonstration showing that superlattice structure can be dictated by the nanocrystal-substrate interaction alone. This adds a new tool for nanocrystal assembly that has not been harnessed before.<br/><br/>

Electric field-driven assembly of silver nanocrystal superlattices

2019 Spring National Meeting

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