Hierarchical Colloidal Self-Assembly on Lattice-Mismatched Moire Patterns

Extending atomic epitaxy concepts to colloidal systems for realizing functional surface structures has recently piqued scientific interest. Akin to the growth of ordered metal clusters on graphene moire, spatially ordered colloidal crystals have been realized on soft lithographically fabricated moire patterns. In addition to moire periodicity, lattice misfit strain can bring about a further level of hierarchy in colloidal self-assembly, although its role in self-organization remains unexplored. Here, we demonstrate the self-organized growth of micrometer-sized colloidal pyramid arrays with lateral order extending over millimeter length scales on lattice-mismatched moire patterns. By probing the film growth dynamics with single-particle resolution, we uncovered the interplay between lattice misfit strain and topographically varying surface potential within the moire unit cell, which significantly alters the nucleation process. We also show that the structural organization of colloids within moire regions primarily depends on the moire angle, and by tuning it, multiple levels of hierarchy can be achieved.