Softness-Enhanced Self-Assembly of Pyrochlore- and Perovskite-like Colloidal Photonic Crystals from Triblock Janus Particles

Abstract

It remains extremely challenging to build three-dimensional photonic crystals with complete photonic bandgaps by simple and experimentally realizable colloidal building blocks. Here, we demonstrate that particle softness can enhance both the self-assembly of pyrochlore- and perovskite-like lattice structures from simple deformable triblock Janus colloids and their photonic bandgap performances. Dynamics simulation results show that the region of stability of pyrochlore lattices can be greatly expanded by appropriately increasing softness, and the perovskite lattices are unexpectedly obtained at enough high softness. Photonic calculations show that the direct pyrochlore lattices formed from overlapping soft triblock Janus particles exhibit even larger photonic bandgaps than the ideal nonoverlapping pyrochlore lattice, and proper overlap arising from softness can also dramatically improve the photonic properties of the inverse pyrochlore and perovskite lattices. Our study offers a new and feasible self-assembly path toward three-dimensional photonic crystals with large and robust photonic bandgaps.

Colloidal cubic diamond photonic crystals through cooperative self-assembly

“…45 As suggested in ref. 45 and 52, θ κ m = 65° is a suitable size of the patch for the TJPs to assemble to form the pyrochlore lattice featured by vertex-shared tetrahedra. So, θ κ m = 65° is chosen in our simulations.…”

“…Excitingly, recent theoretical investigations have predicted that an entropy-favored pyrochlore lattice could be self-assembled from simple and experimentally realizable triblock Janus particles (TJPs) with two attractive patches. 44–52 Therefore, it can be inferred that it might be possible to promote the formation of a cubic diamond lattice contained in a C15 superlattice via cooperative self-assembly of TJPs and isotropic colloidal spheres (CSs).…”

Multiple 2D crystal structures in bilayered lamellae from the direct self-assembly of 3D systems of soft Janus particles

“…The self-assembly of much harder Janus particles with α R ij = 39 996 as in ref. 39 is also investigated, and only the triangular lattice is obtained within the layers (Fig. S6, ESI†), which has been observed in 2D systems.…”

“…26,33,37,38 In fact, as suggested in ref. 39, the magnitude of α R ij controls the softness of the Janus particles, and the SJPs become harder and harder with increasing α R ij . The adhesion energy between the patches G ≈ 4.00 k B T ( i.e.…”

Soft matter crystallography -- complex, diverse, and new crystal structures in condensed materials on the mesoscale

“…Finally, deformable triblock Janus colloids selfassembled open structures, which were described via their relationships to crystal structures with ionic bonding character: a scaffold of vertex-sharing tetrahedra, sometimes termed the "pyrochlore" structure, which consists of only the Cu-sites in the cF 24-MgCu 2 Laves phase structure type or only the O-sites in the cF 24-SiO 2 cristobalite structure type 151 -the same structure was also observed in simulations of particles interacting via a repulsive square-shoulder pair potential. 152 Triblock Janus colloids also formed a scaffold of vertex-sharing octahedra, which consists of only the O-sites of the cP 5-CaTiO 3 perovskite structure type.…”