Fig. 3: Assembly of a prescribed nanoscale analogue of a face-centred perovskite crystal structure using designed sets of mesovoxels with different degrees of information.
From: Encoding hierarchical 3D architecture through inverse design of programmable bonds
a, Left: a face-centred perovskite crystal can be designed using different mesovoxels. Middle: Mesovoxels 3 and 4, which encode different assembly information through voxels with different bond symmetries (structures shown on the left), are used to assemble face-centred perovskite crystals. Crystal formation is visualized by optical microscopy (empty crystal, left) and SEM imaging (right). Right: the face-centred perovskite structure of particles is confirmed through SAXS with the experimental S(q) shown for structures formed using Mesovoxel 3 (black) and Mesovoxel 4 (blue), with modelled S(q) (red). The associated diffraction peak locations are also shown. The SAXS data are normalized by the first peak position (q0) to account for the slight shift (<0.5 nm) in the lattice parameter due to sample-to-sample variations in divalent salt concentrations (see also control experiments in Supplementary Fig. 50). Peak positions were normalized by the centre of the first peak. b, TEM image after FIB sectioning, with green circles indicating NP positions. c–g, Experimental (black) and modelled (red) S(q) (Supplementary Figs. 31–38) with inset 2D SAXS patterns for structures with different layouts of occupied particle positions in Mesovoxel 4: corner only (c), faces only (d), centre only (e), corner and faces (f) and corner and centre (g). Corner only and centre only correspond to a simple cubic lattice with lattice parameters a = b = c = 118.2 nm and α = β = γ = 90°. Faces only corresponds to a body-centred tetragonal lattice with a = b = 83.6 nm, c = 118.2 nm and α = β = γ = 90°. Corner and faces corresponds to a face-centred cubic lattice with a = b = c = 118.2 nm and α = β = γ = 90°. Corner and centre corresponds to a body-centred cubic lattice with a = b = c = 118.2 nm and α = β = γ = 90°. The S(q) model for the perovskite design is based on face-centred perovskite unit cell with a = b = c = 118.2 nm and α = β = γ = 90°. h, Modelled crystal growth of a DNA scaffold demonstrates crystallization using equivalents of Mesovoxel 3 (left) and Mesovoxel 4 (middle), and a fully prescribed 27-voxel cell that shows no crystal formation (right). The accompanying plot shows the numbers of discrete clusters in the simulation versus the numbers of Monte Carlo simulation steps. Any free, unbound entity is designated as a single cluster.
