Binary Colloidal Crystals Fabricated with a Horizontal Deposition Method

Abstract

We describe the use of a horizontal deposition method to prepare large-area binary colloidal crystals (bCCs). Two different sets of binary polystyrene spheres were employed to demonstrate the validity of this method. By varying the number ratios of small spheres with respect to large spheres, the stoichiometric configuration of the bCCs can be altered. Stable corresponding replica structures of the bCCs were also prepared, and the cross-sectional images of the binary inverse opals were obtained. Optical characterization demonstrated the presence of pseudostop bands, which were in agreement with the compositions of the material. The formation of the bCC by such a simple self-assembly method was attributed to the cooperative effect of interparticle electrostatic interactions and geometrical constrictions. This facile fabrication method further enhances the application potential of the bCCs and their inverse porous replicas with a binary pore system in the fields of photonics, solar cells, separations, catalysis, and biosensing.

Colloidal Assembly: The Road from Particles to Colloidal Molecules and Crystals

“…[20] A relatively fast and simple method for preparing largearea, multilayered binary colloidal assemblies involves a horizontal deposition process. [21] By varying both number and size ratios between large and small polystyrene (PS) spheres, different packing configurations have been achieved. All configurations consisted of an fcc lattice of large spheres containing small spheres in the interstitial spaces.…”

The Effect of Centrifugal Force on the Assembly and Crystallization of Binary Colloidal Systems: Towards Structural Gradients

“…First work on binary colloidal crystals has focused on spherical, charge-stabilized particles [32 -35]. Typically a face-centered cubic (fcc) structure of the larger spheres with different numbers of smaller spheres in octahedral or tetrahedral voids could be achieved [36]. A very successful method for the preparation of binary systems was presented in 2004 by Wang et al [37,38].…”

Non‐Brownian Particle‐Based Materials with Microscale and Nanoscale Hierarchy

“…Thef ormation of defects and cracks may develop due to the competition between the dense crystal structure formation versus the hydrodynamic pressure in the fluid evaporation process,n on-uniformity in particle size,o rc hanges in the orientational configuration (for example,aswitch between HCP and FCC). [18,30] Them ethods described herein can be extended for the creation of multicomponent crystals of varying g S/M/l ( Figure 2). Many combinations of triphasic crystals should be feasible provided that ag iven phase and its nearest comixture population are within the observed size ratio ranges that allow crystallization (for example, g S/M, g M/L 0.3, but > 0.1).…”

“…[16] In fact, in hard sphere (screen-charged) mixtures of nanoscale particles,ithas been observed that g S/L and N S/L determine whether the system attains as toichiometric or amorphous configuration. [1,13,[16][17][18][19] Many experimental studies show that bCCs can only be produced when 0.154 < g S/L < 0.225;h owever, simulation results suggest that 0.3 < g S/L < 0.41 should be possible. [3] Recently,C ai et al have experimentally expanded the working size ratio to g S/L = 0.376 through convective assembly to produce non-close packed binary crystals.…”