Fabrication
of Well-Ordered Binary Colloidal Crystals
with Extended Size Ratios for Broadband Reflectance
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Abstract
Binary colloidal crystals (BCCs)
possess great potentials in tuning
material properties by controlling the size ratio of small to large
colloidal spheres (γ<sub>S/L</sub>). In this paper, we present
a method for the fabrication of BCCs with much more extended size
ratios than those obtained in conventional convective self-assembly
method. It is found that γ<sub>S/L</sub> can be extended to
0.376 by adding TEOS sol into the colloidal suspension. The resulting
polystyrene/silica (PS/SiO<sub>2</sub>) BCCs show distinctive reflections,
indicating their well-ordered structure. The extended size ratios
render more flexibility in engineering the photonic bandgap structures
of BCCs and hence provide a better platform for developing a range
of applications such as photonics, spintronics, sensing and bioseparation
