Fabrication of Photonic Bandgap Materials by Shifting Double Frameworks.

Biological organisms have evolved over millions of years to generate tremendously complex structures on a nanometer to micrometer scale. Among them, a range of three-dimensional (3D) biological photonic structures with minimal surface or constant mean curvature surfaces have been discovered in the wing scales of insects, attracting a great deal of interest because of their unique optical properties, such as structural color, antireflection, light collection, and photonic band gaps. Single-diamond and single-gyroid surface structures are considered to be excellent photonic crystals with complete band gaps. Although the corresponding bicontinuous architectures have been synthesized by self-assembly, single-framework structures are thermodynamically unfavorable and have been only achieved by physical fabrications and the alternating gyroid method. The production of materials derived from the thermodynamically stable double-framework structures provides a feasible solution for their chemical construction. This concept article highlights the significant progress in understanding 3D photonic structures by shifting double-frameworks to form low-symmetry structures, the physical properties of which can be greatly altered. Specifically, a complete photonic band gap can be achieved via a shifted double-diamond structure composed of materials with high dielectric contrast and high refractive index. We believe this concept will provide new insights in interdisciplinary research areas including the study of photonic structures, the self-assembly of amphiphilic molecules and the formation of biological architectures.