Stimuli‐Directing Self‐Organized 3D Liquid‐Crystalline Nanostructures: From Materials Design to Photonic Applications

Abstract

3D photonic nanostructures with desirable functionalities in the visible light region and beyond have been recently given vast and increasing attentions because of the ability to control or confine electromagnetic waves in all three dimensions. Although substantial progress has been made in fabricating 3D nanostructures by means of lithography and nanotechnology, various bottlenecks still need to be overcome, and developing soft 3D stimuli‐directed nanostructures with tailored properties remains a challenging but exciting work. In this context, soft nanotechnology—i.e., exploiting self‐organized soft materials in nanotechnology—is emerging as a vibrant and burgeoning field of research in the bottom‐up nanofabrication of intelligent stimuli‐driven 3D photonic materials and devices. Liquid‐crystalline materials undoubtedly represent such a marvelous dynamic system that combines the liquid‐like fluidity and crystal‐like ordering from molecular to macroscopic material levels. Importantly, being “soft” makes the materials responsive to various stimuli such as temperature, light, mechanical force, and electric and magnetic fields as well as chemical and electrochemical reactions, resulting in a fascinating tunability of dynamic photonic bandgaps in the 3D nanostructure that provides numerous opportunities in all‐optical integrated circuits and next‐generation communication systems. Here, the development of 3D photonic nanostructures is reviewed, culminating with perspectives for the future scope and challenges of these emerging soft 3D photonic nanostructures towards device applications.

Self-activating liquid crystal devices for smart laser protection

“…As is well-known, liquid crystals (LCs) represent a fabulous category of stimuli-responsive functional soft materials with an intermediate state between the isotropic liquid and the crystalline solid phases, therefore combining the fluidity of liquids and the orientational order of solids at different supramolecular and macroscopic levels [36][37][38][39][40][41][42][43][44]. Depending on the orientational order level of liquid crystalline components, LCs could exhibit a multitude of phases, such as nematic phase with only the orientational order, smectic phase with both the orientational and translational long range ordering, and chiral nematic phases including blue phases with periodic cubic nanostructure.…”

Two-photon lithography for 3D magnetic nanostructure fabrication

“…It is also difficult to envisage the fabrication of complex, extended 3D networks or geometries using this technique. In other disciplines, a range of selfassembly and chemical methods have resulted in great success in the fabrication of 3D nano/microstructures, including chiral liquid crystal structures [11,12] and hybrid 3D graphene/gold nanoparticle structures [13]. In addition, the manipulation of droplets upon surfaces via magnetic guiding and three-phase contact lines has been shown to be a powerful method to produce 3D microstructures in a number of geometries, including magnetic inks [14], CdTe quantum dots [15], silver nanoparticles [15], and manganese chloride salts [15].…”

Formation of Photo-Responsive Liquid Crystalline Emulsion by Using Microfluidics Device

“…There is a report on the formation of the LC droplet using this method [11]. Moreover, the color control of a cholesteric liquid crystal droplet with photoresponsive chiral dopant was reported, and the color ranged from blue to red [12,13], and also it was demonstrated for the lasing application [14]. By encapsulating this LC droplet with a polymer core, the coloring particle was successfully developed [15].…”