Iridescence in nematics: Photonic liquid crystals of nanoplates in absence of long-range periodicity

Abstract

Photonic materials with positionally ordered structure can interact strongly with light to produce brilliant structural colors. Here, we found that the nonperiodic nematic liquid crystals of nanoplates can also display structural color with only significant orientational order. Owing to the loose stacking of the nematic nanodiscs, such colloidal dispersion is able to reflect a broad-spectrum wavelength, of which the reflection color can be further enhanced by adding carbon nanoparticles to reduce background scattering. Upon the addition of electrolytes, such vivid colors of nematic dispersion can be fine-tuned via electrostatic forces. Furthermore, we took advantage of the fluidity of the nematic structure to create a variety of colorful arts. It was expected that the concept of implanting nematic features in photonic structure of lyotropic nanoparticles may open opportunities for developing advanced photonic materials for display, sensing, and art applications.

Colloidal Nanosurfactants for 3D Conformal Printing of 2D van der Waals Materials

“…Recently, 2D nanomaterials have garnered research interests owing to their promising electronic/optical properties. [ 6–9 ] For example, flexible thin‐film transistors printed with 2D nanomaterials inks including graphene (Gr), transition metal dichalcogenide (TMD), and hexagonal boron nitride (h‐BN) have been demonstrated. [ 10 ] In the past decade, organic solvents including ethanol, cyclohexanone, terpineol, and ethylene glycol have been extensively investigated for the printing of 2D nanomaterials; [ 4,5 ] however, limitations of organic solvents still exist due to their inherent toxicity, flammability, and poor biocompatibility.…”

Bio-inspired photonic crystal patterns

“…An iridescent structural colour pattern originates from a wellordered monodispersed latex assembly. [75][76][77][78][79][80][81][82][83] A noniridescent structural colour pattern originates from the breakage of a longrange ordered structure and assembly of a short-range ordered structure. 69,[84][85][86][87][88][89][90][91][92][93][94] Various processes are used for the preparation of short-range ordered structures for noniridescent structural colour patterns, such as spraying a mixture of two differentsized particles, 95 atomization deposition of a silica nanoparticle dispersion accompanied by an additive, poly(vinyl alcohol) (PVA), 24 and stretching the composite film to form short-range ordered nanovoids in the local strain region.…”

3D Chiral Photonic Nanostructures Based on Blue‐Phase Liquid Crystals

“…Liquid crystals combine the fluidity of conventional liquids and the ordering of crystals from molecular to macroscopic length scales and are considered one of the most promising materials for the development of large‐scale, high‐quality chiral photonic crystals. [ 44–55 ] Chiral liquid‐crystalline materials with inherent self‐organization ability are a promising candidate for the efficient, “green” and low‐cost production of photonic nanostructures with circular dichroism. The “softness” of liquid‐crystalline materials with tunable photonic bandgaps and robust responsiveness render them sensitive to various stimuli such as light, temperature, electric field, mechanical force, and chemical and electrochemical reactions.…”