Hybrid Cholesteric Films with Tailored Polarization Rotation

Abstract

Incorporation of metal nanoparticles in chiral (Ch) films of cellulose nanocrystals (CNCs) enhances nanoparticle plasmon resonances, due to the coupling of the intrinsic properties of the plasmonic guest and the photonic properties of the Ch-CNC host. In contrast with previous reports, the properties of the Ch-CNC host are focused and an effective strategy is developed for tuning the optical polarization rotation of the composite films formed by the CNCs and gold nanoparticles. A twofold enhancement in the polarization rotation power of the composite Ch-CNC films, with an insignificant change in the incurred optical losses, is achieved by varying the density and dimensions of gold nanoparticles embedded in the Ch-CNC films. For such films, a new approach is developed to obtain broadband circular dichroism by fabricating films from mixtures of CNC suspensions ultrasonicated for different time intervals. These new findings enable fine-tuning of the power and spectral range of the polarization rotation and offer a novel strategy for the fabrication of broadband reflectors and polarizers, smart solar windows, and detectors for circularly polarized light.

Liquid Crystal Templated Chiral Plasmonic Films with Dynamic Tunability and Moldability

“…DOI: 10.1002/adfm.202111280 thin films exhibiting circular dichroism (CD) or circularly polarized luminescence have been widely studied to realize novel types of organic light-emitting diodes, polarizers, and organic field-effect transistors. [1][2][3][4][5][6] Meeting the requirements for particular applications requires tuning the chiroptical properties of the films, which is possible through a rational choice of building blocks and control over the symmetry and geometry of the film. Thus, it is not surprising that soft organic matter has been a primary choice, owing to its processability, self-assembly, and possibilities for mesoscopic morphology control.…”

Orientation Control of Helical Nanofilament Phase and Its Chiroptical Applications

“…HNF has the potential to be used as a template to induce chirality in achiral organic/inorganic materials because of its chiral shape and firmness [77][78][79][80][81][82][83]. If the chirality transfer succeeds in metal nanoparticles [84], fluorescence dye, and additional LC molecules, various chiroptical applications can be rationalized, for example, tailored polarization rotation [82], photonic metamaterial [85], chiral fluorescence [86], etc. Recently, various chiral templating applications have been studied.…”

“…The structure was investigated using TEM, atomic force microscopy (AFM), and XRD. Such a gold helix can be applied to chiroptical applications such as chiral plasmonic and metamaterials [82,85].…”

“…The structure was investigated using TEM, atomic force microscopy (AFM), and XRD. Such a gold helix can be applied to chiroptical applications such as chiral plasmonic and metamaterials [82,85]. According to a report by Jeon et al [46], when a bent-core LC molecule is mixed with a rodshaped LC molecule 4′-octyl-4-biphenylcarbonitrile (8CB), the HNF phase is formed first, followed by 8CB phase transition of the nematic and smectic phases.…”

Chiral Carbon Dots Synthesized on Cellulose Nanocrystals

“…Acid‐based hydrolysis of cellulose nanofibers yields whisker‐shaped 100–300 nm long cellulose nanocrystals (CNCs), which exhibit a right‐handed twist along their long axis . Furthermore, in aqueous suspensions CNCs form lyotropic left‐handed Ch nematic liquid crystals …”