A UV‐Responsive Multifunctional Photoelectric Device Based on Discotic Columnar Nanostructures and Molecular Motors

Abstract

Orientation control of ordered materials would not only produce new physical phenomenon but also facilitate the development of fancy devices. Discotic liquid crystals (DLCs) form 1D charge transport pathway by self‐organizing into columnar nanostructures via π–π stacking. However, controlling the electrical properties in such nanostructures with some direct and instant way is a formidable task for their high viscosity and insensitivity to external stimuli. Herein, the arbitrary control over electrical conductivity of such columnar nanostructures is achieved with UV light by incorporating DLCs with molecular motors. Highly ordered DLC microstripe arrays are generated on desired substrate through a capillary bridge dewetting strategy. The conductivity of the microstripes could be continuously modulated by 365 nm light due to the influence of molecular motion under UV irradiation on the electron orbital overlap of columnar nanostructures. This is so because the disorder degree of the DLC molecules is associated with the intensity of UV light and the doping concentration of molecular motors. Moreover, the device shows memory effect and reversible conductivity change. The DLC microstripe arrays are very promising for the applications in UV detectors, memory devices, optical switches, and so on.

Influence of Coulombic Interaction on the Interfacial Self-Assembly of Discotic Liquid Crystal Amphiphiles: A Combined Experimental and Computer Simulation Study

“…11,12 Currently, the self-assembly properties of DLCs are a hot topic of research because of the unique charge-and energy-transport properties that offer huge possibilities for developing quantum conductive devices. 13 Among various noncovalent interactions such as van der Waals, entropic, steric, electrostatic, hydrophobic/hydrophilic, and hydrogen bonding, the π-stacking interaction is thought to be predominant particularly for the DLC systems. 14 Incorporation of an amphiphilic character by attaching suitable polar head groups offers further tunability of self-assembly properties at interfaces.…”

“…Interestingly, DLCs with an interlayer spacing of 0.34 nm have been regarded as a chemically synthesized version of DNA-mimic . Moreover, hybrid structures of DLC–DNA complexes have been reported in the bulk as well as at interfaces. , Currently, the self-assembly properties of DLCs are a hot topic of research because of the unique charge- and energy-transport properties that offer huge possibilities for developing quantum conductive devices …”

Visible-Light-Driven Rotation of Molecular Motors in a Dual-Function Metal–Organic Framework Enabled by Energy Transfer

“…Development of artificial molecular machines and motors allows for the design and construction of tailor-made molecular architectures capable of executing precisely controlled nanoscale structural motion. − Among these artificial systems, overcrowded alkene-based molecular motors attract considerable attention due to their chirality controlled photochemically driven repetitive unidirectional rotary motion. − Although it has been demonstrated that these molecules can perform various tasks in solution, such as control over the stereochemical outcome of catalytic reactions, Brownian motion precludes the cooperative action required to achieve functions beyond molecular dimensions. ,,, Achieving ensemble action with artificial molecular machines therefore requires that the randomizing effects of the thermal motion are eliminated by assembly on surfaces − or integration into the larger systems . Incorporation and immobilization of these molecules in various supramolecular architectures, including organo- and hydrogels, , polymers, , liquid crystals, − or self-assembled monolayers, − provided a way to amplify and harness their light-induced rotational motion to form responsive materials with tunable properties, including adaptive polymers, ,,, artificial muscles, , and responsive surfaces . For overcrowded alkene-based materials the use of UV light to drive the molecular motion limits such efforts due to limited penetration depth (due to the scattering) and potential damage by destructive photochemical processes. ,, Therefore, development of reliable and practical visible-light excitation strategies that are compatible with a chosen material represents a major challenge crucial for further advancement of these dynamic systems.…”

Exploration of elastomeric and polymeric liquid crystals with photothermal actuation: A review

“…Conflict between chirality and positional order of smectic phase is compromised when layers clubs together in form of twist grain boundary and each boundary displays rotation in helix form which also resembles screw dislocation. These can further be grouped to TGBP-A, C and C-chiral based on smectic phase present for transition [7,[23][24][25][26]. Ferroelectric LC owing to pre-occupied polarization (groups with dipole moment e.g.…”

“…These switches displayed intensified conductivity with 4 mW/cm2 UV but it ceased with >16 W/cm 2 UV ascribable to disturbed columnar alignment. In addition, LC evinced dual property of self-healing and memory device (>16 mW/cm 2 ) in which both can be activated by UV illumination (200 mW/cm 2 ) followed by ~70 o C heating-cooling (also employed for erasing data) [25]. Trček et al had observed TGBP transiting amidst smectic A phase and cholesteric phase when gold nanoparticles with dimensions in range ~10 nm was added in chiral CE8 LC.…”