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Feng X, Lu L, Yaroshchuk O, Bos P. Closer look at transmissive polarization volume holograms: geometry, physics, and experimental validation. APPLIED OPTICS 2021; 60:580-592. [PMID: 33690431 DOI: 10.1364/ao.412589] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 12/11/2020] [Indexed: 06/12/2023]
Abstract
In this work, we took a closer look at transmissive polarization volume holograms (T-PVH) to provide clarifications on their geometry, physics, and optical responses by finite-difference time-domain (FDTD) simulation and experimental validation. First, we introduced the four possible geometries of T-PVH and simulated their optical responses in terms of diffraction efficiency, polarization selectivity, and polarization output. It is shown that the configuration we called "Slanted T-PVH (B-θ/D-θ+90)," where the director is perpendicular to the Bragg planes, has the advantageous property of maintaining circular output polarization states. For this configuration, a detailed simulation of spectral, angular, and polarization responses was completed. Finally, we validated the FDTD simulation results of the Slanted T-PVH (B-θ/D-θ+90) structures with experiments.
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Lu H, Zhang X, Sakurai T, Li X, Tu Y, Guo J, Seki S, Li CY, Ungar G, Cheng SZD. Frustrated Layered Self-Assembly Induced Superlattice from Two-Dimensional Nanosheets. NANO LETTERS 2020; 20:8647-8653. [PMID: 33164515 DOI: 10.1021/acs.nanolett.0c03352] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Here we reported a hierarchical self-assembly approach toward well-defined superlattices in supramolecular liquid crystals by fullerene-based sphere-cone block molecules. The fullerenes crystallize to form monolayer nanosheets intercalated by the attached soft hydrocarbon cones. The frustration caused by cross-sectional area mismatch between the spheres and the somewhat oversize cones leads to a unique lamellar superlattice whereby each stack of six pairs of alternating sphere-cone sublayers is followed by a cone double layer. While such areal mismatch problems in soft matter are usually solved by interface curvature, the lamellar superlattice solution is best suited to systems with rigid layers. Meanwhile, formation of the superlattice significantly improves the material's transient electron conductivity, with the maximum value being among the highest for π-conjugated organic materials. The design principle of solving steric frustration by forming a superlattice opens a new avenue toward self-assembled optoelectronic materials.
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Affiliation(s)
- Huanjun Lu
- Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Xiaoyan Zhang
- College of Materials Science and Engineering, Qingdao University, Qingdao 266071, China
| | - Tsuneaki Sakurai
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Xiaohong Li
- Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Yingfeng Tu
- Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Jun Guo
- Testing and Analysis Center, Soochow University, Suzhou 215123, China
| | - Shu Seki
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Christopher Y Li
- Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Goran Ungar
- State Key Laboratory for Mechanical Behaviour of Materials, Shanxi International Research Center for Soft Materials, Xi'an Jiaotong University, Xi'an 710049, China
- Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom
| | - Stephen Z D Cheng
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
- Department of Polymer Science, College of Polymer Science and Polymer Engineering, University of Akron, Akron, Ohio 44325, United States
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Reppe T, Poppe S, Tschierske C. Controlling Mirror Symmetry Breaking and Network Formation in Liquid Crystalline Cubic, Isotropic Liquid and Crystalline Phases of Benzil-Based Polycatenars. Chemistry 2020; 26:16066-16079. [PMID: 32652801 PMCID: PMC7756378 DOI: 10.1002/chem.202002869] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Indexed: 12/25/2022]
Abstract
Spontaneous development of chirality in systems composed of achiral molecules is important for new routes to asymmetric synthesis, chiral superstructures and materials, as well as for the understanding of the mechanisms of emergence of prebiotic chirality. Herein, it is shown that the 4,4'-diphenylbenzil unit is a universal transiently chiral bent building block for the design of multi-chained (polycatenar) rod-like molecules capable of forming a wide variety of helically twisted network structures in the liquid, the liquid crystalline (LC) and the crystalline state. Single polar substituents at the apex of tricatenar molecules support the formation of the achiral (racemic) cubic double network phase with Ia 3 ‾ d symmetry and relatively small twist along the networks. The combination of an alkyl chain with fluorine substitution leads to the homogeneously chiral triple network phase with I23 space group, and in addition, provides a mirror symmetry broken liquid. Replacing F by Cl or Br further increases the twist, leading to a short pitch double gyroid Ia 3 ‾ d phase, which is achiral again. The effects of the structural variations on the network structures, either leading to achiral phases or chiral conglomerates are analyzed.
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Affiliation(s)
- Tino Reppe
- Institute of ChemistryMartin Luther University Halle-WittenbergKurt-Mothes-Straße 206120HalleGermany
| | - Silvio Poppe
- Institute of ChemistryMartin Luther University Halle-WittenbergKurt-Mothes-Straße 206120HalleGermany
| | - Carsten Tschierske
- Institute of ChemistryMartin Luther University Halle-WittenbergKurt-Mothes-Straße 206120HalleGermany
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