Ferroelectric nematic phase at and below room temperature

Manabe, Atsutaka; Bremer, Matthias; Kraska, Martin

doi:10.1080/02678292.2021.1921867

Cited by 100 publications

(92 citation statements)

References 13 publications

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“…Thin films obtained by casting without any thermal treatment were used as reference in order to evaluate the influence of the ordering on electrical conduction. As can be seen in Figure 2 , the ordered films presented intense birefringence, with a fine Schlieren texture, indicating a nematic mesophase in which the azomethine rigid mesogens were preponderantly aligned parallel to a local director [ 22 , 23 , 24 , 25 ]. The texture clarity was correlated to the percentage of mesogen in the polymer, with more resolved textures observed for polymers containing 75% ( P2 ) or 50% ( P3 ) mesogens.…”

Section: Resultsmentioning

confidence: 99%

Impact of the Liquid Crystal Order of Poly(azomethine-sulfone)s on the Semiconducting Properties

et al. 2022

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Organic semiconductors are an attractive class of materials with large application in various fields, from optoelectronics to biomedicine. Usually, organic semiconductors have low electrical conductivity, and different routes towards improving said conductivity are being investigated. One such method is to increase their ordering degree, which not only improves electrical conduction but promotes cell growth, adhesion, and proliferation at the polymer–tissue interface. The current paper proposes a mathematical model for understanding the influence of the ordering state on the electrical properties of the organic semiconductors. To this end, a series of aromatic poly(azomethine)s were prepared as thin films in both amorphous and ordered states, and their supramolecular and electrical properties were analyzed by polarized light microscopy and surface type cells, respectively. Furthermore, the film surface characteristics were investigated by atomic force microscopy. It was established that the manufacture of thin films from mesophase state induced an electrical conductivity improvement of one order of magnitude. A mathematical model was developed in the framework of a multifractal theory of motion in its Schrodinger representation. The model used the order degree of the thin films as a fractality measure of the physical system’s representation in the multifractal space. It proposed two types of conductivity, which manifest at different ranges of fractalization degrees. The mathematical predictions were found to be in line with the empirical data.

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Section: Resultsmentioning

confidence: 99%

Impact of the Liquid Crystal Order of Poly(azomethine-sulfone)s on the Semiconducting Properties

et al. 2022

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“…6a) which undergoes a direct Isotropic to NF transition. 37 Although the NF phase is monotropic, the melting point of this material is sufficiently low as to permit room temperature studies on the NF phase; below 20 °C the dielectric permittivity of the material is in excess of 20000. 37 Recently, Huang et al have reported two highly fluorinated rod-like mesogens which exhibit the NF phase (Figure 6b).…”

Section: Emerging Materials Classesmentioning

confidence: 99%

“…37 Although the NF phase is monotropic, the melting point of this material is sufficiently low as to permit room temperature studies on the NF phase; below 20 °C the dielectric permittivity of the material is in excess of 20000. 37 Recently, Huang et al have reported two highly fluorinated rod-like mesogens which exhibit the NF phase (Figure 6b). 38 As with all NF materials known to date, these materials feature polar groups (in this case, 1,3-dioxane, 2,5-difluorophenyl, nitrile) oriented in such a way to give a large longitudinal molecular electric dipole moment.…”

Section: Emerging Materials Classesmentioning

confidence: 99%

A New Order of Liquids: Polar Order in Nematic Liquid Crystals

Mandle

2022

Preprint

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Given the widespread adoption of display technology based on nematic liquid crystals, the discovery of new nematic phases at thermodynamic equilibrium, although extremely rare, generates much excitement. The remarkable discovery polar order and giant ferroelectric polarisation in a nematic fluid is a watershed moment in soft matter research, and is one of the most important discoveries in the 150-year history of liquid crystals. After a brief introduction to this emerging field, we present the current state-of-the art in terms of understanding the molecular origins of this phase, before exploring how molecular structure underpins the incidence of this phase, as well as exploring future directions.

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“…LCDs with response time in the range of microseconds are proper candidates for these applications. FLCs are characterized by response time in the range of microseconds due to the presence of the spontaneous polarization → P s (Figure 1) that canceled out in NLC due to symmetry [63][64][65][66]. Sensitivity to the electrical field sign also stems from the spontaneous polarization existence.…”

Section: Comparison Of the Electrooptic Response Of Nh-flcs With Nlcsmentioning

confidence: 99%

Helical Nanostructures of Ferroelectric Liquid Crystals as Fast Phase Retarders for Spectral Information Extraction Devices: A Comparison with the Nematic Liquid Crystal Phase Retarders

et al. 2021

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Extraction of spectral information using liquid crystal (LC) retarders has recently become a topic of great interest because of its importance for creating hyper- and multispectral images in a compact and inexpensive way. However, this method of hyperspectral imaging requires thick LC-layer retarders (50 µm–100 µm and above) to obtain spectral modulation signals for reliable signal reconstruction. This makes the device extremely slow in the case of nematic LCs (NLCs), since the response time of NLCs increases proportionally to the square of the LC-layer thickness, which excludes fast dynamic processes monitoring. In this paper, we explore two approaches for solving the speed problem: the first is based on the use of faster nanospiral ferroelectric liquid crystals as an alternative to NLCs, and the second is based on using a passive multiband filter and focuses on multispectral extraction rather than hyperspectral. A detailed comparative study of nematic and ferroelectric devices is presented. The study is carried out using a 9-spectral bands passive spectral filter, covering the visible and near-infrared ranges. We propose the concept of multispectral rather than hyperspectral extraction, where a small number of wavelengths are sufficient for specific applications.

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Ferroelectric nematic phase at and below room temperature

Cited by 100 publications

References 13 publications

Impact of the Liquid Crystal Order of Poly(azomethine-sulfone)s on the Semiconducting Properties

Impact of the Liquid Crystal Order of Poly(azomethine-sulfone)s on the Semiconducting Properties

A New Order of Liquids: Polar Order in Nematic Liquid Crystals

Helical Nanostructures of Ferroelectric Liquid Crystals as Fast Phase Retarders for Spectral Information Extraction Devices: A Comparison with the Nematic Liquid Crystal Phase Retarders

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