A New Class of Chiral Nematic Phase with Helical Polar Order
A New Class of Chiral Nematic Phase with Helical Polar Order
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DOI：
10.1002/adma.202101305
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发表时间：
2021-07-18
影响因子：
29.4
通讯作者：
Araoka, Fumito
中科院分区：
文献类型：
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作者：
Nishikawa, Hiroya;Araoka, Fumito
通过在极性液晶中引入螺旋扭曲力，实现了一种具有极性螺旋有序的新型手性液晶相。诱导的极性Np（polar Np：Np*）相的性质不同于迄今存在的常规Np（N*）相的性质。Np* 是一类新的N* 结构，它不仅具有螺旋扭曲的指向矢，而且具有连续扭曲的极化。透射光谱和螺距测量在楔形细胞显示，在Np* 阶段的半螺距消失，因为在Np* 螺旋的极性响应。在介电和二次谐波产生研究中证实了Np* 相中的内极性指向矢。此外，这种独特的Np*LC对应于半/全螺距螺旋，能够实现超快电光开关（τ < 20 μ s），并为电可互换的光子带隙提出了新的潜在应用。
A novel chiral nematic phase with a polar helical order is realized via the introduction of helical twisting power into a polar nematogen. The properties of the induced polar nematic (polar cholesteric: Np*) phase differ from those of the conventional cholesteric (N*) phases existing thus far. Np*, which is a new class of N* structures, is characterized not only by its helically twisted nematic director, but also by a continuously twisted polarization. Transmission spectroscopy and helical pitch measurements in a wedge cell revealed that the half-helical pitch in the Np* phase vanished because of the polar response in the Np* helix. The inner polar director in the Np* phase is confirmed in dielectric and second-harmonic-generation studies. Furthermore, this unique Np*LC, which corresponds to a half-/full-pitch helix, enables ultrafast electro-optic switching (tau < 20 mu s), and proposes new potential applications for electrically interchangeable photonic bandgaps.