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arXiv 2603.04641cond-mat.softphysics.app-ph
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电色显色手性铁电向列液晶

Electrochromic chiral ferroelectric nematic liquid crystals

Kent State University(肯特州立大学)

Md Sakhawat Hossain Himel, James T. Gleeson, Robert J. Twieg, Samuel Sprunt, Antal Jakli

AI总结:

本研究展示了通过电场沿螺旋轴调节铁电向列液晶反射颜色的可逆方法,并提出了解释该现象的理论模型,拓展了该类材料的理解与应用前景。

摘要:

手性向列液晶是一维光子带隙材料,其反射波长可通过温度进行良好调节,但仅能通过电场实现有限且不可逆的调节。相比之下,斜向螺旋手性向列材料在沿螺旋轴施加<1kV/mm电场时会出现蓝移,而手性铁电向列液晶在垂直于螺旋轴施加<0.1kV/mm电场时可出现红移。在此,我们证明在铁电向列液晶中,沿螺旋轴施加电场也能实现反射颜色的可逆调节。在由裸露导电氧化铟锡(ITO)基板组成的夹层细胞中,电场强度高达0.4kV/mm时,反射峰波长可增加高达200nm。当ITO基板涂覆有电绝缘聚合物层时,反射率变化被抑制。我们提出一个理论模型,假设在电场作用下螺旋轴发生螺旋形变形。该模型能够解释所有观察到的现象,并且还估算出splay弹性常数,这通过其他方法难以确定。我们的发现扩展了对铁电向列液晶的理解,并建议在可调反射器和节能智能窗中具有潜在应用。

英文摘要:

Chiral nematic liquid crystals are one-dimensional photonic band-gap materials whose reflection wavelength can be well tuned by temperature, but only limited and irreversible tuning can be achieved by electric fields. In contrast, oblique heliconical chiral nematic materials blueshift with <1kV/mm fields applied along the helix axis, whereas chiral ferroelectric nematic liquid crystals can be redshifted by <0.1kV/mm fields applied perpendicular to the helix axis. Here we demonstrate that in ferroelectric nematic liquid crystals, the reflection color can be reversibly tuned also by electric fields applied along the helix axis. In sandwich cells assembled with bare conducting indium tin oxide (ITO) substrates, the reflectivity peak wavelength increases by up to 200 nm under fields up to 0.4 kV/mm. When the ITO substrates are treated with an electrically insulating polymer layer, the reflectivity shift is suppressed. We propose a theoretical model assuming helical deformation of the helix axis under electric field. This model accounts for all observations and also yields an estimate of the splay elastic constant which is challenging to determine by other methods. Our findings expand understanding of ferroelectric nematic liquid crystals and suggest potential applications in both tunable reflectors and energy-efficient smart windows.

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