Polymer-stabilized cholesteric liquid crystals as switchable photonic broad bandgaps
Polymer-stabilized cholesteric liquid crystals as switchable photonic broad bandgaps
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DOI：
10.1140/epje/i2004-10058-4
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发表时间：
2004-12-01
影响因子：
1.8
通讯作者：
Dessaud, N
中科院分区：
文献类型：
--
作者：
Mitov, M;Nouvet, E;Dessaud, N
双折射液晶可以被认为是一种一维光子晶体，由于分子的特殊排列，其折射率沿螺旋轴沿着规则地调制。其结果是，光的传播被抑制了特定范围的波长（带隙）。一种聚合物稳定的液晶（PSCLC），它是通过在原位光聚合的反应性液晶分子在定向布拉格平面纹理的非反应性液晶分子的存在下，通过结合UV固化与热诱导的间距变化，阐述。因此，它在这里示出的记忆效应被引入到在室温下的材料的反射带的特性。在可见光谱中，反射带宽可以与热斜坡一致地调谐并加宽。此外，带隙滤波器可以通过使它们经受电场而在宽带反射、散射和透明状态之间切换。这些功能材料的相关应用领域是用于控制太阳光谱的可切换智能窗户和无白色或黑色偏振器的反射式显示器。
A cholesteric liquid crystal can be considered as a one-dimensional photonic crystal with a refractive index that is regularly modulated along the helix axis because of the particular arrangement of the molecules. The result is that the propagation of light is suppressed for a particular range of wavelengths (bandgap). A polymer-stabilized cholesteric liquid crystal (PSCLC), which is obtained by in situ photopolymerization of reactive liquid-crystal molecules in the presence of non-reactive liquid-crystal molecules in an oriented Bragg planar texture, is elaborated by combining the UV-curing with a thermally induced pitch variation. As a consequence, it is shown here that memory effects are introduced into the characteristics of the reflection band of the material at room temperature. In the visible spectrum, the reflection bandwidth can be tuned in agreement with the thermal ramp and broadened. In addition, the bandgap filters can be switched between broadband reflective, scattering and transparent states by subjecting them to an electric field. Related application fields of these functional materials are switchable smart windows for the control of the solar-light spectrum and white-or-black polarizer-free reflective displays.