Smart switchable windows for buildings and vehicles become more and more important because they can reduce energy consumption. They exhibit two optically contrasting states: a transparent state and an optically scattering (or light-absorbing) state. Most of them are, however, monostable, namely, only one of the optical states is stable in the absence of applied voltage, and the other state must be sustained under continuously applied voltage, which would consume energy. Here, we report a bistable smart window based on polymer-stabilized cholesteric liquid crystals. The window exhibits two stable states at 0 V: one of them is the transparent homeotropic state with a high transmittance and the other state is the scattering focal conic state with a low transmittance. The bistable states are achieved by using an anisotropic polymer network, known as polymer stabilization. The window is switched from the transparent state to the scattering state by a low-frequency ac voltage pulse under the flexoelectric effect and is switched from the scattering state back to the transparent state by a high-frequency ac voltage pulse under the dielectric interaction. No voltage is needed to sustain the two states of the window. Therefore, the window almost does not consume energy. The optical contrast between the two states is high, and the window is very efficient at privacy control. Due to its superior performance and very low energy consumption, this technology is expected to have a significant impact on switchable architectural and automobile windows.

中文翻译：

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基于挠曲电和介电效应的双稳态聚合物稳定胆甾型液晶窗

建筑物和车辆的智能可切换窗户变得越来越重要，因为它们可以减少能源消耗。它们表现出两种光学对比状态：透明状态和光学散射（或光吸收）状态。然而，它们大多数是单稳态的，即只有一种光学状态在没有施加电压的情况下是稳定的，而另一种状态必须在连续施加电压的情况下维持，这会消耗能量。在这里，我们报告了一种基于聚合物稳定胆甾液晶的双稳态智能窗。该窗口在0 V时表现出两种稳定状态：一种是高透过率的透明垂面态，另一种是低透过率的散射焦锥态。双稳态是通过使用各向异性聚合物网络实现的，称为聚合物稳定化。在挠曲电效应下，通过低频交流电压脉冲将窗口从透明状态切换到散射状态，并在介电相互作用下通过高频交流电压脉冲将窗口从散射状态切换回透明状态。不需要电压来维持窗口的两种状态。因此，窗户几乎不消耗能源。两种状态之间的光学对比度很高，并且窗口在隐私控制方面非常有效。由于其卓越的性能和极低的能耗，该技术预计将对可切换的建筑和汽车窗户产生重大影响。