Li Xiaoshuai, Guo Yuqiang, Zhang Meishan, Zhang Chi, Niu Rui, Ma Hongmei, Sun Yubao
School of Electronic and Information Engineering, Hebei University of Technology, Tianjin 300401, PR China.
School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, PR China.
ACS Appl Mater Interfaces. 2023 Feb 8;15(5):7184-7195. doi: 10.1021/acsami.2c17770. Epub 2023 Jan 26.
Bistable polymer-stabilized cholesteric liquid crystal (LC) devices have been extensively researched due to their energy-saving benefits. Compared to devices with merely transparent and light-scattering states, LC devices with controlled light absorption or changeable color functions are unquestionably more intriguing. In this paper, a polymer-stabilized ion-doped cholesteric LC and an electrochromic layer are used to fabricate a colorable device which can show four operating states: transparent, light-scattering, colored transparent, and colored light-scattering. The working principle and fabrication strategy are explained in detail. Based on the dielectric response of LC, the electrohydrodynamic effect of ion-doped LC, and the redox reaction of electrochromic materials, the transparent or light-scattering state and the colored or colorless state of the device can be regulated by controlling the alternating frequency and the direction of the electric field. The display performance related to the monomer, chiral dopant, and electrochromic layer is investigated. The content of monomer and chiral dopant affects the polymer network and pitch of cholesteric LC, which then affects the driving voltages and contrast ratio. The thickness of the electrochromic layer has a significant impact on the transmittance of the device's coloring and fading states. The sample with excellent operating states is obtained by optimizing the material and the construction, which can be widely applied in smart windows and energy-saving display devices.
双稳态聚合物稳定胆甾相液晶（LC）器件因其节能优势而受到广泛研究。与仅具有透明和光散射状态的器件相比，具有可控光吸收或可变颜色功能的液晶器件无疑更具吸引力。本文利用聚合物稳定的离子掺杂胆甾相液晶和电致变色层制备了一种可呈现四种工作状态的可变色器件：透明、光散射、彩色透明和彩色光散射。详细解释了其工作原理和制备策略。基于液晶的介电响应、离子掺杂液晶的电流体动力学效应以及电致变色材料的氧化还原反应，通过控制交变频率和电场方向可以调节器件的透明或光散射状态以及彩色或无色状态。研究了与单体、手性掺杂剂和电致变色层相关的显示性能。单体和手性掺杂剂的含量会影响聚合物网络和胆甾相液晶的螺距，进而影响驱动电压和对比度。电致变色层的厚度对器件着色和褪色状态的透过率有显著影响。通过优化材料和结构获得了具有优异工作状态的样品，可广泛应用于智能窗户和节能显示器件。
