Title: Photostationary RGB Selective Reflection from Self-Organized Helical Superstructures for Continuous Photopatterning

Author: Lang Qin, Jia Wei, Yanlei Yu*

Journal: Adv. Optical Mater., 2019, 7(18), 1900430.

Abstract:

Light-driven cholesteric liquid crystals (CLCs) are intriguing materials due to the dynamic tuning of their selective reflection, which originates from self-organized helical superstructures, in response to light. However, CLC systems are restricted to displaying static optically addressed images and need to be initialized or refreshed before every new image can be displayed. Herein, a novel tuning mechanism based on a partial photochemical phase transition is proposed to enable continuous patterning of photostationary red, green, and blue (RGB) colors in a CLC system, which contains nonresponsive chiral dopants and o-fluoroazobenzenes (Fazo) to serve as the photoswitch. Distinct isomer ratios of Fazo result in precise light-directed RGB colors for the photostationary states, and, thus, a fixed relationship is established between the light stimulus and the reflection color. Accordingly, the RGB color patterns can be continuously erased and rewritten under light irradiation with different wavelengths. A photocontrollable “Tetris game” is demonstrated for the first time according to the programmable modulation of the CLC reflection, providing a new concept for optically rewritable displays.

论文链接：https://onlinelibrary.wiley.com/doi/10.1002/adom.201900430

PDF下载：Photostationary RGB Selective Reflection from  Self-Organized Helical Superstructures for Continuous Photopatterning.pdf

本文开发了一种基于部分光化学相变而不是螺旋扭曲力（HTP）变化的新方法来对胆甾相液晶（CLC）的反射进行编程，实现RGB颜色的连续图案化。我们将常用的光响应手性开关分成两个独立的简单结构，包括作为手性掺杂剂的联萘衍生物和作为光开关的邻氟偶氮苯（Fazo）。当掺杂到LC主体E7中时，联萘衍生物立即诱导螺旋超结构，Fazo在光异构化时发生构象变化，干扰LC排列并调整反射颜色。具有不同的异构体比例（反式/顺式：75/25、50/50和20/80）的Fazo有助于可见光谱中的全色调谐和光定向调制三种原色的RGB颜色。基于CLC反射的这种可编程调制，RGB颜色图案可以在不同波长的照射下连续擦除和重写。此外，我们展示了彩色图案甚至是可光控的“俄罗斯方块游戏”。