Department of Materials Science, State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai, 200433, China.
Adv Mater. 2018 Feb;30(8). doi: 10.1002/adma.201704941. Epub 2017 Dec 19.
Cholesteric liquid crystals (CLCs) exhibit selective reflection that can be tuned owing to the dynamic control of inherent self-organized helical superstructures. Although phototunable reflection is reported, these systems hitherto suffer from a limitation in that the tuning range is restricted to one narrow period and the optically addressed images have to sacrifice one color in the visible spectrum to serve as the background, resulting from the insufficient variation in helical twisting power of existing photoresponsive chiral switches that are all bistable. Here, delicate patterns of three primary red, green, and blue (RGB) colors with a black background are presented, which is realized based on piecewise reflection tuning of the CLC induced by a newly designed photoresponsive tristable chiral switch. Three stable configurations of the chiral switch endow the CLC with two continuous and adjacent tuning periods of the reflection, covering not only entire visible spectrum, but also one more wide period within near-infrared region. Therefore, the concept of piecewise tuning in CLC system demonstrates a new strategy for phototunable RGB and black reflective display.
胆甾相液晶（CLCs）表现出选择性反射，这种反射可以通过对固有自组织螺旋超结构的动态控制来进行调节。尽管已经有报道称可以实现光致可调反射，但这些系统迄今为止受到一个限制，即调谐范围仅限于一个狭窄的周期，并且光寻址图像必须牺牲可见光谱中的一种颜色作为背景，这是由于现有光响应手性开关的螺旋扭转能力变化不足所致，而这些开关都是双稳态的。在这里，提出了一种基于新设计的光响应三稳态手性开关诱导的 CLC 分段反射调谐，实现了具有黑色背景的三种基色（红、绿、蓝）的精细图案。手性开关的三种稳定构型赋予 CLC 两个连续且相邻的反射调谐周期，不仅覆盖整个可见光谱，还覆盖近红外区域内更宽的一个周期。因此，在 CLC 系统中的分段调谐概念为光致可调 RGB 和黑色反射显示展示了一种新策略。
