Acta Chimica Sinica ›› 2020, Vol. 78 ›› Issue (6): 478-489.DOI: 10.6023/A20040103 Previous Articles     Next Articles



刘晓珺a, 秦朗a, 詹媛媛b, 陈萌c, 俞燕蕾a   

  1. a 复旦大学 材料科学系 聚合物分子工程国家重点实验室 上海 200433;
    b 华南师范大学 华南先进光电子研究院 响应型材料与器件集成国际联合实验室 广州 510006;
    c 复旦大学 材料科学系 上海 200433
  • 收稿日期:2020-04-09 发布日期:2020-05-08
  • 通讯作者: 俞燕蕾
  • 作者简介:刘晓珺,复旦大学材料科学系在读硕士生.2017年毕业于华南理工大学材料科学与工程系获学士学位.同年9月进入复旦大学材料科学系攻读硕士研究生,师从俞燕蕾教授.研究方向主要为功能性胆甾相液晶的构筑及其应用;俞燕蕾,复旦大学材料科学系教授,博士生导师.1993年毕业于安徽大学,1996年获中国科技大学硕士学位,同年进入复旦大学工作.2004年获得日本东京工业大学博士学位.2012年获得国家杰出青年科学基金.2016年受聘教育部"长江学者"特聘教授.2017年入选国家"万人计划"科技创新领军人才.2018年荣获中国化学会-赢创化学创新奖-杰出科学家奖.2019年荣获上海市自然科学奖一等奖(第一完成人).主要从事液晶高分子和光响应性材料的研究,利用其构筑光致形变材料、光致变色材料和光响应功能界面材料.
  • 基金资助:

Phototuning of Structural Colors in Cholesteric Liquid Crystals

Liu Xiaojuna, Qin Langa, Zhan Yuanyuanb, Chen Mengc, Yu Yanleia   

  1. a Department of Materials Science, State Key Laboratory of Molecular Engineering of Polymers, Fundan University, Shanghai 200433;
    b South China Academy of Advanced Optoelectronics, SCNU-TUE Joint Lab of Device Integrated Responsive Materials(DIRM), South China Normal University, Guangzhou 510006;
    c Department of Materials Science, Fundan University, Shanghai 200433
  • Received:2020-04-09 Published:2020-05-08
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Nos. 51903053, 21734003, 51721002), the National Key R&D Program of China (No. 2017YFA0701302), the Innovation Program of Shanghai Municipal Education Commission (No. 2017-01-07-00-07-E00027), and the China Postdoctoral Science Foundation (Nos. 2019T120300, 2018M641923).

Cholesteric liquid crystals (CLCs) are a kind of intriguing soft photonic crystal materials, in which the orientation of LC molecules varies in a helical fashion, and selectively reflect light, known as structural color, according to Bragg's law. Moreover, the structural color determined by the pitch length of the helices in CLCs can be tuned owing to the dynamic control of inherent self-organized helical superstructures in response to external stimuli. Currently, light-driven CLCs have attracted extensive interest because light, compared to other stimuli, has unique advantages of remote, temporal, local and spatial manipulation. Such elegant systems are generally formulated by doping light-driven chiral switches, mainly consisting of chiral centers and photoswitches, into a nematic LC host. The chiral centers are able to twist the nematic LC host into helical superstructures, which is represented by helical twisting power (HTP). The photoswitches undergo configurational changes upon photoisomerization, leading to the variation in HTP and the pitch length of the helices, and consequently tune the structural color of the CLCs. These light-driven CLCs provide opportunities for various photonic applications such as tunable filters, sensors, tunable optical lasers, and optically addressed displays. In this review, we summarize diverse light-driven CLC systems according to the type of the photoswitch in doped chiral switches. Azobenzene-and motor-based chiral switches usually have high HTP and large variation in HTP, which enables the tuning range of the resultant CLC to cover visible spectrum. Besides, chiral switches based on dithienylethenes have also been synthesized and utilized to tune the reflection of the CLC across red, green and blue colors that remain unchanged in darkness even after one week because of the excellent thermal stability of dithienylethenes. Chiral switches based on dicyanoethene are used to construct an optically tunable reflective-photoluminescent CLC system. Importantly, the design of the light-driven chiral switches is analyzed in detail to reveal the structure-property correlation. Potential and demonstrated practical applications of light-driven CLCs are discussed, and forecast of existing challenges and opportunities in CLC systems are concluded.

Key words: cholesteric liquid crystal, light-driven chiral switch, structural color, helical superstructure, azobenzene