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Materials (Basel). 2015 Sep 11;8(9):6071-6084. doi: 10.3390/ma8095293.

Optothermal Switching of Cholesteric Liquid Crystals: A Study of Azobenzene Derivatives and Laser Wavelengths.

Author information

1
Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University, Nantou 54561, Taiwan. s99328044@mail1.ncnu.edu.tw.
2
Graduate Program of Optoelectronic Technology, National Chi Nan University, Nantou 54561, Taiwan. Tanaka.Chen@auo.com.
3
Department of Medical Applied Chemistry, Chung Shan Medical University, Taichung 40201, Taiwan. jrchu@csmu.edu.tw.
4
Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University, Nantou 54561, Taiwan. kshsiao@ncnu.edu.tw.
5
Graduate Program of Optoelectronic Technology, National Chi Nan University, Nantou 54561, Taiwan. kshsiao@ncnu.edu.tw.

Abstract

The laser-initiated thermal (optothermal) switching of cholesteric liquid crystals (CLCs) is characterized by using different azobenzene (Azo) derivatives and laser wavelengths. Under 405-nm laser irradiation, Azo-doped CLCs undergo phase transition from cholesteric to isotropic. No cis-to-trans photoisomerization occurs when the 405-nm laser irradiation is blocked because only a single laser is used. The fast response of Azo-doped CLCs under the on-off switching of the 405-nm laser occurs because of the optothermal effect of the system. The 660-nm laser, which cannot be used as irradiation to generate the trans-cis photoisomerization of Azo, is used in Anthraquinone (AQ)-Azo-doped CLCs to examine the optothermal effect of doped Azo. The results show that the LC-like Azo derivative bearing two methyl groups ortho to the Azo moiety (A4) can greatly lower the clearing temperature and generate large amount of heat in AQ-A4-doped CLCs.

KEYWORDS:

anthraquinone dye; azobenzene; cholesteric liquid crystal; optothermal

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