Title page for etd-0701117-213645


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URN etd-0701117-213645
Author Tzu-Hsuan Yang
Author's Email Address No Public.
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Department Electro-Optical Engineering
Year 2016
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Study of Azo-POSS doped Liquid Crystals and Associated
Applications
Date of Defense 2016-08-22
Page Count 79
Keyword
  • pretilt angle
  • nanoparticle
  • azo-dye
  • liquid crystal
  • phase modulator
  • Abstract Liquid crystal is applied for numerous devices due to its anisotropy. However, if liquid crystal has chaos order, it will be regarded as an isotropic material. Therefore, surface alignment is crucial for almost all liquid-crystal applications. In this study, we use polyhedral oligosilsesquioxane (POSS) linked with eight group of azo-benzene mesogens to control the pretilt angle of liquid crystal. Under ultraviolet irradiation (λ = 365 nm), the Azo-POSS undergoes multiple configurational transformation from the fully-trans state (8 trans azobenzenes) through an intermediate (trans-cis-mixed) state to the fully-cis state, while the back-isomerization process can be activated by blue irradiation (λ = 450 nm). Under ultraviolet-blue dichromatic illumination, the Azo-POSS can be stabilized at any of the aforementioned states depending on the light-mixing ratio, thereby determining the dispersion behavior of the Azo-POSS nanoparticles in a nematic liquid crystal. As the result, we can control the pretilt angle of liquid crystal ranging from 0° to 90°. Furthermore, the optical phase modulator made of azo-POSS has high stability. It can remain a phase for 50 minutes and switch up to 50 times. The resolution of the device is 30μm. Hence, a photo-tunable and high-stability phase modulator was demonstrated. In addition, the temperature dependence of pretilt angle has been examined at different illumination conditions.
    Advisory Committee
  • Shie-Chang Jeng - chair
  • Chin-Ping Yu - co-chair
  • Ko-Ting Cheng - co-chair
  • Tsung-Hsien Lin - advisor
  • Files
  • etd-0701117-213645.pdf
  • Indicate in-campus at 5 year and off-campus access at 5 year.
    Date of Submission 2017-08-01

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