臺灣博碩士論文加值系統

本論文選擇介電異方性(Dielectric Anisotropy) 小於零之液晶材料，並添加適當螺旋強度(HTP) 之旋光性分子，產生溫寬約8.5 度且範圍涵蓋室溫之霧狀藍相(BPIII)。
從實驗結果中可觀察到，當施加一水平電場於BPIII，經電場誘發之複折射率隨電場強度增強而增加並且無遲滯現象。BPIII 在光學均向暗態與光學非均向亮態間的切換速度約6 毫秒。
本論文亦使用介電異方性大於零之液晶材料，並添加旋光性分子產生一螺距近似之藍相液晶。而比較兩樣品發現，當螺距近似時，藍相存在之溫度範圍並不相似。兩樣品之電光特性行為相似，但由於經電場誘發之慢軸方向互相垂直，造成旋光方向相反。

In this thesis, we used a liquid crystal with negative dielectric anisotropy and added chiral dopant with moderate helical twisting power (HTP) to produce BP. The temperature range of amorphous blue phase (BPIII) is about 8.5 ◦C and it covers room temperature.
From the experimental results, we observe that, as a horizontal electric field is applied on BPIII, the induced birefringence enhanced as the electric field increasing and hysterisis effect,is free. The response time of BPIII is short in dark state and bright state
switching.
We also used a liquid crystal with positive dielectric anisotropy and added chiral dopant to produce BP in similar pitch. Comparison with two samples, even if the pitch is similar, the temperature ranges of BP are not similar. The electro-optical characteristics of two samples are similar, but the optical rotations of light areoppositely because the induced slow axes are vertically.

誌謝. . . . . . . . . . . . . . . . . . . . . . . . . . i
摘要. . . . . . . . . . . . . . . . . . . . . . . . . .ii
Abstract . . . . . . . . . . . . . . . . . . . . . . .iii
Contents . . . . . . . . . . . . . . . . . . . . . . . iv
List of Figures . . . . . . . . . . . . . . . . . . . vii
List of Tables . . . . . . . . . . . . . . . . . . . .xiv
第一章緒論. . . . . . . . . . . . . . . . . . . . . . . .1
1.1 液晶(Liquid Crystal) . . . . . . . . . . . . . . . .1
1.2 藍相液晶(Blue Phase Liquid Crystal)[1] . . . . . . . 6
1.2.1 藍相液晶結構. . . . . . . . . . . . . . . . . . . .6
1.2.2 藍相液晶相態判定. . . . . . . . . . . . . . . . . 10
1.2.3 藍相溫寬拓寬. . . . . . . . . . . . . . . . . . . 14
1.3 藍相液晶的電光特性. . . . . . . . . . . . . . . . . 22
1.4 研究動機與目的. . . . . . . . . . . . . . . . . . . 25
第二章理論. . . . . . . . . . . . . . . . . . . . . . . 29
2.1 藍相液晶理論. . . . . . . . . . . . . . . . . . . . 29
2.1.1 晶格藍相缺陷理論(Defect Theory)[1] . . . . . . . 29
2.1.2 霧狀藍相成形理論[43] . . . . . . . . . . . . . . .31
2.1.3 藍相液晶之電場效應[1] . . . . . . . . . . . . . . 35
第三章實驗架構. . . . . . . . . . . . . . . . . . . . . 40
3.1 樣品配製. . . . . . . . . . . . . . . . . . . . . . 40
3.2 BPIII 之電光特性量測. . . . . . . . . . . . . . . . 45
3.2.1 光譜量測. . . . . . . . . . . . . . . . . . . . . 46
3.2.2 穿透/反射光強值量測. . . . . . . . . . . . . . . .47
3.2.3 反應時間量測. . . . . . . . . . . . . . . . . . . 48
3.3 偏振態量測. . . . . . . . . . . . . . . . . . . . . 49
3.4 利用相位對比(Phase Contract)[47] 顯微鏡觀察折射率變化 50
第四章實驗結果. . . . . . . . . . . . . . . . . . . . . 52
4.1 電光特性量測. . . . . . . . . . . . . . . . . . . . 55
4.1.1 光譜量測. . . . . . . . . . . . . . . . . . . . . 55
4.1.2 BPIIIn 樣品光強度隨外加電壓之變化、遲滯現象及反應時間量測. . . . . . . . . . . . . . . . . . . 60
4.1.3 偏振態. . . . . . . . . . . . . . . . . . . . . .76
4.2 比較使用正負型液晶材料所形成BPIII . . . . . . . . . .86
4.2.1 BPIII 光譜及溫寬量測. . . . . . . . . . . . . . . 86
4.2.2 電光特性量測. . . . . . . . . . . . . . . . . . . 89
4.2.3 偏振態比較. . . . . . . . . . . . . . . . . . . . 98
第五章結論. . . . . . . . . . . . . . . . . . . . . . .105
References. . . . . . . . . . . . . . . . . . . . . . 107

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