藍相液晶是溫度區間存在於膽固醇相和各向同性相之間的中間相，由於其自聚集成週期性結構特性，因此擁有布拉格反射(Bragg reflection)，可視為三維光子晶體。藍相依結構及存在溫度區間又分為藍相一和藍相二，分別是體心立方晶格和簡單晶格。由於藍相一和藍相二週期性結構的差異，因此這兩者之間的布拉格反射波長也會跟著不同，所以利用光場切換藍相反射顏色是本篇論文的研究目標。
本實驗在藍相液晶中摻雜偶氮染料，其特性是用不同波長光激發使偶氮染料產生trans-cis同素異構化反應，此反應可改變藍相液晶的相變點，使藍相在同樣的溫度底下出現不同種相態，因為結構的改變使得反射波長也會跟著有所不同。
實驗中先在樣品後面塗黑當作背景，作為激發光源的紫光雷射其波長為404nm，可以使偶氮染料從trans態激發到cis態，並降低液晶之相變點，使樣品在固定溫度激發下，由膽固醇相變成藍相最後到達各向同性相。接著利用綠光雷射，其波長為532nm，可以使偶氮染料從cis回復到trans態，激發各向同性相引致成藍相最後回到一開始的膽固醇相，而完成一個循環。由於各個相態具有不同晶格結構及布拉格反射，我們可以在這循環中任意切換想要的反射顏色當成顯示器亮態，同時也可以把搭配黑色背景的各向同性相當作顯示器暗態，達到擁有亮暗態光控全彩多穩態反射式藍相顯示器。

Blue phase(BP) is a mesophase existed at temperature range between cholesteric phase and isotropic phase. BP can be classified into BP I and BP II according to their crystal structures. BP I is body-center cubic(BCC) and BP II is simple cubic(SC). Since BP is a self-assembled 3D photonic crystal, it has periodic structure and Bragg reflection properties. Due to the different structures of BP I and BP II, it provide with various photonic bandgap and wavelength of Bragg reflection. In this thesis, our purpose is to control the reflection wavelength of azo-dye doped BP using photo-addressing to achieve color reflective display.

First, we doped azo-dye to the blue phase liquid crystal. The trans-cis photoisomeration of azo-dye could be induced by irradiated 404nm laser. It can change the phase transition temperature of BPLC. The cholesteric phase would be changed to BP and then to isotropic phase at the same temperature under suitable excitation. Then irradiation of 532nm laser can induce back photoisomeration which can induce isotropic phase back into BP then to cholesteric phase. So we could obtain the desired reflection colors through the photoisomeration cycle. There are three colors(red, green, blue) in our BP as bright state. The isotropic phase with black background can be used as dark state. This study achieves a Light-driven, multistable and full-color reflective blue phase liquid crystal display.

中文審定書 i
英文審定書 ii
誌謝 iii
中文摘要 v
Abstract vi
目錄 vii
圖目錄 xiii
表目錄 xvi
緒論 xvii
第一章 液晶介紹 1
1-1何謂液晶 1
1-2液晶的種類 2
1-2-1棒狀熱致型液晶 3
1-3液晶的物理特性 6
1-3-1雙折射性 7
1-3-2溫度對液晶的影響 8
1-3-3介電常數的異向性 9
1-3-4液晶彈性連續理論 10
1-3-5 Freedericksz transition 11
第二章 藍相液晶介紹 12
2-1藍相液晶的發現 12
2-2藍相液晶的結構 13
2-3藍相液晶的光學特性 15
2-4藍相液晶的判斷方法 15
2-5聚合物穩固藍相液晶 18
2-6藍相液晶的電場效應(Electric field effect) 19
2-7克爾效應(Kerr effect) 20
2-8藍相液晶在光場下的行為 21
第三章 理論 22
3-1光引致分子結構改變效應 22
3-1-1正力矩效應-Jánossy model 22
3-1-2負力矩效應- Gibbons model 24
3-2光引致同素異構化反應 25
3-3光致熱效應 25
第四章 實驗方法與過程 26
4-1材料介紹 26
4-1-1向列型液晶 26
4-1-2旋性物質-High HTP 26
4-1-3偶氮染料 4-methoxyazobenzene(4MAB) 27
4-2設備介紹 28
4-3樣品製作 28
4-3-1藥品調配 28
4-3-2玻璃基板表面處理 29
4-3-3液晶盒製作 30
4-3-4液晶盒間距(cell gap)量測 31
4-3-5藥品注入液晶盒 32
4-4藍相反射光譜測量方法 33
4-5光激發藍相相變點調控系統架設 33
4-5-1觀察升降溫藍相相態改變 34
4-5-2觀察光激發藍相相態改變 35
第五章 結果與討論 36
5-1主體液晶比例對藍相液晶的影響 36
5-2旋性物質對藍相液晶的影響 37
5-2-1旋性物質對藍相液晶布拉格反射波長的影響 37
5-2-2旋性物質對藍相液晶相變點和溫寬的影響 38
5-3偶氮染料對藍相液晶的影響 38
5-3-1偶氮染料對藍相液晶布拉格反射的影響 38
5-3-2偶氮染料對藍相液晶相變點的影響 39
5-3-3偶氮染料對藍相液晶調控溫度的影響 40
5-4光激發藍相相變點調控 41
5-5光激發藍相布拉格反射波長之的調控 44
5-6對比度 48
5-7穩定度 49
5-8光寫入顯示 54
第六章 結論 55
參考文獻 56

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