臺灣博碩士論文加值系統

　　聚合物穩定膽固醇液晶結構薄膜(Polymer-stabilized Cholesteric Texture簡稱PSCT)是近年來最廣為探討的液晶元件之一。其主要是以聚合物枝條來穩定膽固醇液晶之結構，當外加電場時膽固醇液晶的結構會隨著變化，進而可達成顯示之目的。

　　在本論文中，我們為達PSCT光電特性之最佳化，嘗試了多種不同中間基長度之monomer，並找出最合適之monomer種類及濃度比率。也將SmC* 液晶加入材料中，觀察其對PSCT光電特性之影響。結果顯示加入SmC*會使polymer network分布變得更均勻密集，故使PSCT之Vth降低、 變大。

　　另外，我們以表面配向材料取代polymer來穩定膽固醇液晶之結構，並成功地製成SSCT元件(Surface-stabilized Cholesteric Texture)。

　　最後，我們發現PSCT cell之繞射形成似Qu’etelet環圖案，並量測繞射形成中其強度之動態變化。我們證實了繞射訊號是經由cell中之「focal conic domain液晶」及「polymer network枝條」對Ar+雷射之散射所造成。故此繞射強度之變化隱含了PSCT cell之polymer network枝條的生長狀態及cholesteric液晶於cell之texture狀態的訊息。此外，量測第一階光強與外加電壓之關係發現與其光電特性相關，所以此繞射強度變化之量測提供了一種對PSCT元件之非破壞性解析方式。

　　Polymer-stabilized Cholesteric Textures (PSCT) have been extensively studied in recent years. Primarily, the formed polymer networks can stabilize the textures of cholesteric LC domains. The fabricated PSCT film can be controlled with the application of a voltage to achieve various transmittance states, thus is potential for use as a display.

　　To optimize the electro-optic characteristics of a PSCT device, we use some monomers with various lengths of rigid core. The most optimum one and the concentration ratio of monomer to LC is deduced in this thesis. We also study the effect of the doping of SmC* in a PSCT sample. The results show that the distribution of the polymer networks become more uniform after doping of SmC*. Thus, the threshold voltage, Vth, reduces and the hysteresis width, DV, rises in the PSCT device.

　　Also, we have successfully fabricated the Surface-Stabilized Cholesteric Texture (SSCT) devices. The role of the polymer network is replaced by the surface alignment treatment.

　　Finally, we have performed the diffraction from the PSCT films, forming the Qu’etele-type ring pattern. We measure the dynamic change of the first-order diffraction intensities during polymerization of a sample. After polymerization, both the electro-optical characteristics and the diffracted intensities of various orders are measured. We conclude that the diffraction is attributable to the scattering of the light from the “focal conic domains of cholesteric LC” and the “the clusters of the polymer networks” in the PSCT cells. The variation of the first-order diffraction intensities as a function of the applied voltage is found to correlate with that of the electro-optical characteristics of PSCT cells. Thus, the diffraction measurements could provide us with another qualitative, nondestructive method to analyze PSCT devices.

中文摘要………………………………………………………………i
英文摘要………………………………………………………………iii
誌　謝…………………………………………………………………v
目　錄…………………………………………………………………vi
圖表索引………………………………………………………………viii

第一章　論文研究方向與目的………………………………………1

第二章　簡　介
　§2-1 液晶簡介
　　§2-1-1 前言…………………………………………………………2
　　§2-1-2 秩序參數S …………………………………………………3
　　§2-1-3 液晶的分類…………………………………………………4
　　§2-1-4 液晶之非均向性 (Anisotropic) ……………………………11
　　§2-1-5 電場對絕緣Nematic液晶的影響…………………………17
　§2-2 PSCT (Polymer-stabilized Cholesteric Textures)元件簡介
　　§2-2-1 Cholesteric 液晶之結構…………………………………19
　　§2-2-2 PSCT元件分類……………………………………………21

第三章　實驗準備
　§3-1 PSCT normal mode樣品製作
　　§3-1-1 材料特性介紹……………………………………………26
　　§3-1-2 PSCT元件製作……………………………………………29
　　§3-1-3 SEM樣品備製………………………………………………30
　§3-2 儀器Setup及量測方式…………………………………………31

第四章　實驗結果與分析
　§4-1 不同中間基長度之monomer對PSCT光電特性影響之研究
　　§4-1-1 實驗內容……………………………………………………34
　　§4-1-2 實驗結果與分析……………………………………………35
　　§4-1-3 實驗結論……………………………………………………36
　§4-2 SmC* doped 對PSCT光電特性影響之研究
　　§4-2-1 實驗內容……………………………………………………42
　　§4-2-2 實驗結果與分析……………………………………………43
　§4-3 Surface-Stabilized Cholesteric Texture 之研究
　　§4-3-1 前言…………………………………………………………48
　　§4-3-2 實驗方法與材料……………………………………………48
　　§4-3-3 結果與討論…………………………………………………50
　§4-4 PSCT之新型驅動方式可行性探討
　　§4-4-1 前言…………………………………………………………58
　　§4-4-2 實驗準備……………………………………………………59
　　§4-4-3 實驗結果與分析……………………………………………60
　§4-5 PSCT cell之繞射[一種real time、非破壞性之監測方式]
　　§4-5-1 前言…………………………………………………………64
　　§4-5-2 Qu’etelet-type繞射理論 ……………………………………65
　　§4-5-3 實驗結果與分析……………………………………………68
　　§4-5-4 結論…………………………………………………………75

第五章　總結與展望………………………………………………………76

參考文獻………………………………………………………………………A-1

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