| 研究生: |
石博仁 Shih, Po-Jen |
|---|---|
| 論文名稱: |
膽固醇液晶平面及焦錐結構直接切換之研究 Direct switching between planar and focal conic textures in cholesteric liquid crystals |
| 指導教授: |
傅永貴
Fuh, Ying-Guey Andy |
| 學位類別: |
碩士 Master |
| 系所名稱: |
理學院 - 物理學系 Department of Physics |
| 論文出版年: | 2011 |
| 畢業學年度: | 99 |
| 語文別: | 中文 |
| 論文頁數: | 110 |
| 中文關鍵詞: | 膽固醇液晶 、液晶 、偶氮染料 、平面結構 、焦錐結構 |
| 外文關鍵詞: | cholesteric liquid crystals, liquid crystals, azo dye, planar, focol conic |
| 相關次數: | 點閱:107 下載:7 |
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本論文探討有關照光及溫度調控直接切換膽固醇液晶平面結構與焦錐結構,機制上主要利用照光激發偶氮染料引致光致熱效應,使膽固醇液晶升溫並相變至各向同性態,當關閉照射光後使液晶自然降溫而形成散射的焦錐結構(focal conic texture),故可由反射的平面結構(planar texture)轉換至散射的焦錐結構,並可利用降溫使所使用之膽固醇液晶螺距變長而提高焦錐結構的自由能,使能量越過平面結構及焦錐結構之間的位能障壁,而由焦錐結構轉回平面結構,此方法即膽固醇液晶兩種結構的直接切換的結果。實驗分兩個部分,第一部分利用甲基橙(MO)摻雜在PVA使用溶劑DMSO製成薄膜材料並旋轉塗佈在ITO玻離基板上,以其所製作的液晶盒進行實驗,實驗結果發現光致熱效應使膽固醇液晶達到各向同性的相變溫度所需的光強度相當高,為了克服此缺點,於第二部分的實驗,我們利用另一種偶氮染料(DR1)直接摻雜在膽固醇液晶注入液晶盒,同樣利用光致熱效應重複第一部分實驗,結果發現所需要的線偏振光強度僅前者十分之一左右且同樣經過降溫過程可使平面結構轉換至焦錐結構,另可利用改變溫度使膽固醇液晶螺距增長而使焦錐結構轉回平面結構,此法也達到膽固醇液晶兩種結構的直接切換效果。最後我們利用該實驗結果製作出一個雙穩態液晶顯示元件。
This thesis investigates the direct switching between planar and focal conic textures in cholesteric liquid crystals (CLCs) by light illumination and cooling treatment. The planar CLCs are heated to isotropic state by light-induced thermal effect resulted from the absorbed light by azo dyes, and then, changed to the focal conic texture after blocking the light and naturally being cooled to room temperature. Additionally, the pitch length of the used CLCs herein can be elongated as decreasing the temperature, which results in the instability of focal conic texture. Hence, the focal conic textures are transferred to planar textures by cooling the LC sample.Experiments can be summaried into two parts. The first part of the experiment demonstrates the direct switching of these two textures of CLCs in a LC sample fabricated by two ITO glass substrates. One of these two substrates was coated with a methyl orange-doped PVA film. Experimental results show that the required light intensity and switching time from planar to focal conic textures are extremely high and long. In order to overcome this shortage, we repeat the above experiment using the azo dye-doped CLCs rather than azo dye-doped PVA films in the second part of the experiments.The results show that the required light intensity decreases to one tenth of the previous experiment, and the switching time decreases to about ten seconds. Finally, a bistable optical addressing, cooling/voltage erasing and optical re-addressing liquid crystal display is demonstrated.
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