本論文主要研究偶氮苯液晶、向列型液晶及聚合物單體混合物之光電特性，並利用此混合物製作一以紫外光寫入且無需偏振片之液晶顯示元件。該元件可利用偶氮苯液晶的兩種同分異構物(trans-態及cis-態)之不同吸收頻譜，及聚合物單體(DPPA)之高黏滯係數性質，使樣品於散射態及穿透態間切換，達到利用不同波段的光進行圖樣寫入及抹除之效果。本論文提出方法相當簡單，且寫入及抹除圖樣之光源無須偏振態。在圖樣寫入方面，選擇trans-態吸收率高於cis-態之波長(365 nm)光源，而抹除圖樣則採用cis-態吸收率高於trans-態的波長(532 nm)光源。由實驗可知樣品寫入或抹除所需時間與照射光源強度有關，光源強度越強則所需時間越短。另外可利用固定強度之光源照射樣品不同時間，則可得到不同穿透程度，亦即達到顯示灰階效果。此外，所寫入之圖樣對比經實驗測量為105:1，且利用此方法寫入之圖樣具有穩態，論文中將有詳細的驗證及機制說明。有關圖樣抹除方面，除上述利用光抹除的方法外，由於所使用之材料於高溫環境下的相變，及偶氮苯液晶於cis-態加熱後會轉變為trans-態的性質，故亦可利用熱將所寫入之圖樣進行抹除，且圖樣經光或熱抹除後的液晶樣品亦可重複寫入新的圖樣。

This thesis reports the results obtained from the studies of electro-optical characteristics of the mixtures based on azobenzene liquid crystal, nematic liquid crystal and monomer. The mixtures are adopted to fabricate an optically addressable and polarizer-free liquid crystal display. Because of the different absorption spectra between the trans- and cis-isomer of azobenzene liquid crystal, and the high viscosity of the used DPPA monomers, this LC device can be switched between scattering and transparent modes using different-wavelength light. The approach to address and erase the pattern is very simple. In the part of addressing (erasing) patterns, UV (green) light is used as the light source since the absorbance of UV light by trans-isomer (cis-isomer) is higher than that by cis-isomer (trans-isomer). Experimentally, the required duration to address and erase a display is found to decrease with the increase of the used light source. Additionally, the display gray scale can be achieved by the variation of illumination duration of UV light. The maximum contrast ratio is measured to be around 105. It should be noted that the written patterns are permanent after the light source is blocked. Restated, this display device is multi-stable. Moreover, in addition to the optically erased patterns, the addressed patterns can be erased by thermal treatment as well. The optically or thermally treated sample is optically rewritable. The detailed experimental results will be demonstrated and discussed in the thesis.

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