向列型液晶摻雜高分子材料之光電特性及其應用;Electro-optical characteristics of polymer-doped nematic liquid crystals and their applications

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/83519

Title:	向列型液晶摻雜高分子材料之光電特性及其應用;Electro-optical characteristics of polymer-doped nematic liquid crystals and their applications
Authors:	李中宇;Li, Chung-Yu
Contributors:	光電科學與工程學系
Keywords:	偶氮染料;吸附;特殊結構;威廉斯區塊;液晶
Date:	2020-08-20
Issue Date:	2020-09-02 15:45:40 (UTC+8)
Publisher:	國立中央大學
Abstract:	液晶一直是發展諸多類型光電元件的熱門材料之一，不論是最常見的顯示器與智慧窗戶，亦或是生活中各類數位、電子與多媒體產品，液晶光電科技已成為人們日常生活中不可或缺的技術，如今不可再生能源的衰竭引導科技走向節能與永續發展，故穩態液晶元件及半反半穿式液晶顯示相關元件的研究為現在重要發展方向之一。本論文主要分為兩部分討論，第一部分為聚合物網絡液晶(polymer-network liquid crystal, 簡稱為PNLC)之偏振選擇性散射研究，利用液晶聚合物(RM257)混合向列型液晶(E7)經照射UV光固化形成聚合物網絡結構之特性，在施加電場下使液晶分子因改變排列方向而使液晶與液晶聚合物因折射率不匹配導致液晶盒為散射態，由不同偏振方向之線偏振光入射不同PNLC液晶盒會有不同之散射程度，其具有偏振選擇性散射可藉由電控形成高對比之穿透與散射態；另以相同光強度不同線偏振方向之UV光固化液晶聚合物，比較不同液晶盒之閥值電壓、電壓遲滯寬度及聚合物固化完整度等。第二部分為摻雜偶氮染料與聚合物於向列型液晶之光電特性研究，以負型向列型液晶(HNG30400-200)摻雜偶氮染料(Methyl Red, 簡稱為MR)與兩種聚合物(NOA68TH及、RM257)製成之液晶盒，在施加電場形成威廉斯區塊之線條結構下照光進行MR吸附之光配向製程，亦即染料受綠光激發而吸附於基板上，在關閉施加電場後因賓主效應使液晶排列成特殊結構，在偏振片穿透軸相互正交之偏光顯微鏡下可觀察到類似於威廉斯區塊的亮暗線條結構。 ;In recent decades, liquid crystal (LC) is one of the famous materials for the applications of many types of electronics, such as LC displays, LC smart windows, and others. Therefore, LC technology is an indispensable technology in human’s daily life. Nowadays, non-renewable energy comes from sources, such as oil and coal, that will eventually run out, so the development of technologies moves towards energy conservation and sustainable development. In LC fields, it is definitely true that the development of bistable and multi-stable devices, as well as the transflective LC display devices, is an important key direction now. The thesis includes two parts, the first part is the study of polarization-selective light scattering by polymer-network liquid crystals (PNLC). The famous LC polymer, RM257, cured by UV light, is adopted to form the PNLC structures. The mismatch of the refractive indexes of LCs and polymers in a PNLC cell applied with suitable electric fields results in light scattering. Regarding the scattering of the incident light, one component of the incident light will be scattered by the PNLC cell, while the other component will smoothly penetrate the PNLC cell. Such a phenomenon is called polarization-selective light scattering. Moreover, using various UV light having different polarization directions to polymerize the polymers will obtain the PNLC cells having different threshold voltages, voltage hysteresis widths, and the uniformity and completion of polymerization. The second part of this thesis is the study of electro-optic characteristics of the azo dye (MR)- and polymer-doped nematic LCs. Experimentally, the doped MR molecules illuminated by green light will be adsorbed onto the substrate facing the incident light. Here, Williams domains can be initiated by applying a suitable voltage, and the doped MR molecules are simultaneously illuminated with green light to generate the specific structures of MR adsorption. Thereafter, the observation of the generated structures of LCs, resulting from the adsorbed MR, under a polarized optical microscope is similar to that of Williams domain. It indicates that the dynamic structures cannot be stabilized by the adsorbed MR, but the bright and dark stripes, resulting from the orientation of LCs based on the guest-host effect, can be recorded onto the LC cell.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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