近年來非接觸式液晶表面配向技術一直是產業及學術界研究的重要課題，從許多文獻中可得知，物質在奈米尺度下由於凡德瓦爾力(Van der Waals forces)等較弱分子力效應及較大之表面與體積比值 ，其材料表現出的物化性質會與塊材有所不同。繼2005年Sharp公司利用奈米粒子的摻雜改變液晶分子配向後，後續也發現摻雜適量奈米粒子-Polyhedral Oligomeric Silsesquioxanes (POSS)可使液晶分子垂直配向基板表面的方法，此項結果可減少面板製程上繁複的步驟、時間並降低成本。比起傳統垂直配向膜，摻雜POSS於液晶材料中用以配向可省去高溫烘烤等許多的步驟，更適合應用在近年來蓬勃發展的塑膠基板製程上。為了增加POSS提供垂直於基板表面配向的空間可變性，本論文主要探討奈米粒子(POSS)與高分子聚合物(NOA81)之吸附特性，進而將POSS摻雜入NOA81並，利用聚合反應產生之配向薄膜，製作出可自由變換的垂直配向圖樣。
本研究架構主要分為兩部分，第一部分是探討奈米粒子-POSS在高分子-NOA81薄膜上之吸附能力，以及在PVA水平配向薄膜上，塗佈摻雜POSS之NOA81高分子聚合物薄膜，並利用光蝕刻決定聚合區域，最終於照光區摻雜POSS之高分子聚合物會引致液晶垂直排列，再藉由適當溶劑洗掉非照光區之未聚合高分子，使得基板露出表層PVA水平配向膜而使液晶分子產生水平配向，最後達到同一液晶盒有兩種以上配向之結構。第二部分是利用上述具有垂直配向能力之POSS-NOA81高分子聚合薄膜製作以下幾種液晶元件，分別介紹如下：
(1) 相位光柵
利用塗佈POSS-NOA81高分子聚合薄膜製作垂直與混成(水平+垂直)配向之線條型光柵，其兩相同區域之間隔距離為 50 μm，由垂直與混成(hybrid)配向組成之二元配向結構光柵。並藉由不同外加電壓可控制其一階繞射強度大小，實驗結果顯示，當入射光偏振方向平行hybrid水平配向面之液晶導軸時，其繞射效率最高可達到26.5%。藉由外加電壓值改變可完全將其繞射效果關閉。
(2) 依視角決定之顯示器
此原件是利用與相位光柵製作的同一方法，將垂直與混成配向組成之二元線條型光柵，但週期更改為1mm，並搭配前後互相垂直的偏振片製作出依視角切換顯示圖片之顯示器。實驗結果顯示，改變視角所得之亮暗態與1D-DIMOS模擬之結果相當符合，可達到不同視角觀看不同圖片之成果。
(3) 半反半穿液晶顯示器
該部分應用是利用前述之POSS-NOA81聚合薄膜可達到不同區域不同配向之結果，製作出由水平與混成的二元配向液晶元件。預期在特定外加電壓下可得到水平配向區域與混成配向區域相位延遲為2:1，再配合偏振片、四分之一波板與反射鏡之設計，可達成在相同外加電壓下反射區與穿透區亮度相同之結果。從實驗結果分析得到其水平與混成配向兩區域相位延遲接近2:1，在外加電壓為6 V時為亮態，待電壓加到14V呈現極佳的暗態，如此即可應用在單一液晶盒厚度之半反半穿液晶顯示器。

Recently, no-contact methods for aligning liquid crystals (LCs) have been extensively studied in industrial and academic communities. According to many scientific literatures, the physical and chemical properties of nano-sized particles are very different from their bulk materials owning to their weak Van der Waals forces, large surface to volume ratio, etc. Since Sharp Co. Ltd proposed a homeotropically aligned LC cell by adding nano-particles in negative dielectric LCs to without the use of an alignment layer in 2005, there has been many groups world-wide carrying out R&Ds in this area. One of the novel Nanoparticles, named Polyhedral Oligomeric Silsesquioxanes (POSS), has been developed to align LCs homeotropically as well. The technique of using nanoparticles-doped LCs to achieve LC alignment without coating alignment layers, such as DMOAP can simplify the fabrication process, and thus, reduce the manufacture cost. Notably, such a technique is especially suitable for fabricating flexible LC devices because of the low-temperature process.
This thesis studies the alignment characteristics of POSS-doped polymer films, and demonstrates a novel approach to achieve patterned homeotropic LC alignment using such films.
Briefly, the thesis consists of two parts. The first part is the LC alignment by a POSS-doped polymer film coated onto a homogeneous alignment layer (PVA)-coated glass substrate. The other is the application using this method to fabricate various devices including phase grating, viewing-angle-dependent LCD and transflective LCD. These three devices are summarized as follows:
1. Phase grating:
A LC grating with binary LC alignments, defined as two different common LC alignments in a single pixel or a specific area, are fabricated using a stripe-type photomask with alternating opaque and transparent stripes having a spacing of 50 μm. In this work, a LC phase grating composed of vertical and hybrid (vertical + homogeneous) alignments was made. The results show that the first-order diffraction efficiency of the grating is electrically switchable, and the maximum diffraction efficiency of the first-order diffraction signal can reach ~26.5%.
2. Viewing-angle dependent LCD:
In this part, a binary LC alignment as described in part 1, except for the spacing is used to fabricate viewing-angle-dependent LCDs. It is achieved by sandwiching a binary-alignment LC cell between two crossed polarizers. The experimental results were found to agree well with those obtained using 1D-DIMOS simulation.
3. Transflective LCD:
Using the results of the binary LC alignments, a transflective LCD with a single cell gap was demonstrated. The LCs in the transmissive and reflective pixels were homogeneous and hybrid alignment, respectively. When an AC voltage (6 V) is applied, a bright state is achieved. The phase retardation ratio of the transmissive and reflective regions is 1:2. Grayscale can be obtained by increasing the applied voltage from 6 V to 14 V.

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