摻高分子穩定強誘電性液晶盒配向均勻性與光電特性之研究

A Study of the Alignment Uniformity and Electro-optic Characteristics of a Polymer-Stabilized Ferroelectric Liquid Crystal Cell

姚志達(Chih-Da Yao)

指導教授 ： 吳俊傑 ； 陳殿榮

國立臺北科技大學/電資學院/光電工程系研究所/碩士(2010年)

摘要

本研究將可光聚合單體摻入水平配向強誘電性液晶盒中，利用在SmC*相照射UV光方式。探討單體/液晶重量百分比濃度對於配向均勻性與光電特性的影響。
由實驗結果得知，同向平行配向液晶盒在未照射UV光前，液晶盒即可具有整體為單一區塊的配向，其T-V曲線為非對稱的V shaped。在完成UV照光後，配向仍維持均勻，但由於液晶分子傾角提高的關係，使得液晶分子偏離rubbing方向，其T-V曲線會由非對稱的V轉變成Half-V shaped曲線。另外，反向平行配向液晶盒在未照射UV光前，液晶盒也具有單一區塊配向，在完成照光後，配向也仍維持均勻，但由於液晶分子傾角提高的關係，造成液晶分子兩邊的cone angle減少，其T-V曲線隨著光聚合單體濃度上升而下降。
整體上，我們利用高分子網穩定強誘電性液晶分子的排列，可達到均勻配向的效果。兩者皆具有灰階顯示能力並呈現單穩態操作模式。除此之外，當我們將液晶盒升溫至SmA又降溫至結晶相再回到室溫時，配向均勻性以及光電特性仍不改變，代表其具有良好的溫度穩定性。而此PSFLC也能提升顯示器的對比達到380：1。

關鍵字

高分子穩定強誘電性液晶 ； 缺陷改善 ； 傾角 ； 穩定度

並列摘要

We develop the polymer-stabilized ferroelectric liquid crystal (PSFLC) cell, in which the photo-curable monomer is doped in FLC and photocured in the SmC* phase. In this study, we investigate the effect of monomer/FLC mixture concentration on the molecular alignment and electro-optical properties of the PSFLC cell.
Experimental results show that the mono-domain alignment can be achieved in a PSFLC cell before the photo-curing process. The T-V curve of this cell shows an asymmetric V shape switching. After photo-curing in the SmC* phase, the alignment of the cell keeps uniform. In the case of cell with parallel rubbing, the T-V curve is changed from asymmetric V to half-V shape switching due to the increase of the surface pretilt angle. On the other hand, for an anti-parallel rubbed cell the increase of surface pretilt angle leads to the reduction of the effective cone angle; therefore, the T-V curve of the cell still shows asymmetric V shape switching but the maximum transmittance decreases as the mixture concentration increases.
As a result, our parallel and anti-parallel PSFLC cells exhibit mono-domain alignment and grayscale capability in electro-optical performance. In addition, these proposed PSFLC cells have good thermal stability; The alignment and electro-optical property do not change even the cell is cooled to -15 and heated to 70, which is lower and higher than the SmC*-crystal and SmC*-SmA phase transition temperature, respectively. In particular, the PSFLC cell can show a defect-free and very good dark state. The contrast ratio reaches to 380.

並列關鍵字

PS-FLC ； Zigzag-free ； Tilt angle ； Thermal stability

參考文獻

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