高分子穩定負型液晶之暫態充電電流

Transient Charging Current in Polymer-Stabilized Liquid Crystals with Negative Dielectric Anisotropy

張新溢(Hsin-Yi Chang)

指導教授 ： 李偉

中原大學/理學院/應用物理研究所/碩士(2008年)

https://doi.org/10.6840/cycu200900191

摘要

中文摘要
本論文主要探討在不同聚合條件（高分子單體濃度、紫外光強度、聚合時間和聚合電壓）所形成的高分子穩定負型液晶（MLC-6884）中，由直流階梯型電壓開啟瞬間所誘發之暫態電流的行為。藉由暫態電流的量測數據，可瞭解液晶分子所產生的轉向動態以及在液晶與配向層界面上因離子堆積所形成的場遮蔽現象，並進一步討論峰值電流、峰值時間及電位移電荷密度三者的結果。
我們可以將實驗結果分成三個部份來說明：第一，隨著高分子單體濃度、聚合光強度或聚合時間之增加，暫態的峰值和電位移電荷密度之值變小，但峰值時間卻隨之增加；第二、高分子單體濃度或聚合光強度的增加，都會使液晶盒內產生較嚴重的離子場遮蔽效應，造成峰值電流較弱與峰值時間較慢；第三、有外加交流聚合電壓的情況之下，液晶分子的預傾角略為下降，致使液晶分子更易發生轉動，故可獲得較快的峰值時間。

關鍵字

高分子穩定負型液晶 ； 暫態充電電流

並列摘要

Abstract
In this study transient current measurement technique has been used to investigate the orientational dynamics of MLC-6884 liquid-crystal molecules with negative dielectric anisotropy and the field-screening phenomenon cause by accumulated ions at the interfaces between the alignment and liquid-crystal layers in a polymer-stabilized liquid-crystal cell under external field. The polymer-stabilized liquid crystals have been prepared with different external conditions, viz. the concentration of the monomer, the intensity of the ultraviolet light, the curing time and the curing voltage. The peak current, peak time and the displacement charge density have been obtained from fitting the experimental data with mathematical equations.
There are three conclusive results derived from the experiment. First, as the concentration of the monomer, the intensity of the ultraviolet light or the curing time increases, both the peak current and displacement charge density decrease and the peak time becomes longer. Second, increase in the concentration of the monomer or the intensity of the ultraviolet light causes the liquid-crystal cell to exhibit the serious field screening, which results in the weaker peak current and slower peak time. Third, with the curing ac voltage, the pretilt angle reduces, making the reorientation of the nematic to take place more easily and permitting a shorter peak time.

並列關鍵字

Polymer-Stabilized Liquid Crystals with Negative Dielec ； Transient Charging Current

參考文獻

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