摻雜奈米粒子之鐵電型液晶元件的離子效應與光電特性研究

Effect of Nanoparticles Addition on Ion Current and Electro-optical Characteristic in Surface Stabilized Ferroelectric Liquid Crystal Cells

劉詠薇(Yung-Wei Liu)

指導教授 ： 趙治宇

國立臺灣大學/理學院/物理研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.10113

摘要

液晶顯示器中含有大量離子，這些由液晶材料及製程中所產生的離子在外加電場下會造成反向電壓，形成屏蔽效應使得有效電壓降低。這樣的離子效應一直是影響液晶顯示器顯示品質的主要因素。鐵電型液晶材料在液晶材料學中是相當有潛力的材料，有著快速反應的優點，但也有離子效應過大的缺點，因此如何有效降低離子效應是鐵電型液晶在未來顯示器應用上相當重要的課題。
本研究主要目的在觀察並比較摻雜奈米粒子於鐵電型液晶元件對離子電流與光電特性所造成之影響。在本論文中，我們製作了摻雜鑽石、二氧化鈦以及二氧化矽等奈米粉末的表面安定型鐵電液晶(SSFLC)晶胞。我們以偏光顯微鏡觀察液晶晶胞表面配向效果，並進行光穿透率及離子電流的實驗架設與量測。實驗結果顯示摻雜奈米粉末對於表面安定型鐵電液晶晶胞表面的配向以及光電特性並不造成顯著的影響，但能有效降低離子電流，其離子濃度可降低至未添加奈米粒子液晶晶胞的三十分之一。這樣的結果提供未來顯示器技術在降低離子效應的新方向，可藉由在鐵電型液晶中添加奈米粒子來降低離子效應同時不改變顯示器的光電表現。

關鍵字

液晶 ； 鐵電型 ； 液晶顯示器 ； 離子效應 ； 奈米粒子

並列摘要

Liquid crystal displays (LCDs) usually contain many ions that come from either the raw material itself or from impurities during cell fabrication. These ions are dissociated by applying voltage to form an inverse electric field inside the cell and cause lots ion effects such as flickers, image sticking, etc. Such ion effects are the main cause to influence the LCD quality. Among the liquid crystal material science, ferroelectric liquid crystal (FLC) is a material with great potentiality for the high switching speed, but also have drawback for large ion concentration. Therefore, how to effectively reduce the ion concentration is an crucial issue on FLC for application of display technology in the future.
The purpose of this study is to observe and compare the effect of nanoparticles addition on ion current and electro-optical characteristic in surface-stabilized ferroelectric liquid crystal (SSFLC). We prepare SSFLC cells doped with three kinds of nanoparticles such as diamond powder, TiO2 and SiO2. Experimentally, we use polarizing microscope to observe the surface alignment of the samples; set up and proceed the transmittance and transient current measurements.
Experimental results show that nanoparticles addition in SSFLC cell do not significantly influence its electric-optical performance. However, the ion currents of doped SSFLC cells are enormously decreased as the doping concentration increase. And the ion concentration can be lowered to 1/30 of pure SSFLC cells. Such results reveal that the ion effects of FLCD can be weakened by simply adding nanoparticles into it without influence its electric-optical performance. This may have a great contribution on the application of display technology in the future.

並列關鍵字

liquid crystal ； ferroelectric ； LCD ； ion effect ； nanoparticles

參考文獻

[17] Hsueh-Ying Huang, Master Thesis, National Central University (2003).

References of Chapter 1

[2] H. Naito, K. Yoshida, and M. Okuda, “Transient charging current in nematic liquid crystals”. JAP 73, 1119 (1993).

[3] S. Vermael, G. Stojmenovik, K. Neyts, D. de Boer, F. Anibal Fernandez, S. E. Day, and R. W. James, “3-Dimensional ion transport in liquid crystals”. Jpn. J. Appl. Phys. Part 1 43, 4281 (2004).

[4] C. Colpaert, B. Maximus, and A. De Meyere, “Adequate measuring techniques for ions in liquid crystals”. Liquid Crystals 21, 133 (1996).