劣化與還原液晶之光電及電學特性

Electro-Optical and Electrical Characteristics of a Hydrodegraded and Recovered Liquid Crystal

王俊才(Chun-Tsai Wang)

指導教授 ： 李偉

中原大學/理學院/物理研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100743

摘要

密閉容器中的市售液晶即便保存在防潮櫃裡，也會因為放置過久導致液晶材料劣化；劣化的液晶顯示出增高的導電率，其離子雜質含量的增加使它無法再用於元件之製作。本論文旨在探討液晶材料的自然老化現象，找出造成液晶材料劣化的主因，並利用乾燥劑來恢復液晶原有的電性。
實驗結果得到以下幾個結論：
一、經適當貯存之舊液晶的劣化，多肇因於空氣中水分子對液晶材料的汙染，造成材料中離子濃度增加。
二、以相同重量的乾燥劑吸附空氣中之水分子，結果顯示配位高分子M2B擁有最好的吸附能力。
三、添加相同重量百分濃度之不同乾燥劑到劣化液晶，藉由直流偏壓下光電與電性量測之觀察，皆可獲知M2B比分子篩MS3在還原液晶效果上來得好。
四、添加30 wt%之M2B到舊的液晶裡進行吸水，經過176小時候，其電壓保持率已與新的液晶相似。

關鍵字

乾燥劑 ； 光電特性 ； 電學特性 ； 液晶

並列摘要

Even though preserved in moisture-proof cabinet, commercial liquid crystals in airtight containers will degrade over time. The degraded liquid crystals exhibit increased conductivity, and the increased content of ion impurities disables their use in fabrication of devices. This thesis aims to discuss the natural aging phenomenon of liquid-crystal materials and to find out the main reason of their deterioration. In addition, the present thesis demonstrates the use of desiccating agents to restore the original electrical characteristics of liquid crystals.
The following conclusions can be reached in accordance with the experimental results:
1. Degradation of old liquid crystals in stock often originates from contamination of atmospheric water, causing increase in ion content in the material.
2. Based on the result of a comparative test involving several desiccants of initially identical weight to absorb atmospheric water, the coordination polymer M2B exhibits the highest water-absorption capacity.
3. Our data of dc electro-optical and electrical measurements show that M2B is superior to the molecular sieve MS3 in refreshing the stored liquid crystals.
4. The degraded liquid crystal resembles its fresh counterpart in terms of the voltage holding ratio after 176-h treatment with 30 wt% M2B.

並列關鍵字

electro-optical characteristics ； electrical characteristics ； liquid crystal ； desiccating agents

參考文獻

[33] 劉軒宏，《摻雜不同維度奈米粒子液晶之時變介電特性》，碩士論文，中原大學物理學系，民99年7月。

[1] N. Sasaki, “Simulation of the voltage holding ratio in liquid crystal displays with a constant charge model,” Japanese Journal of Applied Physics 37(11), 60656070 (1998).

[2] T. Nakanishi, T. Takahashi, H. Mada, and S. Sato, “Transient behavior of voltage holding ratio in nematic liquid crystal cells,” Japanese Journal of Applied Physics 41(6A), 37523757 (2002).

[3] M. Mizusaki, T. Miyashita, T. Uchida, Y. Yamada, Y. Ishii, and S. Mizushima, “Generation mechanism of residual direct current voltage in a liquid crystal display and its evaluation parameters related to liquid crystal and alignment layer materials,” Journal of Applied Physics 102(1), 014904¬16 (2007).

[4] W. Lee, C.-Y. Wang, and Y.-C. Shih, “Effects of carbon nanosolids on the electro-optical properties of a twisted nematic liquid-crystal host,” Applied Physics Letters 85(4), 513–515 (2004).