摻雜碳奈米管之對掌性垂直排列型與扭轉向列型液晶盒的動態電光響應研究

Dynamic Electro-optical Responses of Chiral-homeotropic and Twist Nematic Liquid Crystal Cells Doped with Carbon Nanotube

張瑋儒(Wei-Ju Chang)

指導教授 ： 徐芝珊

中原大學/理學院/應用物理研究所/碩士(2007年)

https://doi.org/10.6840/CYCU.2007.00660

摘要

摘要
本論文探討垂直排列型液晶盒與扭轉向列型液晶盒，在摻雜碳奈米管於液晶樣品後，對液晶迴流振幅所造成的影響。由實驗結果得知，垂直排列型液晶盒樣品在摻雜碳奈米管後，可以看出較純液晶樣品有些微降低液晶的迴流振幅；在90a或{90a的對掌性垂直排列型液晶盒中，使用垂直配向劑DMOAP在摻雜碳奈米管後，明顯看出閾值電壓增加，且在低電壓時就可降低液晶的迴流振幅。若對掌性垂直排列型液晶盒樣品改用SE-1211為配向劑時，摻雜碳奈米管後閾值電壓幾乎沒改變，而在高電壓時液晶的迴流幅度會變小。
扭轉向列型液晶盒樣品在摻雜碳奈米管後，若施加電壓頻率為1 kHz時，低電壓不易看出摻雜碳奈米管是否有影響迴流振幅，而在高電壓時可些微看出，迴流幅度會因摻雜碳奈米管濃度增加而減小；若施加電壓頻率改為10 Hz，可明顯看出在高電壓時，摻雜碳奈米管的液晶樣品其迴流振幅比純液晶樣品小。

關鍵字

碳奈米管 ； 對掌性垂直排列型 ； 液晶 ； 扭轉向列型 ； 迴流

並列摘要

Abstract
We investigated the backflow effect in vertical-aligned (VA) and twisted nematic (TN) cells with pristine and carbon nanotube (CNT) -doped liquid crystal (LC) material. Experimental results show that doping with a small quantity of CNTs can suppress the backflow effect in VA mode. The magnitude of optical bounce becomes smaller with low applied voltages, and the threshold voltage is increasing in CNT-doped 90a and {90anchiral-homeotropic cells in which the vertical alignment layer is DMOAP. If we used polyimide SE-1211 for vertical alignment layer, the threshold voltage is not changed, and the optical bounce does not become smaller until high applied voltages.
When the low voltage with a frequency of 1 kHz is applied to the CNT-doped TNLC cells, the relationship between the magnitude of optical bounce and concentration of CNTs, is not clear. However, with the higher driving voltage, the optical bounce is reduced with increasing concentration of CNTs. When the applied frequency is changed to 10 Hz the optical bounces of CNT-doped TNLC cells are smaller than that of the pure LC cells.

並列關鍵字

twist nematic ； carbon nanotube ； backflow ； liquid crystal ； chiral homeotropic

參考文獻

[1] Pochi Yeh and Claire Gu, Optics of Liquid Crystal Displays (1999).

[2] Sumio, “Helical microtubules of graphitic carbon,” Nature, 354, 56–58 (1991).

[3] R. Saito, M. Fujita, G. Dresselhaus, and M. S. Dresselhaus, “Electronic structure of chiral graphene tubules,” Appl. Phys. Lett., 60, 2204–2206 (1992).

[4] D. W. Berreman, “Dynamics of liquid-crystal twist cells,” Appl. Phys. Lett., 25, 12–15 (1974).

[5] C. Z. van Doorm, “Dynamic behavior of twisted nematic liquid-crystal layers in switched fields,” J. Appl. Phys., 46 3738–3745 (1975).