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研究生:王建生
研究生(外文):Chien-Sheng Wang
論文名稱:含二氧化矽或四氧化三鐵奈米顆粒之90o扭轉向列型液晶元件的光電特性研究
論文名稱(外文):Electro-optical Properties of Twisted Nematic Liquid Crystal Doped with SiO2 and Fe3O4 Nanoparticles
指導教授:趙治宇
指導教授(外文):Chih-YU Chao
學位類別:碩士
校院名稱:國立臺灣大學
系所名稱:物理研究所
學門:自然科學學門
學類:物理學類
論文種類:學術論文
論文出版年:2006
畢業學年度:94
語文別:英文
論文頁數:87
中文關鍵詞:摻雜二氧化矽四氧化三鐵扭轉向列型液晶
外文關鍵詞:dopedSiO2Fe3O4twisted nematic liquid crystal
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  • 收藏至我的研究室書目清單書目收藏:1
在本篇論文中,此研究的主要目的在於觀察並且比較摻雜二氧 化矽或四氧化三鐵奈米顆粒的九十度扭轉向列型液晶晶胞之光電行為特性。在摻雜的液晶晶胞裡面,主要包含了向列型的液晶以及少
量的二氧化矽以及四氧化三鐵奈米顆粒。在實驗過程中,我們對這
些液晶晶胞做了一系列的光學量測,像是穿透率、反應時間、電容
以及離子效應分別在直流以及交流電壓下對於液晶晶胞的影響。實
驗結果顯示,在九十度扭轉向列型液晶晶胞裡適當的摻雜一些奈米
顆粒可以有效的降低液晶在電壓頻率為1 kHz、500 Hz以及100 Hz的閥值電壓以及驅動電壓。並且實驗結果也指出,在液晶晶胞裡的
介電係數的異方性會隨著雜質的添加而加大,此部份在電容的量測
方面可得到證實。此外,除了液晶的驅動電壓以及閥值電壓受到改
變外,液晶晶胞裡的離子效應也有被減弱的趨勢,同樣地也會直接
造成液晶驅動電壓以及閥值電壓的降低。而至於在反應時間方面,
由於摻雜的二氧化矽或是四氧化三鐵奈米顆粒會造成液晶晶胞的黏滯係數增大,而其增加的幅度又比介電係數的異方性以及閥值電壓
的減少來的大,所以在上升時間以及下降時間上所表現出來的結果
都比沒有摻雜的晶胞來的大,故液晶晶胞在反應時間的表現上就顯
得相當緩慢。
The main purpose of this thesis is to investigate the optical properties of SiO2-doped or Fe3O4-doped 90o twisted nematic liquid crystal (TN-LC) cells. The doped cells comprise both a nematic host and a minute amount of SiO2 or Fe3O4 nanoparticles. We measured their transmittance, response time, capacitance and ion effect in the presence of ac and dc voltage. Experimental results indicate that doping some impurities in LC cell can reduce the Vth for 1 kHz, 500 Hz, and 100 Hz voltage. It is experimentally proved that SiO2 or Fe3O4 nanoparticles modify the dielectric anisotropy and the viscosity of the doped liquid crystal cells, hence significantly modifying the threshold voltage and the switching behavior of a liquid crystal device. Besides the transmittance and the threshold voltage, the ion effect of the doped TN-LC cells is also reduced. Since the ion effect is decreased, the threshold voltage is of course reduced. The doped SiO2 or Fe3O4 nanoparticles also increase the viscosity of the doped TN-LC cells. Therefore, the rise time and the fall time increase when the doped concentration increases due to the increase in the viscosity of the doped TN-LC cells.
致謝 I
摘要(中文) II
ABSTRACT III
CONTENT IV~VII
LIST OF FIGURES VIII~XI
LIST OF TABLES XII~XIII

CHAPTER 1.
Introduction 1~16
1.1 Introduction of Liquid Crystals 1
1.2 General Types of Liquid Crystals 1
1.3 Some Properties of Liquid Crystals 4
1.3.1 Orientational Order Parameter 4
1.3.2 Dielectric Anisotropy 4
1.3.3 Refractive Index Anisotropy 5
1.3.4 Elastic Constants 7
1.3.5 Viscosity 9
1.3.6 Surface Alignment and Rubbing 9
1.3.7 Pretilt Angle 13

CHAPTER 2.
Liquid Crystal Display Modes 17~28
2.1 Twisted Nematic Liquid Crystal Display 17
2.1.1 Introduction of Twisted Nematic Liquid Crystal 17
Displays (TN-LCDs)
2.1.2 Transmissive TN Cells 18
2.1.3 Operating Principle of a 90o TN-LCD 19
2.2 Super Twisted Nematic Liquid Crystal Display 24
2.2.1 Introduction of Super Twisted Nematic Liquid
Crystal Display 24
2.2.2 STN Effect 25

CHAPTER 3.
Doping Materials 29~34
3.1 SiO2 Nanoparticles 29
3.1.1 Key Properties of SiO2 30
3.1.2 Electronics Industry 31
3.2 Fe3O4 Nanoparticles 34

CHAPTER 4.
Experimental Methods 35~56
4.1 Basic LCD Components 35
4.2 Sample Preparation 37
4.3 Experimental Processes 40
4.3.1 Some Measurements 40
4.3.2 Measurement of the Electro-Optical Switching Curve45
4.3.3 Measurement of the Response Time 47
4.3.4 Measurement of the Viscosity 48
4.3.5 Measurement of the Capacitance 51
4.3.6 Measurement of the Ion Effect 52

CHAPTER 5.
Results and Discussion 57~86
5.1 Measurement Results of Transmittance 57
5.2 Measurement Results of Response Time 65
5.3 Measurement Results of Viscosity 70
5.4 Measurement Results of Capacitance 80
5.5 Measurement Results of Ion Effect 84

CHAPTER 6.
Conclusion 87
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References of Chapter 2

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References of Chapter 4

[1] M.T. Hsu, Master Thesis, N.C.U., Taiwan (2003).

[2] M. Imai, H. Naito, M. Okuda, and A. Suginura, “Determination of rotational viscosity of nematic liquid crystals from transient current: Numerical analysis and experiment,” Jpn. J. Appl. Phys. 38, 3482–3487 (1994).

[3] A. Sugimura, N. Matsui, Y. Takahashi, H. Sonomura, H. Naito, and M. Okuda, “Transient currents in nematic liquid crystals,” Phys. Rev. B 43, 8272–8276 (1991).


[4] Po-Lun Chen and Shu-Hsia Chen, Jpn. J. Appl. Phys. 39, L297-L299 (2000).

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[9] S. Mino, E. Takeda, Y. Nanno, T. Kawaguchi, Y. Mino, A. Otsuka and S.-I. Ishihara: Proc. SID 20, 242 (1989).

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[13] H. De Vleeschouwer, F. Bougrioua and H. Pauwels, Mol. Cryst. Liq. Cryst 360, pp. 29-39 (2001).

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[16] A. R. M. Verschueren, P. A. E. J. Machiels, SID Digest, 50.3, pp. 1386-1389 (2003).


[17] B. Maximus, C. Colpaert, A. De Meyere and H. Pauwels, Liq. Cryst.,15, pp. 871-882 (1993).

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References of Chapter 5

[1] Akihiko Sugimura, Yutaka Takahashi and Ou-Yang Zhong-can, Jpn. J. Appl. Phys. 32, pp. 116-128 (1993).

[2] W. Lee, C.–Y. Wang, Y.-C. Shih, Appl. Phys. Lett. 85, 513 (2004).
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