臺灣博碩士論文加值系統

非接觸式液晶配向技術近年來越發盛行，利用此技術可避免機械摩擦 或高溫烘烤等所產生的損耗。於西元 2005 年，夏普公司發現將奈米離子 Polyhedral Oligomeric Slisesquioxanes (POSS)摻雜於液晶中可得到液晶分子 垂直配向排列，自此開始，許多研究團隊便著手研究此類型液晶配向材料， 欲將成本降低並提高其均勻度。
本論文中所使用的離子性材料(C-R8NOH)與 POSS 同樣擁有以低濃度 混入液晶中，並注入表面僅有 ITO 導電膜的液晶空盒中即可得液晶垂直配 向排列的特性。研究中根據液晶材料的物性，可利用不同濃度及注入溫度得 到不同液晶分子排列的液晶盒，論文中使用不同種類的液晶材料，以該實驗 結果推測 C-R8NOH 之擴散型態，且因摻雜濃度較低，故不將 C-R8NOH 對 整體材料物性的影響加入討論。經多次實驗得知，在混合物溫度控制於超過 該液晶相變溫度時注入液晶空盒，注入過程中混合物之擴散係數相對較高， 故 C-R8NOH 易雜亂堆疊於基板上使液晶盒產生散射態;若將混合物溫度控 制於未達該液晶相變溫度時，則因擴散係數相對較低，C-R8NOH 可均勻地 吸附於基板上，故較容易得到液晶均勻的垂直配向排列。此外，於基板上塗 佈不同表面配向材料(如 PI, PVA 等)製成液晶空盒，將摻雜 C-R8NOH 的液 晶混合物注入該液晶空盒，將由於 C-R8NOH 於不同配向材料上的表現不 同，故所得結果不同。值得一提的是若將上述配向膜進行摩擦配向，當利用
I
溫度控制混合物處於低擴散係數時注入該液晶空盒，則 C-R8NOH 會平行於 摩擦配向方向吸附在配向膜上，另因其 3D 結構的影響而提供液晶分子排列 偏離原水平配向膜 10o。有關 C-R8NOH 離子性材料的電性，經實驗發現在 施加適當直流電壓後可將 C-R8NOH 分離為正離子及負離子，並分別吸附在 負電極與正電極上，且因該離子之長鏈結構，故使液晶分子隨之排列成垂直 配向。

The mechanical rubbing process is a common approach to obtain homogeneous alignment for liquid crystals (LCs) because of its simplicity, thermal stability and low-cost. However, the mechanical damages could be generated through such a contact process to degrade the display performances and production yields. Hence, in the past decades, several non-contact alignment techniques have been studied and developed widely. In 2005, Sharp has successfully demonstrated a non- contact solution to align LCs vertically in a nanoparticle doped LCs (NPdLCs). The NPs can spontaneously adhere onto the substrates to generate vertical alignment anchoring due to their special structures. The manufactures can omit the LC alignment processes to enhance the production rate.
In this thesis, the feasibility to approach a variety of LC alignments in ionic nanoparticle doped LCs (INPdLCs) has been successfully demonstrated. The LC alignments generated by INPs are strongly dependent on the concentration of the INPs and the temperature of INPdLCs. As the sample of INPdLCs is heated to the temperature higher than its clearing temperature, the diffusion rate of INPs toward the indium-tin-oxide (ITO)-coated substrates is relatively high because of the low viscosity of the LC mixture. Accordingly, considerable INPs do randomly adhere onto the ITO-coated substrates to produce random alignment anchoring. The LC multi-domains generate due to the massive accumulation of disordered INPs adhered onto the ITO-coated substrates. Hence, the incident lights are scattered because they encounter different refractive indices of each LC domain through whole LC bulk. On the other hand, as the temperature of the INPdLCs sample is lower than its clearing temperature, the diffusion rate of INPs toward the substrates is relatively low. The INPs can homogeneously adhere onto the ITO-
III
coated substrates and produce uniformly vertical alignment anchoring.
Furthermore, different LC alignments can be obtained as the INPs adhere onto different coatings, such as polyimide, PVA, etc., onto the ITO-coated substrates. The INPs generate the homogeneous alignment force as they adhere onto the substrates coated with unidirectionally rubbed polyimide. Interestingly, the angle between the homogeneous alignment anchoring and the rubbing direction of polyimide/PVA was experimentally measured to be about 10o. A model will be given to elucidate the experimental results in this thesis. Moreover, the electrochemistry of the INPdLCs was also investigated. Each INP is composed of one positive ion and one negative ion. They can be separated as a suitable DC voltage is applied. The positive (negative) ions diffuse across the bulk and adhere onto the negative (positive) electrode to produce vertical alignment anchoring, generated by the long side-chain of the positive and negative ions. In other words, the initially homogeneous LC alignment can be electrically switched to vertical one. The proposed results have also been confirmed according to the direct evidences obtained by mass spectrometry.

中文摘要 ................................................................................................................ I Abstract .............................................................................................................. III 誌謝 ...................................................................................................................... V
目錄 ..................................................................................................................... VI 表目錄 ................................................................................................................. IX 圖目錄 .................................................................................................................. X 符號說明 .......................................................................................................... XIX
第一章 緒論.........................................................................................................1
§1-1 前言........................................................................................................ 1
§1-2 研究動機...............................................................................................1
§1-3 論文架構...............................................................................................2
第二章 液晶簡介................................................................................................. 4
§2-1 液晶導論................................................................................................ 4
§2-2 液晶定義................................................................................................ 4
§2-3 液晶分類................................................................................................ 5
§2-4 液晶光電特性...................................................................................... 12
§2-4-1 折射率異向性(Birefringence) .......................................................... 12
§2-4-2 溫度對向列型液晶的影響 ................................................................. 17
§2-4-3 連續彈性體理論(The elastic continuum theory).......................17
§2-4-4 介電異向性(Dielectric anisotropy).................................................19
第三章 相關理論介紹....................................................................................... 21
§3-1 表面配向膜.......................................................................................... 21
§3-2 黏滯係數(Viscosity coefficient) ......................................................... 22
§3-3 擴散係數(Diffusion coefficient) ........................................................ 23
§3-4 電泳動原理(Electrophoresis)[25] ........................................................ 25
§3-5 Polyhedral Oligomeric Slisesquioxanes (POSS)奈米粒子 ............. 26
§3-6 羥基(OH)與二氧化錫(SnO2)間的吸引力........................................28
第四章 實驗方法與過程...................................................................................29
§4-1 樣品準備.............................................................................................. 29
§4-1-1 材料介紹..................................................................................................29
§4-1-2 液晶盒製作............................................................................................34
§4-2 實驗架構.............................................................................................. 38
§4-2-1 空液晶盒厚度量測 ............................................................................... 38
§4-2-2 垂直配向檢測法....................................................................................40
第五章 實驗結果與討論...................................................................................43
§5-1 離子性材料 C-R8NOH 在 ITO/PVA/PI 上的吸附.......................... 43
§5-1-1 摻雜於不同液晶之離子性材料 C-R8NOH 於不同溫度條件下 在 ITO 上的吸附 .................................................................................. 43
§5-1-2 離子性材料 C-R8NOH 在 PVA 上吸附特性之研究 ................ 61
§5-1-3 離子性材料 C-R8NOH 在 PI 上吸附特性之研究..................... 64
§5-2 電場引致離子性材料 C-R8NOH 在水平配向材料上的吸附效應 . 68 §5-2-1 外加直流電場.........................................................................................68
§5-2-2 外加交流電場.........................................................................................80
§5-3 探討利用離子性材料 C-R8NOH 控制液晶預傾角的特性 ............. 85
§5-3-1 施加不同時間直流電壓後的電壓-穿透曲線...............................86
§5-3-2 由液晶分子是否連續排列判斷預傾角是否存在......................91
VII
第六章 結論與未來展望...................................................................................94
§6-1 結論.....................................................................................................94
§6-2 未來展望.............................................................................................97
參考資料 ........................................................................................................... 101

M. Schadt, H. Seiberle, and A. Schuster, “Optical Paterning of multi-domain liquid-crystal displays with wide viewing angles,” Nature 381, 212-215 (1996).
[2] P. J. Bos and K. R. Koehler/Beran, “The pi-cell: A fast liquid crystal optical switching device,” Mol. Cryst. Liq. Cryst. 113, 329-339 (1984).
[3] Y. Iwamoto, Y. Toko, H. Hiramoto, and Y. Iimura, “
SID Symposium Digest
31, 902-905 (2000).
[4] W.-Z. Chen, Y.-T. Tsai, and T.-H. Lin, “Photoalignment effect in a liquid-crystal film
doped with nanoparticles and azo-dye,” Appl. Phys. Lett. 94, 201114 (2009).
[5] S.-C. Jeng, C.-W. Kuo, H. L. Wang, and C.-C. Liao, “Nanoparticles-induced vertical
alignment in liquid crystal cell,” Appl. Phys. Lett. 91, 061112 (2007).
[6] B. Bahoadur, Liquid crystals-applications and uses, (World Scientific Press, 1990).
[7] F. Reinizer, “Beitrage zur kenntiniss des cholesterins,” Monatsh. Chem. 9, 421-441 (1888).
[8] O. Lehmam, “Ü ber fliessende Krystalle,” Z. Phys. Chem. 4, 462-472 (1889).
[9] 陳言愈，電控及光控膽固醇液晶光柵之研究 (國立成功大學，碩士論文，民國 100
年).
[10] 松本正一，角田市良，液晶之基礎與運用 (國立編譯館，1996).
[11] H. Keller, “History of liquid crystals,” Mol. Cryst. Liq. Cryst. 21, 1-48 (1973).
[12] G. W. Gray, Thermotropic liquid crystals, (the Society of Chemical Industry 1987).
[13] W. H. de Jeu, Physical properties of liquid crystalline materials, (Gordon & Breach, 1980).
[14] H. S. Kitzerrow and C. Bahr, Chirality in Liquid Crystals, (Springer, New York, 2001).
[15] S. Chandrasekhar, B. K. Sadashiva, and K. A. Suresh, “Liquid-crystals of disc-like
molecules,” Pramana. J. Phys. 9, 471-480 (1977).
[16] A. Yariv, Optical Electronics in Modern Communications, (Oxford University Press, New
York, 1997).
[17] A. Yariv, Quantum Electronics, (Wiley, New York, 1988).
[18] P. Yeh and C. Gu, Optics of liquid crystal displays, (John Wiley & Sons, Inc., 2006).
[19] G. R. Fowles, Introduction to modern optics, 2nd ed., (University of Utah, 1975).
[20] I. C. Khoo and S. T. Wu, Optics and nonlinear optics of liquid crystals, (World Scientific,
1993).
[21] http://www.cv.ncu.edu.tw/data/FM/FM/FM1.pdf
[22] https://zh.wikipedia.org/wiki/%E9%BB%8F%E5%BA%A6#.E5.89.AA.E5.88.87.E9.BB
.8F.E5.BA.A6
[23] H. Löwen, “Anisotropic self-diffusion in colloidal nematic phases,” Phys. Rev. E 59, 1989-
1995 (1999).
[24] S. Link, W.-S. Chang, A. Yethiraj, and Paul F. Barbara, “Anisotropic Diffusion of
101
Improvement of Transmitted Light
Efficiency in SH-LCDs Using Quarter-Wave Retardation Films,”
Elongated and Aligned Polymer Chains In a Nematic Solvent,” J. Phys. Chem. B 110,
19799-19803 (2006).
[25] 陳建宏，摻雜二氧化矽奈米粒子之混合排列向列型液晶盒記憶特性探討 (國立彰化
師範大學，碩士論文，民國 99 年).
[26] 黃貞瑜，摻雜奈米粒子高分子膜之液晶配向及其應用之研究 (國立成功大學，碩士
論文，民國 99 年).
[27] J. Yue, X.-C. Jiang, and A.-B. Yu, “Adsorption of the OH-Group on SnO2(110) Oxygen
Bridges: A Molecular Dynamics and Density Functional Theory Study,” J. Phys. Chem. C,
117, 9962-9969 (2013).
[28] 許維婷，液晶盒厚度量測方法的研究 (國立成功大學，碩士論文，民國 93 年).
[29] S.-J. Hwang, S.-C. Jeng, and I-M. Hsieh, “Nanoparticle-doped polyimide for controlling
the pretilt angle of liquid crystals devices,” Opt. Express 18, 16507-16512 (2010).
[30] 施景仁，光控奈米金粒子的吸收研究 (國立中山大學，碩士論文，民國 98 年)
[31] H.-J. Li, J.-H. Wang, C.-S. Wang, P.-F. Zeng, P. Cai, Y.-J. Pan, and Y.-F. Yang, “Off-
resonant nonlinear optical refraction properties of azo dye doped nematic liquid crystals,” Opt. Express 6, 459-465 (2016).