含碳奈米添加物之高分子聚合物分散型液晶的光電特性

Electro-Optical Properties of Polymer-Dispersed Liquid Crystals Doped with Carbon Nanosolids

蔡佑哲(You-Jhe Tsai)

指導教授 ： 李偉

中原大學/理學院/應用物理研究所/碩士(2006年)

https://doi.org/10.6840/CYCU.2006.00435

摘要

高分子分散型液晶中因液晶與高分子的折射率不匹配，因此在無外加電壓的狀態具有光散射的特性，而當電壓開啟後因小滴裡的液晶導軸均朝著單一方向排列，使液晶與高分子的折射率相互匹配，進而降低光散射現象而呈現透明態。這樣的元件不需要配向層、偏光板，並且具有應用在大面板與可撓式面板的潛力。
在本研究中，我們參考文獻所提供的液晶與高分子比例，製作出具有強烈光散射特性的高分子分散型液晶，並利用自動量測系統觀察其光電特性。結果顯示樣品的幾項特性：一、因高分子的關係，樣品的閾值電壓與驅動電壓較純液晶高。添加碳60後能有效降低閾值電壓，但驅動電壓卻會增加；二、高分子含量越多，其光電性質對於頻率的變化越敏感，但碳60的添加會稍稍降低樣品對頻率的敏感度；三、添加碳60能有效地減少高分子分散型液晶的整體反應時間；四、添加碳60會極微量改變樣品的折射率，並且使聚合後的液晶球滴變大，因此降低了光散射的效果，卻也減弱樣品的軸外光暈效應。

關鍵字

高分子聚合物分散型液晶 ； 光電特性 ； 碳奈米雜質

並列摘要

Since the refractive index of polymer does not match that of liquid crystals in the polymer dispersed liquid crystal (PDLC) model, a light scattering phenomenon can be obtained in the absence of an electric field. On the contrary, the refractive index of polymer matches that of liquid crystals for a uniform direction of liquid crystals within each droplet in the presence of an electric field, meanwhile, reduction of light scattering can be attained and so the PDLC bulk achieves a transparent state. This promising device can be applied to large and flexible display panels without the need for alignment layers and polarizers.
The suitable concentration of prepolymer to liquid crystal is investigated in the relevant literature to possess significant light scattering and then one can observe the electro-optical effect by employing an automatic measurement system (AMS). Experimental results show that the PDLC researched in the present thesis possesses the following characteristics: Firstly, threshold and driving voltage of the PDLC bulk is larger than that of intrinsic LC bulk due to the polymer doping of LC. A reduction of the threshold voltage can be obtained by adding C60 into the PDLC as a dopant. Secondly, if more prepolymer is added into the PDLC for a higher concentration, then a higher sensitivity to the variation of frequency results. The reduction of sensitivity to the variation of frequency can be obtained by adding C60 into the PDLC. Thirdly, PDLC doped with C60 can effectively reduce total response time in comparison with that of pure PDLC. Fourthly, the degradation of the off-axis haze phenomenon can be obtained while the effective refractive index of the PDLC doped with C60 is modified, furthermore, larger domains formed by the curing process relatively reduce the light scattering effect.

並列關鍵字

polymer-dispersed-liquid-crystal ； carbon nanosolids ； elecro-optical properties

參考文獻

參考文獻

[1] K. Takatoh, M. Hasegawa, M. Koden, N. Itoh, R. Hasegawa, and M. Sakamoto, Alignment Technologies and Applications of Liquid Crystal Devices (Taylor & Francis, London, 2005).

[2] I. Dierking, “Relationship between the electro-optic performance of polymer-stabilized liquid-crystal devices and the fractal dimension of their network morphology,” Advanced Materials 15(2), 152–156 (2003).

[3] Y. Q. Lu, F. Du, Y. H. Lin, and S. T. Wu, “Variable optical attenuator based on polymer stabilized twisted nematic liquid crystal,” Optics Express 12(7), 1221–1227 (2004).

[4] S. H. Kim and L. C. Chien, “Electro-optical characteristics and morphology of a bend nematic liquid crystal device having templated polymer fibrils,” Japanese Journal of Applied Physics 43(7B), 7643–7647 (2004).