摻雜奈米粒子對高分子分散型液晶光電特性之影響探討

Electro-Optical Properties of Nanoparticle-Doped Polymer Dispersed Liquid Crystals

林孟頡(Meng-Jie Lin)

指導教授 ： 徐芝珊

中原大學/理學院/物理研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100126

摘要

高分子分散型液晶為具有光學異方性的液晶滴，均勻分散在高分子網絡中。在無外加電壓的情況下，因液晶與高分子折射率的不匹配，高分子分散型液晶因光散射而呈現霧狀。當外加電壓使液晶分子轉動至與電場平行的方向後，此時入射光因液晶滴與高分子的折射率相近而穿透。因此可藉由調控外加電場，改變液晶滴與高分子間折射率的關係，造成光散射與光穿透狀態。
　　在本研究中，我們探討高分子分散型液晶的閾值電壓以及液晶滴大小在摻雜二氧化鈦、鈦酸鋇以及四氧化三鐵等奈米粒子後的改變；在摻雜奈米粒子後，閾值電壓幾乎皆下降；但前兩者在摻雜濃度過高時會使閾值電壓下降的情形減緩，而四氧化三鐵在我們研究的濃度範圍內無此現象產生；在液晶滴大小方面，摻雜二氧化鈦以及鈦酸鋇對液晶滴大小的影響較不明顯，但摻雜四氧化三鐵後，液晶滴大小有明顯的改變。最後我們將探討液晶滴變化與奈米粒子摻雜濃度對閾值電壓之影響。

關鍵字

高分子分散型液晶 ； 液晶滴

並列摘要

Polymer dispersed liquid crystal (PDLC) are the polymer matrixes uniformly dispersed with liquid crystal droplets. When there is no electric field, PDLC appears to be white due to the mismatched refractive index of polymer and LC droplet, therefore the light is scattered from the droplets. When an electric field is applied across the cell, the LC molecules rotate to the direction of the electric field, and the PDLC is transparent. The opaque and transparent states can be switched by the external electric field through the changes of the refractive index of the LC droplet.

　　In this thesis, we have investigated the influence of doping nanoparticals, such as Titanium dioxide, Barium titanate and Iron oxide, on the threshold voltage and the LC droplet size of PDLC. Doping nanoparticle Titanium dioxide and Barium titanate in the PDLC, the threshold voltages decrease and are saturated when the doping concentration increases. However, the size of LC droplet does not change obviously. This phenomenon is quite different when Iron oxide nanoparticles are doped in the PDLC, the changes of threshold voltage are not observed in our study and the LC droplet size is changed apparently. Finally we analyze the changes of the threshold voltage through the changes of droplet size and nanopartical concentrations.

並列關鍵字

liquid crystal droplet ； polymer dispersed liquid crystals

參考文獻

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