表面配向對聚合物穩定藍相液晶之晶體成長與電光特性的影響

Abstract

聚合物穩定藍相液晶具有自組晶體結構、電場衍伸雙折射性(克爾效應) 、反應速度快、不需配向層等優點，因此近年來有許多光電元件應用如顯示器、光子晶體雷射、液晶透鏡、和光開關等。聚合物穩定藍相液晶的自組晶體結構會影響電光特性，然而，聚合物穩定藍相液晶的長晶物理機制仍不清楚，本論文討論表面配向對聚合物穩定藍相液晶之長晶與電光特性的影響，並且對遲滯效應的成因作進一步的探討。由實驗觀察，表面配向方式與表面對藍相液晶的親疏性(affinity) 影響晶體初期之成核大小與轉向(orientation)，因而決定最終聚合物穩定藍相液晶形態的晶格大小和晶格轉向。此外，聚合物穩定藍相液晶之遲滯效應與晶格大小相關，利用邊界條件的控制，我們能控制晶格大小並改善遲滯效應。依此研究我們可藉由控制長晶以設計更多的聚合物穩定藍相液晶之光電元件如相位調制器與振幅調制器。

Polymer-stabilized blue phase liquid crystal (PSBP-LC) has many advantages, such as self-assembly lattice structure, electrically induced birefringence, fast response time, and alignment layer-free. It has many applications in electro-optical devices, such as displays, photonic crystal lasers, liquid crystal lens, and optical switches. The self-assembly lattice structure of PSBP-LC has an influence on its electro-optic properties. However, the physical mechanism of crystal growth of PSBP-LC is still unclear. In this research, we discuss the effect of surface alignmnet to the crystal growth of PSBP-LC and its electro-optic properties, and discuss the factors to hysteresis. From experimental observation, surface alignmnet and the affinity between liquid crystal and the substrate would affect the sizes and orientations of the initial crystal growth of PSBP-LC, and decide the sizes and orientations of final crystal morpholoy. Besides, the hysteresis of PSBP-LC has a relation with the domain size. Controlling the boundary condition, we can control the domain size and improve the hysteresis problem. According to the research, we can design more PSBP-LC applications such as phase or amplitude modulators by controlling the crystal growth.