複製成形法製備溝槽結構之應用

Abstract

溝槽結構的製造和應用在顯示器、光電、電子工業一直很受到重視，其中一個理由是因為溝槽具有導引分子的功能。而有序分子在光電、電子元件等領域中具有很重要的應用前景。過去的方式通常是將細微溝槽製造在高分子薄膜上(摩擦或是光學微影)來配向分子。但是這樣的方式可能會產生靜電、灰塵，或者製程相對複雜，而且應用到可撓式元件上時，其多層結構也可能會有脆裂的問題。 在本研究中，我們使用複製成形法，直接將奈米溝槽轉印到軟性高分子基板上，來改進脆裂的問題，不同以往的高分子薄膜，我們是讓基板本身就具有配向液晶分子的功能，做出不需額外配向層的可撓式扭轉向列型液晶元件。 此外，應用液晶會受到溝槽導引的特性，我們還發展出一個簡單的方法來配向單軸分子。把液晶和染料分子同時摻入熱固型液態高分子裡，在複製成形的過程中，液晶分子會延著溝槽的方向排列，而染料分子就會受到液晶分子的導引而具有方向性。我們對經配向的染料分子做光致螢光光譜的量測，當偏振方向和溝槽方向平行時，螢光強度最大；兩者垂直的時候，螢光強度最弱，由此結果發現染料分子確實延著溝槽方向排列。光學吸收光譜的量測也支持這樣的結果。

A lot of attention has been paid to the fabrication and application of grooves in electro-optical display and electronic industry. One of the reasons is that grooves can be used to control the alignment of molecules. The alignment ability of molecules has shown potential for applications in electro-optical and electronics industries. Traditionally, Grooves are often fabricated on thin polymer films via rubbing or photolithography to align molecules. However, dust and static charges can be introduced through these manufacturing processes and they are relatively complicated. Moreover, when we apply them to flexible devices, the multi-layer configurations may crack. In this thesis, we transfer the microgroove patterns onto the Poly(dimethylsiloxane) (PDMS) substrate to avoid the cracks by means of replica molding method. Different from traditional polymer alignment layers, the bendable materials serve not only as substrates but also as alignment layer; thus, we successfully fabricated the flexible alignment-layer free twisted nematic liquid crystal cell. By means of the character that liquid crystal can be guided by grooves, we also developed an easy approach to align uniaxial molecules. The uniaxial molecules and liquid crystal molecules are mixed with the PDMS. During the cured process, the liquid crystals are oriented along the grating direction, and the uniaxial dye molecules are oriented by liquid crystal. In the photoluminescence measurement, the luminescence intensity is strongest when the grating direction of the samples is parallel to the polarization direction of polarizer and weakest when the grating direction of the samples is perpendicular to the polarization direction of polarizer. It shows that the molecules have macroscopic anisotropic orientation. The measurements of optical absorption spectrum also support the results.