| Summary: | 碩士 === 國立臺灣大學 === 物理研究所 === 96 === 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.
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