Abstract
The objectives of this research are the preparation and characterization of negative dielectric anisotropic liquid crystal (LC)/ polyhedral oligomeric silsesquioxanes (POSS) mixture that works as a substitute to the alignment layer for flexible displays. There are four parts in this dissertation.The first part of this dissertation investigated the nanoparticles in the LC cell, which can exhibit the properties of vertical alignment without using alignment layers. The electro-optical properties of this nanoparticles-induced vertical alignment in the LC cell are very similar to the conventional homeotropic LC cell by using alignment layers. But it drives the manufacturing technology of flexible LC toward low temperature process.The second part of this dissertation compared electro-optical properties of a flexible photo-spacer LC cell using amorphous PC substrates and a flexible bead-spacer LC cell using crystalline biaxially oriented PET substrates. Both types of flexible devices adopted the NIVA effect to align the LC cell without using alignment layers. Comparing to bead-spacer LCD, the photo-spacer LCD showed higher mechanical stability against external bending and a more reliable fabrication process.The main objective of the third part of this dissertation is to examine the alignment ability of POSS films. The polar anchoring energy of a negative nematic liquid crystal (MLC-6882) aligned on POSS films were measured and calculated from the effective cell gap method. The alignment mechanism was inferred by contact angle, FTIR, and AFM studies. The absoption of the POSS particles on the ITO surface together with the interaction between LC molecule and POSS particles may be the major driving force to vertically align the LC and realize this alignment layer free technology.The final part of this dissertation used NIVA method to fabricate a guest-host liquid crystal display (GH-LCD). This GH-LCD exhibited a high reflectance of ~59% in the voltage-off state and a low threshold voltage of ~2.0V. Finally, the same technology was used to fabricate a flexible timepiece.