Application of Nanoparticles-Induced Vertical Alignment on Liquid Crystal Microlens

• Main Authors: Yi-Ming Shieh, 謝一鳴
• Other Authors: Shie Chang Jeng
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/20981913347021924699

碩士 === 國立聯合大學 === 光電工程學系碩士班 === 97 === In this thesis, we investigated the nanoparticles of polyhedral oligomeric silsesquioxane (POSS), which can induce vertical alignment (VA). In our experimental, POSS nanoparticles were spin-coated on the ITO substrates, as well as then melted and rubbed to improve the shortcomings of POSS/LC mixture directly injected into cell. This spin-coated and rubbed POSS films can improve the preferred direction and stability of the director profiles of nematic liquid c rystals under the applied voltage. The electric and optical properties were investigated using the dependence of the phase retardation, transmittance, and capacitance measurements on the applied voltages, respectively, which can provide the detailed information of the impacts of POSS on the voltage-induced reorientation of the liquid crystal molecules. The analysis includes the contrast, response time and anchonring energy, which critically depend on the different process conditions. In this work, we apply the different functional group of POSS and various process conditions to investigate the nanoparticles-induced alignment mechanism of liquid crystals. Furthermore nanoparticles-induced vertical alignment (NIVA) of the nematic liquid crystals (LC) was proposed to make a tunable liquid-crystal flat microlens with hybrid-aligned nematic (HAN) mode, which was fabricated using micro-dropping technique. The spatially varying director orientation and the lenslike distribution of refractive index appears in the NIVA LC layer with concentric non-uniform distribution of the refractive index was then formed. The focus effect and its voltage-dependent focal length of this flat LC lens were observed.