Study on the Electro-optic Properties of Bistable Cholesteric Liquid Crystal Flexible Displays

• Main Authors: Hung, Chien-Li, 洪謙立
• Other Authors: Pan, Ru-Pin
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/14235672656402713276

碩士 === 國立交通大學 === 電子物理系所 === 101 === In order to develop flexible displays, we have studied a liquid crystal display mode with polymer-stabilized cholesteric texture, PSCT, that doesn't require polarizer, color filter or backlights. Therefore, the PSCT is low power consumption and attractive for bistable reflective display applications. In this study, we filled the mixture including a host nematic liquid crystal (MDA-003461), a chiral dopant (R-811), monomer (RM-257), and photo-initiator (DMPA) into anti-parallel cell. The cell was irradiated with UV intensity to polymerize the monomer, the PSCT with stable structure was formed. Then, we study on the electro-optic properties of PSCT samples with different ratio monomers and different irradiated UV light intensity. Experimental results show the contrast ratio decrease with higher monomer concentration or higher UV intensity, but the response time become faster. Therefore, we found three percent is the best monomer concentration and 0.2mW/cm2(15hr) is the best of UV intensity for those PSCT samples. Due to the typical single-layer PSCT structure can only reflect left- or right- circularly polarized light, the maximum of theoretical reflectance is 50% with low contrast. Therefore, we have used an anti-chiral double-layer PSCT structure to improve the reflectance and contrast. The double-layer PSCT structure reflects both left- and right- circularly polarized light, so the maximum reflectance can reach to 100% theoretically and the contrast ratio can also get promoted. The measured contrast ratio of the anti-chiral double-layer PSCT sample is nearly three times of that for a typical single-layer PSCT sample. Finally, we have also successfully transferred the PSCT display technology from glass substrates to flexible substrates.