Liquid Crystals and Polymers in Application of Opto-Electronic Devices

• Main Authors: Li-Chen Huang, 黃麗真
• Other Authors: Chih-Yu Chao
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/09335018955268470858

博士 === 國立臺灣大學 === 物理研究所 === 100 === Novel materials, liquid crystals, photopolymers and conducting polymers, have many significant applications in micro optics, organic photovoltaic (OPV) cells and liquid crystal displays (LCD) manufacturing. In this dissertation, we successfully fabricate polymer microlens arrays and polymer solar cell devices by using these materials and investigate the electric, optical and physical properties to characterize their several advantages and vantages in the future position for optoelectronic devices. At first, a low-temperature self-assembly method using phase separation is demonstrated for the first time to fabricate polymer microlens arrays. In this study, we present a simple method of producing microlens arrays based on liquid crystal/photopolymer blends phase separation. The morphology of the microlens arrays has been measured by SEM, AFM and scanning white light interferometer. Our results show that the microlens arrays obtained from our experiments have a comparable light-gathering capability and can be applied in optical systems. In the latter, there are two topics concerning polymer solar cells. The first one is “Self-Assembled Multilayers Modified ITO in Polymer Solar Cells by Soft-Imprinting”. In this work, surface modification of indium tin oxide (ITO)-coated substrates through the use of self-assembled multilayers by the soft-imprinting method has been applied to adjust the anode work function and device performance in polymer solar cells based on a P3HT:PCBM heterojunction. The efficiency and morphology of the solar device with CF3-terminal group materials as a buffer layer have been measured and investigated. These results demonstrate that the soft-imprinting method is an effective and rapid procedure that enhances the quality of polymer solar cells and indicates potential implications for other organic devices containing an interface between a blended organic active layer and an electrode layer. In the second topic, we represent a fascinating approach – the rubbing method – to produce periodic grooves of PEDOT:PSS layer and apply it in polymer solar cells based on a P3HT:PCBM heterojunction. The 500 nm wide and 10 nm deep grating-like features have a profound effect on carrier mobility, light trapping and hole collection efficiency, leading to an increase in the short circuit density, filling factor and power conversion efficiency. These results indicate the feasibility of the rubbing method which is applicable to high-efficiency OPV cells.