Fabrication of large area micro-, nanopatterns by defect-assisted liquid crystalline structures and their applications in opto-electronics

Abstract

Large area ordered structure by organic molecular soft building blocks is one of the most exciting interdisciplinary research areas in current materials science and nanotechnology. Directed self-assembly of soft condensed matter such as block copolymers, supramolecules, surfactants, colloids, and liquid crystals (LCs) have been massively studied to get very periodic and defect free structures for the potential application of micro-fabrication. In this thesis, the new types of liquid crystal defects array are introduced for the first time and can be forming highly ordered array controlled by several methods which are including surface treatment, micro-size confined system, external field and thermal annealing. The origin and the behavior of LC defect structures are described based on liquid crystal physics and brand new defect structures of smectic liquid crystal are introduced for the first time in liquid crystal research field and are described by theoretical approach. The unique defect structures are investigated by convolution methods between various microscopic techniques - polarized optical microscope (POM), fluorescence confocal microscope (FCM), scanning electron microscope (SEM), transmission electron microscope (TEM) and atomic force microscope (AFM) and scattering methods - X-ray diffraction (XRD) and small angle neutron scattering (SANS). The present findings at here pose new theoretical challenges and potentially open the way for lithographic applications based on smectic liquid crystalline materials. As a potential application, the highly ordered LC defect arrays can be used for various lithographic templates such as photolithographic mask, microlens array and superyhydrophobic surfaces The thesis consists of eight chapters. At first, Chapter 1 of “introduction” section briefly explain and overview about whole researches in this thesis. Chapter 2, 3 and 4 introduce the study of periodic smectic liquid crystal defect structures, such as toric ...