Operating methods of high voltage bistable smart glass electronics systems: Summary of the doctoral thesis

Liquid crystal displays (LCDs) have been used by mankind on a daily basis for decades, but the demand for their integration and development of new products is only growing. One of the research directions is smart glass/windows, and, although they are known for more than 25 years, there are areas that still need to be researched. This Thesis focuses on Smectic-A (SmA) liquid crystals’ (LCs) functional behaviour in order to understand if this will be the next generation product that could improve society’s daily life. An in-depth literature review discusses existing studies, obtained experimental data and attempts to develop functional products. The main unresolved problems are highlighted, described in detail and solutions are offered. The SmA LC is able to maintain two stable optical states: transparent and light scattering, without additional energy resources, allowing to save electricity costs. The optical properties of this liquid crystal are by far the best compared to the products available in the market, i. e. the light transmittance in transparent state is 85+ % and in scatter state < 2 %. Enabling the LC to be used for a variety of purposes, such as smart windows to scatter light on a sunny day or provide a sense of privacy in an open type office space. In order to understand the potential of SmA LC in the smart glass/window technology, analysis of existing products was performed, a summary of an active smart glass/windows provided and a comparative study between them was made. In addition, an in-depth study of long-term functional stability was performed, during which the most popular types of defects were listed and analysed. Solutions for defect elimination and recommendations for optimization of switching systems and production processes are provided. A methodology for determining the electrical parameters of an LC has been developed in order to create an electrical simulation model and facilitate the development of electronic switching systems. The results of the work are summarized and recommendations for the functional use of SmA LCs of various designs and sizes are provided.