Transparent structured conductive coating for applications in smart windows

Solar radiation reaching the surface of the earth for a period of one hour contains more energy than that consumed by mankind over an entire year. Some of this solar energy is already collected by photovoltaic cells to cover the electricity needs of buildings but the most dominant part of the total energy consumption is space heating. This thesis explores ways of efficiently using solar radiation that penetrates buildings' windows to intelligently manage indoor temperatures and reduce the need for indoor heating. Energy-efficient windows are already being used to increase the thermal insulation of a façade. Such insulating windows contain an ultra-thin, multilayered, transparent silver coating that acts as an infrared mirror which significantly reduces thermal losses that occur through radiation from inside the building. These so-called low-emissivity coatings revolutionized the field of building insulation since the early '80s, but also come with some drawbacks, such as (i) decreased solar heat gain coefficient which reduces the potential for energy savings during winter; (ii) lack of adjustability in reflectivity/heat retention during different seasons; and (iii) the metallic nature of the coating negatively affects signal transmission of modern telecommunication. The purpose of this work is to explore what properties can be achieved by laterally structuring a coating or multilayer and investigate how these novel properties can be exploited in various applications for window glazing in buildings. It is shown that, by structuring the coating into a patch array, it acts as a high-pass filter and makes a window more transparent to microwaves. In contrast, a wire mesh behaves as a low-pass filter, creating a glazing that selectively lets in solar radiation. Finally, the ability of modulating the transparency of window glazing according to seasonal variations in solar radiation is demonstrated using large-band electrochromic windows that can adapt the color of the glass depending on the situation. These technologies are expected to contribute to the development of optimized electrochromic window that modulates solar heat gains and daylight inside buildings, enabling also to reduce indoor space heating energy needs.