| dc.description.abstract | Liquid crystal (LC) technology is getting maturer and maturer nowadays due to its technological development. Many scattering mode LC light modulators are adopted to the application of smart windows. Among them, polymer dispersed LCs (PDLCs) is the most famous technique for such applications. Regarding the fabrication processes, phase separation of LCs and polymers by illuminating with UV light or heating is the most important approach. Additionally, the switching of the light modulator between transparent and scattering modes by applying an external electric field is also achieved. However, most of the scattering mode LC light modulators consume too much power to be suitable for practical application due to the continuous application of electric field. Restated, it causes large power consumption. Accordingly, bistable and multi-stable scattering mode LC light modulators have been paid much attention recently.
This study presents an electrically switchable and permanently stable scattering mode LC light modulator by dynamic fingerprint chiral textures (DFCT). According to the experimental results, stable transparent and scattering modes can be switched between each other after an electric field with different frequencies is applied. To the best of our knowledge, electrically switchable DFCT is demonstrated for the first time in this system. In this thesis, the following three parts, including (1) the definition of DFCT and its electric switching mechanism, (2) the electro-optical properties of electrically switchable DFCT, and (3) the comparison of the electro-optical properties between the other chiral materials and the causes for stabilization of DFCT, will be discussed in detail. Briefly, the main mechanism is the switching between large and small domains of DFCT by applying an electric field with different frequencies. With the application of electric field having high (low) frequency, the LC light modulator presents transparent (scattering) state due to the formation of large (small) domains of DFCT. Besides, the required amplitude to switch the light modulator from a scattering (transparent) state to a transparent (scattering) state decreases as the frequency of the applied electric field increases (decreases). In addition to the permanent stabilization after the applied field is switched off, such a LC light modulator has some other advantages, such as polarization-independent scattering, unlimited viewing angle in transparent mode, and others. Consequently, this study presents a scattering mode LC light modulator with the advantages of electrical switching, permanent stabilization, wide viewing angle, high contrast, low driving voltage, and so on. Considering the practical applications of LC devices, it is believed that such novel textures, DFCT, can be adopted to develop displays, e-books, e-papers, etc. | en_US |