Inorganic gel and liquid crystal based smart window using silica sol-gel process

- GDLC samples showed low scattering behavior and clear colorless state, compared with conventional PDLC.
- Response time of GDLC was 10 times shorter than PDLC.
- GDLC mirror is appropriate for application of transportation due to its fast switching response.

A controllable transparent device using an inorganic glass gel-dispersed liquid crystal (GDLC) was fabricated using the sol-gel method to overcome the limitations of conventional polymer-dispersed liquid crystals, such as haziness and yellowing. In this study, silica gel and titanium dioxide acted as a matrix holding the liquid crystal droplets, and the optical properties of the proposed GDLC were then studied in a silica solution by mixing tetra ethyl ortho-silicate, methyltriethoxysilane, isopropyl alcohol, and nitric acid in an aqueous solution. A titanium solution with titanium isopropoxide and acetylacetone was also mixed with the silica solution, with the further addition of a nematic liquid crystal. A parameter study was carried out by varying the concentration to obtain the best sample, with fast response times of ~0.5 and 3 ms, respectively for the on and off processes, high contrast, and low haziness when compared with previously reported results. The GDLC samples exhibited low scattering, a clear colorless state, and a low driving voltage, which are all very important advantages for applications. For demonstration, our glass-based smart window was also applied as a rear-view mirror in a vehicle for anti-dazzling purposes at night, which has not been reported by others.