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.