Balance working temperature and viewing angle properties in polymer dispersed liquid crystal film via SiO2

The application of polymer dispersed liquid crystal (PDLC) film has been significantly hindered due to its unsatisfactory contrast ratio ( CR ) in high-temperature environments, delayed response speed in low-temperature conditions, and suboptimal off-axis viewing angles. To address these issues, nano-particle SiO 2 with a similar refractive index to polymer was introduced into the film, and then the electro-optical properties and viewing angle characteristics of PDLC films with different contents of SiO 2 at 100 °C and −30 °C were analyzed. When the doping amount of SiO 2 is 1.5 wt% of the polymer component, the contrast ratio of PDLC films at 100 °C is increased to 16, which is 60 % higher than that of undoped SiO 2 films. At −30 °C, the saturation voltage is 59 V (2.95 V/μm), and the rise time and decay time are 0.35 s and 2.5 s, respectively, slightly higher than the film without doping SiO 2 . The film also maintained a good viewing angle, with H on  < 15 % at 45° and T on  > 60 % at 60°. Balancing the film’s viewing angle and working temperature is anticipated to enhance its applicability for outdoor smart windows.