Temperature dependence of electro-optical characteristics of polymer dispersed liquid crystal films

Abstract

Polymer dispersed liquid crystal (PDLC) films consist of microdroplets of a liquid crystal dispersed in a polymer matrix. Their applications are based on the electrically controllable light scattering properties of the liquid crystal droplets. The effects of temperature on the electro-optical properties of PDLC films have been rarely investigated. In this work, we studied the light transmission on varying the temperature and frequency. It was observed that the transmission at a fixed voltage decreased with increasing temperature above 43°C, independent of frequency. We examined possible origins of this unusual dependence of the transmission on the temperature. It was concluded that conductivity effects due to free ions newly created at high temperatures could be responsible for the unusual behaviour observed.