Fast response time in liquid crystal cells doped with low concentrations of reactive mesogen via photopolymerization at low temperature

Liquid crystal (LC) cells with photopolymers usually exhibit a fast response time but inevitably present decreased optical transmittance and lower contrast ratio due to incomplete dark states. In this study, we show that this issue can be improved when photopolymerization at low temperature is considered. Comparing performance with the 4 wt% RM257-doped fringe-field switching (FFS) LC cell photopolymerized at room temperature, the 1.4 wt% RM257-doped FFS LC cell photopolymerized at low temperature (273 K) shows better contrast ratio and lower operating voltage. In addition, the electrostriction effect can be also reduced in LC cells with lower RM257-doped concentration. As a result, the 1.4 wt% RM257-doped FFS cell shows a response time as fast as that in the 4 wt% RM257-doped FFS cell. Meanwhile, the average response time for gray-to-gray switching of the optimal FFS cell is 4.9 ms.