TIME-DEPENDENCE OF IMPEDANCE CHARACTERISTIC OF NEMATIC LIQUID-CRYSTALCELL

The frequency dependence of the impedance of a liquid crystal cell was measured for 4-n-pentyl-4'-cyanobiphenyl. The resistivity of a liquid crystal layer decreases due to two relaxation processes. The relaxati on time for the slow process is about 4000 h, and that for the fast pr ocess is of the order of 100 h. This implies that the carrier ion conc entration increases over a long period of time. A surface double layer was detected at the polyimide in the low frequency region, the thickn ess of which tends to decrease with time.