Relationship between Dipole Moment of Organic Compound Impurity in Liquid Crystal Field and Leakage Current of Liquid Crystal Cell

The degradation of the reliability of liquid crystal display (LCD) is dependent on ions in the liquid crystal (LC) cell. However, we found that the nonionic organic compounds added into the LC material also decreased the reliability of LCD because of the leakage current. The conductivity and the dielectric constant of the LC cells containing an LC mixture (ZLI-2293) with or without the nonionic organic compounds were examined by the AC impedance method. The leakage current, as well as the conductivity, was found to be related to the dipole moment of the compound. Therefore, if the dipole moment of the compound is larger than 4 D, the current will tend to leak in the LC cell.