Model for ion transport in AM-LCD´s

Leakage current measurements on LC (liquid crystal) cells are useful for examining the ionic presence and transport in the liquid crystal layer. A model is presented that can explain this leakage current behavior. In this model the ions are formed by the ionization of a number of neutral impurities. The ionization gives rise to positive and negative ions of which one type is considered much more mobile than the other. The ions can be trapped at the interfaces with the alignment layers. These assumptions allow a fit of the simulations and experiments. In this way the measurements can also be a powerful tool to understand and evaluate the influence of the different materials used for the production of displays, especially the alignment films and the liquid crystals themselves, or to understand the influence of high temperatures or ultraviolet illumination.<>