Anchoring strength of indium tin oxide electrode used as liquid crystal alignment layer

To reduce the manufacturing cost of liquid crystal (LC) panels, we examine the potential of an ion-beam-treated indium tin oxide (ITO) film as an LC alignment layer as well as a transparent electrode. In this study, thus, an ITO film in an LC panel is developed to serve as an LC alignment layer as well as an electrode. To determine if they can be utilized for liquid crystal display (LCD) applications, we investigate the anchoring strength of ITO alignment layers according to ion beam conditions through the roll pattern in electroconvection of LCs. In the optimized ion beam condition of our experiment, the azimuthal surface anchoring strength of the ITO alignment layer is approximately 3.1 × 10−6 N/m, which corresponds to that of polyvinyl alcohol (PVA) and is ten times higher than that of rubbed ITO alignment layers. To further enhance the anchoring strength of the ITO film by the synergistic effect of alignment methods (rubbing + ion beam treatment), we perform ion beam treatment after rubbing on the ITO film, after which the azimuthal surface anchoring strength of the ITO alignment layer is approximately 1.7 × 10−5 N/m, which is four times higher than that of rubbed PVA, thus achieving an appropriate value for LCD applications. As a result of the electro-optical characteristics of twisted nematic LC cells with rubbed and ion-beam-treated ITO alignment layers, we obtained good dark and bright states as verified by the voltage vs. transmittance curves.