Surface anchoring energy modulation in liquid crystal cells with mixed conductor boundary layers

This work concerns the experimental analysis of the influence of the surface charge on the anchoring energy of a nematic liquid crystal ~NLC!. The study has been carried out on sandwich like cells in which the semitransparent indium tin oxide electrodes were covered by a sputtered tungsten trioxide film to supply an extra amount of surface charge. We found that the huge amount of tungsten-oxide protons injected at the oxide-NLC interface play a key role in weakening the surface anchoring energy. To estimate the surface anchoring energy during a bias-controlled injection process, a photopolarimetric technique has been used. The result highlights the importance of the polarized surface on the anchoring breaking mechanism.