Electrically induced bleaching of ion-dye doped nematic liquid crystal

We report on electrically controlled chromatic effect in liquid crystals (LC) doped with ion-dye astrofloxine molecules. We investigated the dependencies of visible spectra of the system on concentration, electric field and time of applying of dc-field. We also measured conductivity of the system on the cell age. Obtained results allowed us to associate the photochromic effect with neutralizing of the ion-dye molecules on the aligning surfaces. The application of the dc-field causes spatial separation of the charges in the cell and their adsorption on the aligning surfaces. The adsorption results in a sharp decrease of the electron conjugation in the dye molecules and in turn, to the bleaching effect.