Effect of Granular Silver Films Morphology on the Molecules Orientation and Ion Contamination of Nematic Liquid Crystal

Abstract

The structure of granular silver films at the interface of liquid crystal (LC) cells and their influence on LC molecule orientation and ionic contamination are examined. Granular silver films were deposited on a glass substrate covered with an ITO electrode and a-C:H thin films. The morphology structure of the silver films was changed after their annealing at 200 °C. The silver granules became spheroidal with an average diameter of-30 nm and the channel area between them increased. The change in the structure of the Ag films led to an increase in the phase retardation and a decrease in the pretilt angle of the LC director from 51° to 7°. The density of ionic impurities in the LC cell with the annealed silver film was three times more than in the LC cell with the unannealed film. The impact of the alignment of the LC molecules at the surface of the granular silver films on the intensity of the plasmonic peak and its red shift in the absorption spectra is shown.

Nanoparticle-Enabled Ion Trapping and Ion Generation in Liquid Crystals

“…Ions in molecular liquid crystals can be generated in different ways: (i) the dissociation of neutral molecules in the bulk of liquid crystals (these dissociating species can be inherently present or added intentionally) [10-12, 14, 15]; (ii) ionic impurities as chemicals left over from the chemical synthesis [11,[16][17][18]; (iii) chemical degradation of liquid crystals [19]; (iv) ionic contaminants originated from the glue [20] and from the alignment layers [21][22][23][24][25] of the liquid crystal cell; (v)-(vii) ions generated by means of ionizing radiation [26,27], through electrochemical reactions [28][29][30], and by relatively high electric fields [31][32][33].…”