Modification of a-C:H film surface by atmospheric pressure plasma jet for liquid crystal alignment

The present research work is devoted to developing methods of manufacturing liquid crystal (LC) cells. Ultrathin hydrogenated amorphous carbon (a-C:H) films are deposited on glass substrates by the plasma enhanced chemical vapor deposition method. To impart alignment properties these substrates are exposed under the atmospheric pressure plasma jet (APPJ) scanning system. Raman spectroscopy is used to describe the structural change in the a-C:H film. A polarizing optical microscope is used to describe the properties of the composed LC cells. We found that using a-C:H film as an alignment layer shows the same result as when conventional polyimide film is used. Moreover, the treatment of the a-C:H or polyimide film surfaces by the APPJ system results in good LC molecule alignment on the surface of these films.