Photoalignment of Ferroelectric Liquid Crystals by Azodye Layers

The photoinduced alignment of ferroelectric liquid crystals (FLCs) onto photochemically stable azo-dye films was studied. The alignment quality of FLC display cells depends mainly on the difference between the FLC surface energy and the aligning substrates surface energy; however, the structure and thickness of FLC layers are also important. The effect of the thickness of photoaligning azodye layer on the alignment quality and multiplex operation of passively addressed FLC display cells has been investigated. An optimal (about 3–5 nm) azo-dye layer thickness that provides both the highest multiplex operation steadiness and the best contrast ratio of the FLC display cells was found. The photoaligned FLC display cells showed the contrast ratio CR>500:1 at the wavelength λ=0.63 µm both in surface stabilized and deformed helix FLC electrooptical modes.