Photo-induced liquid crystal alignment with discotic films

Abstract

Photo-induced liquid crystal alignment using cross-linked discotic compounds was demonstrated. These discotic compounds exhibit good solubility in common organic solvents, 60 degreesC processing temperature and excellent thermal stability. A linearly polarized long wave ultraviolet light (lambda = 350 nm) was used to initiate the cross-linking process which, in turn, induces liquid crystal alignment on the discotic film surface. The polarity of discotic compounds plays an important role in affecting the pretilt angle of the liquid crystal alignment. A pretilt angle of 1 +/- 0.4 degrees was obtained using single exposure at oblique angle. Potential application of this new photo-alignment film for low temperature poly-silicon thin-film-transistor liquid crystal display is foreseeable.