Characterizations of photo-alignable multi-functioning polyimide material

For a potential application in thin-film-transistor liquid crystal display (TFT-LCD) manufacturing as a multi-functioning layer working as an overcoat layer and LC alignment layer simultaneously, a novel chloromethylated polyimide was synthesized. The electrical performances of liquid crystal (LC) cells with chloromethylated polyimide alignment layers were investigated. The polymer layer acted as a multifunctional layer that does role of planarization layer and photo-alignment layer with high photosensitivity and excellent thermal stability, simultaneously. The capacitance-voltage characteristics of LC cells fabricated from the photo-aligned layers were measured. The LC cells with rubbed and photo-aligned layer showed higher residual DC values and corresponding lower voltage holding ratios compared to the commercial alignment layer, probably due to the photo-induced ionic charges on the alignment layer. Mechanical rubbing of the extensively purified polymer layer did not generate much difference in residual DC when compared to commercial polyimides.