Reduction of the Residual DC in the Photoaligned Twisted Nematic Liquid Crystal Display Using Polymerized Reactive Mesogen

A residual direct current (DC) voltage property in the twisted nematic liquid crystal display (TN-LCD) using photoaligned polyimide is studied by the capacitance–voltage hysteresis method. A residual DC is greatly reduced in the photoaligned cell with an additional polymerized layer on a photoaligned layer with the help of a UV-curable reactive mesogen. The surface of the photoaligned layer becomes much more polar than that of the rubbed layer, possibly leading to a larger trapping of ions on the photoaligned layer than on the rubbed polyimide layer. The polar surface can be modified with an additional proposed polymer layer and, thus, the low residual DC voltage can be achieved.