π bistable twisted nematic device sustained by polymer walls

A bistable twisted nematic (BTN) liquid crystal cell can generally be fabricated by adding a chrial additive to the liquid crystal materials. In this paper, we propose a novel BTN liquid crystal mode sustained by polymer walls without any chiral dopant. With parallel rubbed substrates, the pi twist state can be stabilized by utilizing the fluorinated-polymer wall. Therefore, bistable characteristics can be achieved without any chiral dopant. We demonstrate switching process between two stable states which show permanent memory time.