Bistable normally bright smart window with planarly aligned cholesteric liquid crystal

A bistable smart window is demonstrated using a planarly aligned helix (PAH) texture of the cholesteric liquid crystal (CLC) achieved using 10 wt.% CB15 chiral agent and HNG-7156-100 negative dielectric anisotropy LC with homeotropic alignment layer. This window can be either transparent or opaque without continuous applied voltage. By applying a low-frequency (100 Hz) voltage pulse, the window switches from transparent to opaque due to the dielectric response of the LC molecules trying to unwind the helix assisted by ions movement, known as the EHDI effect, thus forming the focal conic state which is opaque. A high-frequency (2 kHz) voltage pulse then returns it to a transparent state. This bistability makes an energy-saving, switchable privacy controlled window.