Tunable colors of chiral liquid crystal displays

We report a method of the color variation in the reflective CLC displays depending on thermo-dynamically and the electric field switching. The reflective wavelength can be thermodynamically switched to reflect green from a cell initially reflecting a red color. Afterwards, the reflective wavelength can be electrically switched to reflect blue color. It is found that continuous decrease of the pitch is mainly originated from the dopant solubility below the critical temperature and stepwise decrease of the pitch is dominantly affected by the thermodynamic property above the critical temperature. The blue color change is a result of the compression to the helical pitches in planar layers in response to the applied voltage.