Reversible-Photon-Mode Full-Color Display by Means of Photochemical Modulation of a Helically Cholesteric Structure

Photochemical modulation of the selective reflection of cholesteric liquid crystals over a wide range of the visible spectrum is achieved using the E–Z photoisomerization of compounds that have multiple chiral sites and azobenzene groups in the same molecule. The aspect ratio of the photoisomerizable compounds is important for changing the twisting ability of the azobenzene compounds. Blue, green, and red color patterning was accomplished with a resolution of 10–70 μm (see Figure).