Stable photopatterned cholesteric layers made by photoisomerization and subsequent photopolymerization for use as color filters in liquid-crystal displays

New thermally and mechanically very stable cholesteric layers with patterned reflection colors were described. As such, the layers were made by coating a monomeric cholesteric mixture on a substate followed by a sequence of photochemical processes, namely photoisomerization and photopolymerization. In order to separate both processes, the isomerization was performed in air to avoid polymerization, and the photopolymerization was performed in nitrogen with longer-wavelength UV irradiation.