Advanced Functional Materials, Vol.17, No.11, 1735-1742, 2007
Optical tuning of the reflection of cholesterics doped with azobenzene liquid crystals
Mixtures of cholesteric liquid crystal doped with high clearing temperature azobenzene nematic liquid crystal are shown to possess large, fast, and reversible dynamic photosensitive features. Selective wavelength shifts approaching 400 nm are reported, and depending on the host cholesteric liquid crystal, both red-shifted and blue-shifted wavelength change can be induced. The photoinduced states of these material systems are showns to be stable for long periods of time upon removal of the radiation source, completely reversible, and dynamically fast. These photounable features are demonstrated using both continuous wave (CW) and nanosecond laser beams. The latters is used to change the selective reflection wavelength from blue to green with a single nanosecond pulse and the ability to write information into these films using these processes are demonstrated.