Optical Tuning of the Reflection of Cholesterics Doped with Azobenzene Liquid Crystals

Abstract

Mixtures of cholesteric liquid crystals doped with high clearing temperature azobenzene nematic liquid crystals 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 changes can be induced. The photoinduced states of these material systems are shown to be stable for long periods of time upon removal of the radiation source, completely reversible, and dynamically fast. These phototunable features are demonstrated using both continuous wave (CW) and nanosecond laser beams. The latter 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.

Reversible Phase Transition and Rapid Switching of Azobenzene-Doped Cholesteric Liquid Crystals with a Single Laser

“……”

Compartmentalized Janus droplets of photoresponsive cholesteric liquid crystals and poly(dimethylsiloxane)-based oligomers

“…Azobenzene dopants with the stable cis form have been used for CLCs in parallel cells with planar anchoring, where the helical twist power and the peak Bragg reflection wavelength can be altered by light irradiation. 33,34,60 There are two distinctive differences of the current study from the reports. First, for the CLC under topological constraint, a variety of metastable structures could be formed.…”

Large Thermally Irreversible Photoinduced Shift of Selective Light Reflection in Hydrazone‐Containing Cholesteric Polymer Systems

“…[71] In other words, the introduction of a non-chiral dopant leads to untwisting of the helix, whereas subsequent UV irradiation decreases the helix pitch. However, Bunning et al showed that both twisting and untwisting of the helix can occur in the second type of systems, [72] but there are no data on the composition of the used mixtures (commercial mixtures).…”

“…However, Bunning et al. showed that both twisting and untwisting of the helix can occur in the second type of systems, [72] but there are no data on the composition of the used mixtures (commercial mixtures).…”