Tuning selective reflections from cholesteric liquid crystals without external stimuli

Cholesteric liquid crystals (CLCs) form self-assembled helical structures of rodlike molecules. From its periodic helical structure, the CLC exhibits a structural color by selectively reflecting circularly polarized light of the same handedness as the helix. Here, without external stimuli of electric fields, temperature, and light, we show tuning of spectral position, width, viewing angle, and diffusivity of its reflection color in a CLC by employing amorphous and nanostructured perfluoropolymer (called CYTOP) films as alignment layers. This CLC combined with perfluoropolymer films provides new possibilities in various photonic applications such as active components of photonic sensors, reflective displays, and tunable lasers.