Cholesteric Liquid Crystals in Photonic Applications

Cholesteric liquid crystals (CLCs) are a subclass of liquid-crystalline materials distinguished by their self-assembled helical supramolecular organisation. The periodic variation in refractive index along the helical axis gives rise to a one-dimensional photonic band gap for circularly polarised light, enabling selective reflection across ultraviolet, visible and infrared wavelengths. Tuning of the helical pitch by chiral dopant concentration, temperature, electric field or templated polymer networks offers dynamic control of photonic properties. This versatility underpins a broad spectrum of photonic applications, from low-threshold mirror-less lasers and full-colour reflective displays to thermally tunable filters and energy-saving smart windows. Recent advances in polymer stabilisation and biomolecular assemblies have expanded the functional range of CLCs, yielding flexible, broadband infrared mirrors, biosourced structural colours and optically switchable microlasers. Integration of CLCs into scalable manufacturing processes promises to deliver compact, tunable photonic devices with low power consumption and enhanced environmental resilience, substantially impacting energy efficiency, sensing technologies and optical communication.

Research from Nature Portfolio

Electric-field-switchable broadband infrared reflectors have been realised by polymer stabilising cholesteric liquid crystal films. These devices exhibit high transparency in the visible spectrum while reflecting infrared radiation upon voltage application, enabling dynamic control of building and automotive window thermal management. Simulations indicate significant energy savings in heating and cooling, and prototypes have demonstrated concurrent electricity generation. The polymer network imparts mechanical robustness and long-term stability, paving the way for smart glazing solutions that combine thermal regulation with photovoltaic functionalities.

Cholesteric Liquid Crystals in Photonic Applications publication trend

The graph below shows the total number of articles in cholesteric liquid crystals in photonic applications across all publications each year (not limited to Nature Index journals).

Technical terms

Cholesteric liquid crystal: A liquid-crystalline phase in which rod-like molecules form layers with a twist between successive layers, creating a helical structure.

Photonic band gap: A spectral region in which light propagation is forbidden due to periodic modulation of refractive index.

Helical pitch: The distance over which the molecular orientation in a cholesteric phase rotates by 360° along the helix axis.

Polymer-stabilized cholesteric liquid crystal (PSCLC): A CLC whose helical structure is fixed within a polymer network to enhance mechanical and thermal stability.

Circularly polarised light: Light whose electric field rotates in a circular motion, matching the handedness of a cholesteric helix for selective reflection.

Bragg reflection: Constructive interference of light waves reflected from periodic structures when the Bragg condition is met.

References

1. Structural Colors from Amyloid‐Based Liquid Crystals. Advanced Materials (2023).
2. Electrically switchable polymer stabilised broadband infrared reflectors and their potential as smart windows for energy saving in buildings. Scientific Reports (2015).
3. Cholesteric liquid crystal paints: in situ photopolymerization of helicoidally stacked multilayer nanostructures for flexible broadband mirrors. NPG Asia Materials (2018).
4. Optically tunable/switchable omnidirectionally spherical microlaser based on a dye-doped cholesteric liquid crystal microdroplet with an azo-chiral dopant.. Optics Express (2013).
5. Recent Advances in Electro-Optic Response of Polymer-Stabilized Cholesteric Liquid Crystals. Materials (2023).