Cholesteric Liquid Crystalline Polyether with Broad Tunable Circularly Polarized Luminescence

Area of Science:

• Materials Science
• Optics
• Polymer Chemistry

Background:

• Cholesteric liquid crystalline (CLC) materials are known for their unique optical properties, including selective reflection of circularly polarized light.
• Achieving strong and tunable circularly polarized luminescence (CPL) in CLC systems remains a challenge for advanced photonic applications.

Purpose of the Study:

• To develop novel polyether-based CLC copolymers capable of strong CPL with high purity and broad tunability.
• To investigate the relationship between copolymer composition, temperature, and the resulting CLC phase behavior and optical properties.
• To explore the potential of these materials in flexible CLC elastomers and their application in displays and photonics.

Main Methods:

• Synthesis of polyether-based CLC copolymers incorporating chiral cholesteryl, nematic mesogens, and cross-linkable moieties.
• Construction of phase boundary diagrams to determine CLC phase windows.
• Tuning of reflection colors across the infrared and visible regions via composition and temperature.
• Photo-cross-linking to create flexible CLC elastomers.
• Incorporation of achiral dyes to generate CPL and measurement of dissymmetry factors (g_lum).

Main Results:

• Achieved strong CPL with high purity and broad tunability in the new CLC copolymers.
• Established a wide composition and temperature window for the CLC phase, extending to room temperature.
• Demonstrated continuous tuning of reflection colors across IR and visible regions, fixable in elastomers.
• Generated strong CPL with distinct handedness and high dissymmetry factors by introducing achiral dyes.
• Obtained left-handed full-color CPL via selective scattering and right-handed CPL (g_lum up to -1.05) via selective reflection.

Conclusions:

• The developed polyether-based CLC copolymers are promising active materials for generating strong, tunable CPL.
• The ability to tune and fix optical properties in flexible elastomers opens avenues for novel photonic devices.
• These materials hold significant potential for applications in next-generation liquid crystal displays and advanced photonics.