Fast copolymer network liquid crystals for tunable birefringence colors

Area of Science:

• Materials Science
• Liquid Crystal Displays
• Polymer Chemistry

Background:

• Liquid crystals (LCs) are widely used in display technologies due to their tunable optical properties.
• Developing novel LC composites with enhanced electro-optic performance and color tunability is an ongoing area of research.
• Controlling defects and achieving specific optical characteristics in polymer LC composites can be challenging.

Purpose of the Study:

• To investigate a copolymer network liquid crystal (LC) as a fast-switching, tunable color filter.
• To explore the electro-optic properties and color generation mechanisms in a novel LC composite.
• To assess the potential of this material for non-display applications.

Main Methods:

• In situ generation of a copolymer network LC within a conventional LC test cell with parallel aligned glass plates.
• Investigation using polarized light and polarization filters to convert optical phase retardance to birefringence colors.
• Recording transmittance spectra, converting to CIE 1931 color coordinates, and measuring electro-optic switching times.

Main Results:

• Achieved fast electro-optic switching times of less than 5 ms, which is impressive for tunable birefringence colors.
• Observed a blueshift in transmittance spectra peaks with increasing addressing voltages.
• Successfully avoided typical pastel colors and achieved colors with reasonable distance to the white point in a 9 μm cell gap, preventing defects.

Conclusions:

• The copolymer network LC functions as a fast-switching, tunable color filter with potential for non-display applications.
• The material's ability to avoid pastel colors and achieve rapid switching opens new avenues for LC composite utilization.
• Controlling cell gap below interdefect distances is crucial for defect-free polymer LC composites.