Broad temperature range ferrielectric liquid crystal as a highly sensitive quadratic electro-optical material

Area of Science:

• Materials Science
• Condensed Matter Physics
• Crystallography

Background:

• Chiral smectic liquid crystals (CSLCs) are known for their unique electro-optical properties.
• Ferrielectric phases in CSLCs are characterized by a helix structure.
• Achieving a wide temperature range for specific phases is crucial for practical applications.

Purpose of the Study:

• To develop a chiral smectic liquid crystal exhibiting a ferrielectric phase with a subwavelength helix pitch.
• To achieve this phase over an extended temperature range, including room temperatures.
• To characterize the electro-optical properties of the developed material.

Main Methods:

• Synthesis and characterization of a novel chiral smectic liquid crystal material.
• Differential scanning calorimetry and polarized optical microscopy to determine phase behavior and temperature ranges.
• Electro-optical measurements to assess the quadratic electro-optical effect and response times.

Main Results:

• A ferrielectric phase with a helix pitch (p0) < 125 nm was achieved over a temperature range of at least -3°C to +36°C.
• This wide temperature range for a subwavelength helix pitch ferrielectric phase is reported for the first time.
• A high Kerr coefficient (almost 200 nm/V²) was observed, significantly exceeding that of blue and smectic C* phases.
• Electro-optical response times were found to be below 300 μs at room temperature.

Conclusions:

• The developed chiral smectic liquid crystal demonstrates a practical ferrielectric phase with a subwavelength helix pitch over a broad temperature range.
• The material exhibits a strong quadratic electro-optical effect and high sensitivity to electric fields.
• These findings pave the way for the practical application of ferrielectric liquid crystals in electro-optical devices.