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Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Photoalignment of liquid crystals by liquid crystals
Reznikov1, Ostroverkhova, Singer
1Institute of Physics of National Academy of Science, Prospect Nauki 46, Kyiv 252022, Ukraine.
Physical Review Letters
|October 4, 2000
Summary
This study demonstrates light-induced alignment of 4,4(
Area of Science:
- Materials Science
- Optoelectronics
- Surface Chemistry
Background:
- Nematic liquid crystals (LCs) are crucial in display technologies.
- Controlling LC alignment on surfaces is vital for device performance.
- Existing alignment methods often involve mechanical rubbing or complex surface treatments.
Purpose of the Study:
- To investigate light-induced alignment of 5CB liquid crystal on fused quartz.
- To explore the effect of polarized UV light on LC alignment.
- To quantify the anchoring energy and characterize the alignment.
Main Methods:
- Adsorption of 4,4(')-n-pentylcyanobiphenyl (5CB) on fused quartz.
- Irradiation with polarized ultraviolet light.
- Measurement of anchoring energy, phase retardation, and pretilt angles.
- Second harmonic generation (SHG) for adsorbed layer analysis.
Main Results:
- Homogeneous alignment of 5CB in a liquid crystal cell was achieved.
- Alignment easy axis was perpendicular to the UV polarization direction.
- Anchoring energy increased with illumination, reaching 10(-4) erg/cm^2.
- SHG indicated near-normal alignment of the adsorbed layer.
Conclusions:
- Light-induced rearrangement or phototransformation of the adsorbed layer is proposed as the mechanism.
- This offers a novel, non-contact method for LC alignment.
- Potential applications in advanced optical and display devices.
