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Freedericksz instability for the twisted nematic device: A three-dimensional analysis
G I Sfyris1, K Danas1, G Wen1
1LMS, Ecole Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France.
Physical Review. E
|August 31, 2016
Summary
The Freedericksz transition in twisted nematic devices (TNDs) can be global or local, depending on the twist angle. Increasing the twist angle can lower the critical electric field, aiding liquid crystal material selection for displays.
Area of Science:
- Physics
- Materials Science
- Engineering
Background:
- The Freedericksz transition is crucial for liquid crystal display (LCD) operation.
- Twisted nematic devices (TNDs) are widely used in monitors.
- Understanding transition behavior under electric fields is essential for device optimization.
Purpose of the Study:
- To conduct a fully three-dimensional analysis of the Freedericksz transition in TNDs.
- To investigate the influence of twist angle and electric fields on transition modes.
- To determine conditions for global versus local (periodic) Freedericksz transitions.
Main Methods:
- Utilized a coupled electromechanical variational formulation.
- Treated the transition as a bifurcation instability induced by an electric field.
- Analyzed a finite liquid crystal layer with specific boundary conditions and twist.
Main Results:
- Identified that global Freedericksz transition modes are common at low twist angles.
- Observed local (periodic) transition modes at large twist angles.
- Found that increasing twist angle can reduce the critical electric field in some TNDs.
Conclusions:
- The study provides a comprehensive 3D analysis of Freedericksz transitions in TNDs.
- Results indicate a transition from global to local modes with increasing twist angle.
- Findings can guide the selection of liquid crystal materials for improved display performance.
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