Fluorinated Liquid Crystal Compounds for Blue Phase Displays
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Solution Overview
Problem
Existing liquid-crystalline media for blue phase displays face challenges with high switching voltages, low stability, and high hysteresis, requiring materials with high dielectric and optical anisotropy, and low rotational viscosity, while also needing to avoid ester and nitrile compounds for improved electrical resistance and long-term stability.
Innovation Solution
Development of liquid-crystalline compounds with a specific O-heterocyclic ring and three partially fluorinated benzene rings, connected by a -CF2O bridge, which exhibit high dielectric anisotropy, optical anisotropy, and low rotational viscosity, suitable for use in blue phase displays, and can be synthesized through specific reaction pathways involving aldehydes, alcohols, and Lewis acids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid-crystalline media are used for blue phase displays, then the displays can operate, but they require high switching voltages and exhibit low stability with high hysteresis
Solution Approach 1:
The patent changes the molecular structure parameters of liquid-crystalline compounds by introducing specific fluorinated benzene rings and O-heterocyclic structures, which fundamentally alters the dielectric and optical properties of the medium, enabling low-voltage operation with high stability
Solution Approach 2:
The invention creates composite liquid-crystalline media by combining multiple compounds with specific molecular structures (formula I and related compounds), achieving synergistic effects that simultaneously improve stability and reduce switching voltage requirements
2Reliability
If ester and nitrile compounds are included in liquid-crystalline media, then the media can be formulated, but the electrical resistance decreases and long-term stability is reduced
Solution Approach 1:
The patent removes ester and nitrile compounds from the liquid-crystalline media composition, eliminating the harmful components that cause low electrical resistance and poor stability, while maintaining the necessary liquid crystalline properties through alternative molecular structures
Solution Approach 2:
The invention replaces unstable ester and nitrile compounds with more stable fluorinated aromatic compounds, sacrificing some formulation flexibility to gain significant improvements in electrical resistance and long-term operational stability
3Speed
If liquid-crystalline compounds with high dielectric anisotropy are used, then fast switching is achieved, but the clearing point increases
Solution Approach 1:
The patent introduces localized fluorinated groups and O-heterocyclic structures at specific positions in the molecular structure, creating local regions with high polarizability that enhance dielectric anisotropy without uniformly increasing the overall clearing point of the material
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These compounds enable fast switching with low voltages, high clearing points, and improved stability, making them suitable for polymer-stabilized blue phase displays with reduced memory effect and enhanced solubility, while being free from ester and nitrile compounds for increased electrical resistance.
Implementation Method 1
The basis for fast switching processes in these phases is the so-called Kerr effect. The Kerr effect is the change in birefringence of an optically transparent and isotropic material caused by an external electric field.
Implementation Method 2
the change in birefringence is represented by the following equation: Δn induced = K·E²·λ
Data Source
AI summary
The present invention relates to liquid-crystalline compounds having an O-heterocyclic ring, three partly fluorinated benzene rings and a -CF2O- bridge between the rings. The invention also relates to liquid-crystalline media produced therewith and to liquid-crystal display devices (LC displays) that comprise these media.