Liquid Crystal Composition for Fast Response and Low Threshold Voltage
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Solution Overview
Problem
Conventional liquid crystal compositions for active matrix devices lack optimal balance of characteristics such as wide temperature range, short response time, high contrast ratio, low threshold voltage, and long service life, particularly in terms of viscosity, dielectric anisotropy, and stability to ultraviolet light and heat.
Innovation Solution
A liquid crystal composition comprising three or four components, specifically selected compounds that balance dielectric anisotropy, viscosity, and thermal stability, including compounds represented by certain formulas, to achieve a nematic phase with optimal optical anisotropy, low viscosity, and high specific resistance, ensuring fast response and long service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a liquid crystal composition has large dielectric anisotropy, then threshold voltage is low and contrast ratio is large, but viscosity becomes large which increases response time
Solution Approach 1:
The patent changes the molecular structure parameters of liquid crystal compounds by introducing specific functional groups (cyano groups at positions 2 and 5, fluorine atoms at positions 3 and 6) to achieve optimal balance between dielectric anisotropy and viscosity. This structural parameter modification allows the composition to maintain large dielectric anisotropy for low threshold voltage while controlling viscosity for fast response time.
Solution Approach 2:
The patent uses a composite liquid crystal composition comprising multiple compounds (compounds of formula (1) and compounds of formula (2)) in specific ratios. This composite approach allows the composition to inherit favorable properties from different components: compound (1) provides high dielectric anisotropy while compound (2) controls viscosity, achieving an optimal balance for both low threshold voltage and fast response time.
2Speed
If a liquid crystal composition has small viscosity, then response time is short, but dielectric anisotropy becomes small which increases threshold voltage
Solution Approach 1:
The patent modifies molecular parameters by introducing rigid aromatic rings and specific functional groups to maintain adequate dielectric anisotropy while using fluorine substitution and controlled molecular weight to reduce viscosity. This parameter optimization achieves both short response time and low threshold voltage.
Solution Approach 2:
The patent combines liquid crystal compounds with different molecular structures in a composite composition. Compound (1) with cyano groups provides high dielectric anisotropy, while compound (2) with fluorine atoms provides low viscosity. The composite composition achieves synergistic effects where the combination of components delivers both fast response time and low threshold voltage simultaneously.
3Reliability
If a liquid crystal composition has high stability to ultraviolet light and heat, then service life is long, but other performance characteristics may be compromised
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating compounds with specific molecular structures known for high thermal and photostability. The use of fluorine-substituted aromatic compounds and compounds with rigid molecular frameworks provides enhanced stability to ultraviolet light and heat while maintaining excellent performance characteristics including fast response time and low threshold voltage.
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
The composition provides a liquid crystal display device with a wide temperature range, short response time, high contrast ratio, low threshold voltage, and extended service life, while maintaining stability to ultraviolet light and heat, thereby enhancing the performance and reliability of active matrix devices.
Implementation Method 1
The composition has a nematic phase and a positive dielectric anisotropy
Implementation Method 2
The optical anisotropy of the composition relates to the contrast ratio of the device
Implementation Method 3
A large dielectric anisotropy of the composition contributes to a low threshold voltage, a small electric power consumption and a large contrast ratio
Data Source
AI summary
A liquid crystal composition having a nematic phase that includes three components, wherein the first component is at least one compound selected from the group of compounds represented by formula (1), the second component is at least one compound selected from the group of compounds represented by formulas (2-1) to (2-3), and the third component is at least one compound selected from the group of compounds represented by formula (3): wherein, for example, R1, R2, R3, R4, R5, R6, R7 and R8 are alkyl having 1 to 12 carbons; Y1 is fluorine, -OCF3 or -OCHF2; and X1, X2, X3, X4, X5 and X6 are each independently hydrogen or fluorine, provided that at least one of X4, X5 and X6 is fluorine.