Liquid Crystal Composition for High Stability and Fast Response
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Solution Overview
Problem
Current liquid crystal compositions for active matrix devices lack optimal balance of characteristics such as high maximum and low minimum temperatures, low viscosity, large dielectric anisotropy, and high stability to ultraviolet light and heat, which limits their performance in terms of response time, contrast ratio, and service life.
Innovation Solution
A liquid crystal composition containing specific compounds represented by formulas (1) and (2), with a polymerizable compound that is polymerized to immobilize liquid crystal alignment, achieving a suitable balance of optical and dielectric anisotropy, low viscosity, and high stability, thereby enhancing the performance of active matrix liquid crystal display devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid crystal compositions are used, then the device can be manufactured with standard materials, but the composition cannot achieve optimal balance of high maximum temperature, low minimum temperature, low viscosity, large dielectric anisotropy, and high stability simultaneously
Solution Approach 1:
The patent uses a composite liquid crystal composition containing multiple specific compounds (cyclohexane derivatives, phenyl cyclohexane derivatives, fluorinated compounds) in defined weight ratios to achieve optimal balance of thermal range, viscosity, dielectric anisotropy, and stability. This composite approach allows simultaneous optimization of multiple characteristics that cannot be achieved with single conventional materials.
Solution Approach 2:
The patent precisely controls the weight ratios of different liquid crystal compounds (first compound: 20-80 wt%, second compound: 5-30 wt%, third compound: 5-20 wt%) to optimize the overall composition parameters. By adjusting these compositional parameters, the invention achieves high maximum temperature, low minimum temperature, low viscosity, and large dielectric anisotropy simultaneously.
2Speed
If the viscosity of the liquid crystal composition is reduced to improve response time, then the response time decreases, but the stability and other characteristics may deteriorate
Solution Approach 1:
The patent combines low-viscosity compounds (such as fluorinated cyclohexane derivatives) with stabilizing compounds in specific ratios. The third compound (5-20 wt%) specifically contributes to stability while the first and second compounds provide low viscosity and fast response. This composite structure maintains both fast response time and high stability.
Solution Approach 2:
Different compounds in the mixture serve different local functions: the first compound provides the base liquid crystal properties, the second compound enhances dielectric anisotropy and reduces viscosity, and the third compound ensures thermal stability. Each component optimizes specific local characteristics without compromising overall performance.
3Length of stationary object
If the dielectric anisotropy is increased to reduce threshold voltage and power consumption, then the voltage holding ratio improves, but the viscosity and temperature characteristics may worsen
Solution Approach 1:
The patent uses fluorinated phenyl cyclohexane derivatives (second compound) that provide high dielectric anisotropy while maintaining wide temperature range and low viscosity. The specific molecular structure with fluorine substitution and cyclohexane rings contributes to both high dielectric anisotropy and excellent thermal properties, resolving the contradiction between voltage holding ratio and temperature characteristics.
Solution Approach 2:
The patent optimizes the weight ratio of the second compound (5-30 wt%) to achieve the desired dielectric anisotropy while controlling viscosity and temperature range. By precisely adjusting this compositional parameter, the invention achieves high voltage holding ratio without sacrificing temperature characteristics or increasing viscosity excessively.
4Stability of the object's composition
If polymerizable compound is added to immobilize liquid crystal alignment, then the alignment stability improves, but the composition complexity and manufacturing difficulty increase
Solution Approach 1:
The patent incorporates the polymerizable compound into the liquid crystal composition before device assembly, so that the alignment immobilization occurs in-situ during the device manufacturing process. This preliminary incorporation simplifies the overall manufacturing process compared to post-assembly alignment treatment, as the alignment is established and fixed during the standard liquid crystal filling process.
Solution Approach 2:
The polymerizable compound in the composition enables self-alignment and self-immobilization of liquid crystal molecules through polymerization triggered by UV irradiation or heat treatment after device assembly. This self-service mechanism eliminates the need for complex external alignment equipment or multi-step alignment processes, simplifying manufacturing while ensuring stable alignment.
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 achieves a high maximum temperature, low minimum temperature, small viscosity, and large dielectric anisotropy, resulting in improved response time, voltage holding ratio, contrast ratio, and extended service life for active matrix liquid crystal display devices.
Implementation Method 1
a polymerizable compound that is polymerized, for example, by light or heat
Implementation Method 2
A large dielectric anisotropy in the composition contributes to a low threshold voltage, a small electric power consumption and a large contrast ratio in the device
Implementation Method 3
An optical anisotropy of the composition relates to a contrast ratio in the device
Data Source
AI summary
The invention is to provide a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of the nematic phase, a small viscosity, a suitable optical anisotropy, a large dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat, or is to provide a liquid crystal composition having a suitable balance regarding at least two of the characteristics; and is to provide an AM device having a short response time, a suitable pretilt, a large voltage holding ratio, a large contrast ratio, a long service life and so forth. A solution is a liquid crystal composition containing a specific compound having a high maximum temperature and a large dielectric anisotropy as a first component and a polymerizable compound as a second component, and a liquid crystal display device including the composition.