CF2O-Tolan Liquid Crystal Compound for Display Performance
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Solution Overview
Problem
Current liquid crystal compounds do not adequately meet the requirements for high stability to heat and light, high clearing point, low minimum temperature of the liquid crystal phase, small viscosity, large optical anisotropy, large dielectric anisotropy, suitable elastic constant, and compatibility with other liquid crystal compounds, which are necessary for improving the performance of liquid crystal display devices.
Innovation Solution
A liquid crystal compound represented by a specific formula with a CF2O bonding group and a tolan skeleton, which provides a balance of physical properties such as high optical anisotropy and dielectric anisotropy, is developed. This compound is incorporated into a liquid crystal composition and used in liquid crystal display devices to enhance their performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid crystal compounds are used, then the device can be manufactured with current technology, but the compound does not provide adequate stability to heat and light, and does not achieve high clearing point, low minimum temperature, small viscosity, large optical anisotropy, large dielectric anisotropy, or excellent compatibility
Solution Approach 1:
The patent employs a composite molecular structure combining a tolan skeleton (for structural stability and high clearing point) with CF2O bonding groups (for enhanced dielectric anisotropy and thermal stability). This composite approach allows simultaneous achievement of multiple desired properties that cannot be obtained with conventional single-structure liquid crystal compounds.
Solution Approach 2:
The invention systematically varies molecular parameters including the introduction of CF2O groups, modification of terminal groups (R1, R2), and adjustment of aromatic ring structures to optimize the balance between clearing point, viscosity, dielectric anisotropy, and thermal stability. By changing these molecular parameters, the compound achieves a superior balance of physical properties.
2Weight of stationary object
If the clearing point is increased to extend the temperature range, then the high-temperature performance is improved, but the minimum temperature of the liquid crystal phase may increase, potentially reducing the low-temperature operability
Solution Approach 1:
The patent introduces specific local structural features (CF2O bonding groups at particular positions in the molecule) that selectively influence the clearing point without significantly affecting the minimum temperature. This local modification allows independent optimization of the upper temperature limit while maintaining low-temperature fluidity.
Solution Approach 2:
By adjusting molecular parameters such as the type of terminal groups (R1, R2), the number and position of CF2O groups, and the aromatic ring substitutions, the patent independently controls the clearing point and minimum temperature, achieving a wide liquid crystal phase temperature range.
3Speed
If the viscosity is decreased to shorten the response time, then the response speed is improved, but the optical anisotropy and dielectric anisotropy may be reduced, affecting the contrast and threshold voltage
Solution Approach 1:
The composite molecular structure with tolan skeleton and CF2O groups creates a unique balance where the rigid core maintains high optical anisotropy while the fluorinated bonding groups reduce intermolecular interactions, lowering viscosity. This composite structure achieves both fast response and high contrast.
Solution Approach 2:
The patent optimizes molecular parameters including the introduction of CF2O groups (which reduce viscosity through weak intermolecular forces) while maintaining the conjugated tolan structure (which preserves high optical anisotropy). This parameter optimization achieves the desired balance between response speed and optical performance.
4Use of energy by moving object
If the dielectric anisotropy is increased to reduce the threshold voltage, then the power consumption is reduced, but the optical anisotropy may be compromised, affecting the contrast ratio
Solution Approach 1:
The patent's composite structure combines the conjugated tolan skeleton (providing high optical anisotropy) with CF2O bonding groups (providing high dielectric anisotropy through fluorine atoms' high electronegativity). This composite design achieves simultaneous enhancement of both optical and dielectric properties, enabling low threshold voltage and high contrast ratio.
Data Source
AI summary
To show a liquid crystal compound satisfying at least one of physical properties such as high chemical stability, a high clearing point, a low minimum temperature of a liquid crystal phase, low viscosity, large optical anisotropy, large dielectric anisotropy, a suitable elastic constant and excellent compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition.A compound is represented by formula (1).