Liquid Crystal Composition for Fast Response and Low Voltage
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Solution Overview
Problem
Current liquid crystal materials for TFT-LCDs face challenges in achieving fast response times, low driving voltage, and high stability under various conditions such as chemical, thermal, and electromagnetic radiation, while also requiring wide nematic phase temperature range, appropriate birefringence anisotropy, high resistivity, and good anti-ultraviolet performance.
Innovation Solution
A liquid crystal composition comprising specific compounds with tailored molecular structures, including formula I, II-A, and other additives, which provide moderate dielectric and optical anisotropy, low rotary viscosity, and high clearing points, optimized for blending to achieve fast response and stability, without CN structures or pyridine rings that could degrade electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the rotary viscosity γ1 is reduced to achieve fast response, then the response time is improved, but the driving voltage may need to be increased to maintain adequate torque
Solution Approach 1:
The patent modifies molecular parameters by introducing specific substituent groups (fluoro, alkoxy, alkyl) at defined positions on the terminal rings of the liquid crystal molecules. This changes the intermolecular interaction parameters to achieve the desired balance between viscosity and dielectric anisotropy
Solution Approach 2:
The patent employs composite liquid crystal compositions blending multiple compounds with different molecular structures (cyclic and non-cyclic compounds with specific formulas). The synergistic effect of the blend achieves fast response while maintaining moderate dielectric anisotropy and low viscosity
2Use of energy by moving object
If the driving voltage is reduced to lower power consumption, then energy consumption is improved, but the response speed may be reduced
Solution Approach 1:
The patent optimizes molecular parameters to achieve moderate dielectric anisotropy (Δε = 3-7), which allows for lower driving voltages while maintaining adequate response performance. This is accomplished through specific substituent patterns that balance polar and non-polar interactions
3Temperature
If the nematic phase temperature range is widened, then the operational temperature range is improved, but the viscosity and response characteristics may be affected
Solution Approach 1:
The patent introduces different types of terminal groups (cyclic and non-cyclic) with specific local structures that provide low-temperature flexibility while maintaining high-temperature stability. The cyclic compounds provide rigid cores for thermal stability, while non-cyclic compounds with flexible chains improve low-temperature fluidity
Solution Approach 2:
The patent creates composite blends of cyclic and non-cyclic liquid crystal compounds with specific molecular formulas. This combination allows the mixture to maintain wide nematic phase temperature range while preserving fast response characteristics through optimized molecular interactions
Data Source
AI summary
A liquid crystal composition having one or more compounds shown as formula I and one or more compounds shown as formula II, and the liquid crystal composition comprising a compound shown as formula II-A:wherein substituents are all defined. The composition has a low viscosity γ1, a moderate dielectric anisotropy Δε and a moderate optical anisotropy Δn, and can achieve fast response of a liquid crystal display.