Liquid Crystal Composition for Active Matrix Display Elements
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Solution Overview
Problem
Existing liquid crystal compositions for active matrix elements face challenges in achieving a wide usable temperature range, short response time, low viscosity, low threshold voltage, and high specific resistance, which are essential for optimal display performance.
Innovation Solution
A liquid crystal composition comprising specific compounds represented by formulas (1) to (6) in defined weight percentages, carefully balanced to enhance the nematic phase temperature range, viscosity, optical anisotropy, and dielectric properties, thereby improving the overall performance of active matrix elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the viscosity of the liquid crystal composition is reduced to achieve short response time, then the response time is improved, but the voltage holding ratio deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully selecting and adjusting the molecular structures and ratios of liquid crystal compounds (cyclic carbonate compounds, cyclic carboxylate compounds, and their homologs) to achieve an optimal balance between viscosity and specific resistance. The composition specifies compounds with 1-12 carbon atoms in alkyl groups and 1-6 carbon atoms in alkoxy groups, creating a parameter-optimized mixture that simultaneously achieves low viscosity for fast response and high specific resistance for good voltage holding ratio.
Solution Approach 2:
The patent employs composite materials by formulating a multi-component liquid crystal composition containing cyclic carbonate compounds (1-30 wt%), cyclic carboxylate compounds (1-30 wt%), and their homologs in specific ratios. This composite approach combines compounds with different molecular characteristics to achieve synergistic effects: some compounds contribute to low viscosity while others maintain high specific resistance, resolving the contradiction between response time and voltage holding ratio.
2Temperature
If the maximum temperature of the nematic phase is increased to widen the usable temperature range, then the temperature range is improved, but the viscosity at high temperature increases
Solution Approach 1:
The patent applies parameter changes by selecting liquid crystal compounds with specific molecular parameters: cyclic carbonate and cyclic carboxylate compounds with alkyl groups containing 1-12 carbons and alkoxy groups with 1-6 carbons. These parameter-optimized compounds enable the composition to maintain low viscosity even at elevated temperatures while extending the maximum nematic phase temperature, thus widening the usable temperature range without sacrificing response performance.
3Illumination intensity
If the optical anisotropy is increased to improve the contrast ratio, then the contrast ratio is improved, but the threshold voltage increases
Solution Approach 1:
The patent applies parameter changes by optimizing the molecular structures of cyclic carbonate and cyclic carboxylate compounds to achieve balanced optical and electrical properties. The composition specifies compounds where the balance between optical anisotropy (Δn) and dielectric anisotropy (Δε) results in improved contrast ratio while maintaining acceptable threshold voltage levels, resolving the trade-off between these two display performance parameters.
Data Source
AI summary
A liquid crystal composition including a compound of formula (1), a compound of formula (2), a compound of formula (3), and a compound of formula (4):wherein R1 and R2 are independently an alkyl group; R3 is an alkyl or alkenyl group; Y1 is fluorine or —OCF3; Y2 is an alkyl group, an alkoxy group, fluorine, chlorine, or —OCF3; X1 is hydrogen or fluorine; A1 is 1,4-cyclohexylene or 1,4-phenylene; A2 is 1,4-cyclohexylene, 1,4-phenylene or 2,6-difluoro-1,4-phenylene; Z1 is a single bond or —(CH2)2—; Z2 is a single bond, —(CH2)2—, —COO—, or —CF2O—; and Z3 is a single bond or —COO—.