Liquid-Crystal Medium with Coumarin Acrylate for Flexible Displays
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Solution Overview
Problem
Current liquid crystal (LC) mixtures for flexible displays suffer from insufficient phase separation between polymer walls and LC molecules, leading to reduced transparency, contrast, and mechanical stability, along with issues like non-uniform pixel size and inadequate adhesion to substrates, due to the use of polymerisable compounds with absorption maxima at shorter UV wavelengths, which do not match the emission spectra of typical UV lamps.
Innovation Solution
A liquid crystal medium comprising polymerisable compounds with a coumarin group connected to an acrylate or methacrylate group, via a hydrocarbon spacer, which enhances photopolymerisation speed and mechanical strength, allowing for the formation of polymer walls with clear phase separation and improved adhesion, while shifting absorption to higher UV wavelengths for better compatibility with flexible substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polymerisable compounds with absorption maxima at shorter UV wavelengths are used, then photopolymerisation can proceed, but the absorption does not match the emission spectra of typical UV lamps, reducing photopolymerisation efficiency
Solution Approach 1:
The patent changes the absorption wavelength parameter of the polymerisable compound by introducing a coumarin group, shifting it from shorter UV wavelengths to higher wavelengths that match the emission spectrum of typical UV lamps, thereby improving energy utilization and photopolymerisation efficiency
2Reliability
If conventional polymerisable compounds are used, then the LC mixture can be processed, but insufficient phase separation occurs between polymer walls and LC molecules, leading to reduced transparency and contrast
Solution Approach 1:
The patent introduces a coumarin group with specific optical properties that enhance the local optical characteristics of the polymer walls, improving light absorption and reducing light scattering, thereby enhancing display transparency and contrast
3Strength
If polymer walls are formed to maintain gap distance, then structural support is provided, but mechanical strength and adhesion to substrates are insufficient
Solution Approach 1:
The patent creates a composite system combining the coumarin-containing polymerisable compound with the LC host mixture, where the coumarin group forms a crosslinked polymer network that provides both mechanical strength and improved adhesion to substrates through enhanced interfacial interactions
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 proposed LC medium enables the formation of polymer walls with high mechanical strength, clear phase separation, and improved adhesion, resulting in enhanced display performance with higher transparency, contrast, and stability, suitable for flexible and unbreakable LC displays.
Implementation Method 1
The proposed LC medium enables the formation of polymer walls with high mechanical strength, clear phase separation, and improved adhesion, resulting in enhanced display performance with higher transparency, contrast, and stability
Data Source
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AI summary
The present invention relates to a liquid crystal (LC) medium comprising polymerisable compounds, to a process for its preparation, to its use for optical, electro-optical and electronic purposes, in particular in LC displays, and to LC displays comprising it.