Light-Scattering Liquid Crystal Composition for Smart Windows
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Solution Overview
Problem
Light-scattering liquid crystal devices of the reverse mode type face challenges in achieving excellent transparency when no voltage is applied and require high driving voltages due to insufficient alignment of liquid crystal molecules and strong anchoring forces from the polymer network.
Innovation Solution
A liquid crystal composition containing a polymerizable compound with specific groups, such as those represented by general formula (1), and a compound with negative dielectric anisotropy is used to form a polymer network, enhancing alignment and reducing driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high order alignment of liquid crystal molecules and mesogen group in polymer network is achieved in reverse mode type, then transparency when no voltage is applied is improved, but driving voltage becomes excessively high due to strong anchoring force
Solution Approach 1:
The patent changes the chemical structure parameters of the polymerizable compound by introducing specific groups (carboxyl, carbonyl, cyano, or nitro groups) that can form hydrogen bonds. This parameter change modifies the interaction strength between liquid crystal molecules and polymer network, reducing the anchoring force while maintaining alignment quality, thereby lowering driving voltage while preserving transparency.
Solution Approach 2:
The patent creates a composite system where the polymer network contains specific functional groups that interact with liquid crystal molecules through hydrogen bonding. This composite material approach allows the polymer network to provide both alignment guidance and reduced anchoring strength, simultaneously achieving transparency and low driving voltage.
2Device complexity
If alignment of liquid crystal molecules with mesogen group in polymer network is insufficient, then device configuration is simplified, but white turbidity remains in transparent state due to local light scattering
Solution Approach 1:
The patent modifies the chemical parameters of the polymerizable compound by incorporating specific functional groups that enhance alignment through hydrogen bonding interactions. This parameter change improves the alignment quality between liquid crystal molecules and polymer network, suppressing light scattering and white turbidity while maintaining the simplicity of the device configuration without requiring additional alignment layers.
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 solution achieves excellent transparency without voltage and lowers the driving voltage in light-scattering liquid crystal devices, addressing the issues of alignment and anchoring forces.
Implementation Method 1
a polymer network is formed by polymerizing the polymerizable compound
Implementation Method 2
the liquid crystal molecules in the device receives a strong anchoring force by the alignment with the mesogen group in the polymer network
Implementation Method 3
the display device has a merit of realizing a bright display... becomes a transparent state when no voltage is applied and becomes a scattering state when a voltage is applied
Data Source
AI summary
The present invention relates to a liquid crystal composition for a light-scattering liquid crystal device shown in FIG. 1 containing a polymerizable compound selected from the group consisting of compounds represented by the following general formula (1) as a first component and containing a compound having a negative dielectric anisotropy as a second component, a light-scattering liquid crystal device using the liquid crystal composition, and a smart window using the light-scattering liquid crystal device. A reverse mode type light-scattering liquid crystal device can have excellent transparency when no voltage is applied and a reduced driving voltage by the liquid crystal composition of the present invention.