Liquid-Crystalline Mixtures for Switchable Windows
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Solution Overview
Problem
There is a need for novel liquid-crystalline materials with a broad liquid-crystalline phase, high clearing point, low refractive index anisotropy, good solubility, and high light stability for regulating sunlight passage through switchable windows, particularly those with high thickness and requiring long-lasting performance.
Innovation Solution
A mixture comprising specific compounds of formulae (1) and (2) with defined structural variables, which form a liquid-crystalline material with a broad nematic phase, low refractive index anisotropy, and high clearing point, combined with dyes and chiral dopants for enhanced light regulation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of the layer comprising the liquid-crystalline material is increased, then the light regulation capability is improved, but the refractive index anisotropy Δn increases which degrades performance
Solution Approach 1:
The patent changes the refractive index parameter by selecting specific liquid-crystalline compounds with predetermined refractive index characteristics. The mixture is formulated to achieve a specific refractive index range (1.50-1.60) that compensates for the increased layer thickness, maintaining optimal light regulation performance despite the thicker layer configuration.
2Reliability
If dyes are added to the liquid-crystalline material to enhance light absorption, then light stability is improved, but solubility and solution stability deteriorate
Solution Approach 1:
The patent creates a composite system by formulating a specific mixture of liquid-crystalline compounds (compounds I and II) that work synergistically. This composite material structure provides enhanced solubility for the dye components while maintaining solution stability and light stability, as the specific combination of liquid-crystalline compounds creates an optimized molecular environment for dye dissolution and stability.
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 mixture provides a stable and efficient means to regulate sunlight passage, maintaining performance across a wide temperature range and ensuring homogeneous light transmission, suitable for use in switchable windows with high thickness and varying light conditions.
Implementation Method 1
Liquid-crystalline materials which comprise dyes... uses liquid-crystalline materials... has a broad liquid-crystalline phase of the material, in particular a high clearing point of 100° C. or higher
Implementation Method 2
a small value for the refractive index anisotropy Δn, in particular a value of Δn of less than 0.065
Implementation Method 3
For the purposes of the present application, the term light is taken to mean, in particular, electromagnetic radiation in the UV-A, VIS and NIR regions... high light stability of the liquid-crystalline material, in particular of the liquid-crystalline material comprising dyes
Data Source
AI summary
The present application relates to mixtures which have liquid-crystalline properties. The application furthermore relates to the use of the mixtures in devices which regulate the transmission of light through an area element.