Polymerizable Liquid Crystal Films for Wideband Retardation
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Solution Overview
Problem
Existing retardation films struggle with accurate λ/4 or λ/2 retardation over a wide wavelength band, leading to colored polarized light and inhomogeneous optical performance due to wavelength dispersion issues and the presence of tilt domains and disclinations.
Innovation Solution
Development of novel polymerizable anisotropic liquid crystals (LCPs) with a hydrazine-benzothiazole core, which can be formulated into compounds and compositions that form optical films with improved solubility and alignability, allowing for uniform polarized light conversion and reduced tilt domains, thereby achieving a reverse retardation pattern over a wide wavelength band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional retardation films are used to achieve λ/4 or λ/2 retardation, then specific monochromatic light conversion is achieved, but the polarized light is converted into coloured polarized light and accurate retardation cannot be maintained over the entire wavelength band
Solution Approach 1:
The patent modifies the molecular structure of liquid crystal compounds by introducing a hydrazine-benzothiazole core with specific substituent patterns (formula I), which changes the optical parameters of the material. This structural modification enables reverse wavelength dispersion characteristics that maintain accurate retardation across a broad wavelength spectrum while eliminating coloration effects.
Solution Approach 2:
The invention creates composite liquid crystal compositions by combining the novel hydrazine-benzothiazole core compounds with other liquid crystal materials and additives. These composite formulations achieve synergistic effects that broaden the wavelength bandwidth for accurate retardation while maintaining uniform optical performance and eliminating tilt domains.
2Reliability
If LCP films are prepared with conventional compounds, then retardation function is achieved, but tilt domains and disclinations occur resulting in inhomogeneous optical performance
Solution Approach 1:
The patent introduces specific local structural features in the liquid crystal molecules, including the hydrazine-benzothiazole core with particular substituent groups at defined positions. These local structural characteristics influence the molecular packing and orientation behavior, preventing the formation of tilt domains and disclinations while ensuring uniform optical properties throughout the film.
Solution Approach 2:
By changing the molecular parameters of the liquid crystal compounds (core structure, substituent types and positions), the patent modifies the physical parameters of the LCP films such as melting point, clearing point, and orientational order. These parameter changes enable the formation of homogeneous films without tilt domains or disclinations, achieving reliable optical performance.
3Manufacturing precision
If new LCP compounds with improved solubility and alignability are developed, then uniform polarized light conversion is achieved, but material charge increases
Solution Approach 1:
The patent optimizes the molecular parameters of the LCP compounds to achieve optimal balance between solubility, alignability, and material efficiency. By carefully selecting substituent groups and their positions on the hydrazine-benzothiazole core, the invention enhances solubility in common solvents and improves alignability on substrates, enabling uniform film formation with reduced material charge while maintaining high manufacturing precision.
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 LCP films exhibit excellent solubility and processability, enabling uniform polarized light conversion and a high contrast ratio, with birefringence showing reverse wavelength dispersion, improving optical performance and reducing color issues in devices like displays and TVs.
Implementation Method 1
When light passes through a retardation film, the polarization direction of the light changes because of the birefringence and the thickness of the film
Implementation Method 2
The organic solvent is subsequently removed to give a well-oriented, solvent-free LCP layer, which in turn is cross-linked to fix the liquid crystalline properties ordered structure
Data Source
AI summary
The invention relates to novel anisotropic compounds of formula ( I ) as well as to liquid crystalline mixtures, films and electro-optical devices comprising the compound.