Quantum Dot Color Filter Ink to Reduce Blue-Light Leakage
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Solution Overview
Problem
Existing quantum dot color filters (QDCFs) in liquid crystal displays (LCDs) suffer from blue light leakage, leading to color contamination and reduced external quantum efficiency due to low optical density and poor forward light out-coupling, particularly when using QDs with small absorption cross-sections in the blue region, and increasing QD concentration compromises viewing angle and efficiency.
Innovation Solution
Incorporating blue light-absorbing materials that preferentially absorb blue light relative to red or green light, combined with quantum dots, in the QDCF layers, to form optically dense films that reduce blue light leakage and enhance efficiency, using ink compositions containing di(meth)acrylate monomers, multifunctional crosslinking agents, and luminescent materials for energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the concentration of quantum dots is increased to achieve increased blue light absorption and optical density, then blue light absorption is improved, but viewing angle is compromised and re-absorption of emitted photons occurs causing reduction in external quantum efficiency
Solution Approach 1:
The patent combines quantum dots with a blue light-absorbing material having a broad absorption spectrum in the blue region and peak absorption at 450 nm. This composite material approach allows the system to achieve high blue light absorption through the synergistic effect of QDs and the blue light-absorbing material, while avoiding the need to excessively increase QD concentration that would cause viewing angle degradation and re-absorption losses.
Solution Approach 2:
The patent introduces a blue light-absorbing material with specific optical parameters (broad absorption spectrum in blue region, peak at 450 nm) to complement the quantum dots. This parameter optimization allows the system to achieve desired optical density and blue light absorption without excessive QD concentration, thereby maintaining viewing angle and external quantum efficiency.
2Illumination intensity
If the thickness of the quantum dot layer is increased to achieve increased blue light absorption, then optical density is improved, but viewing angle is compromised due to parallax issues
Solution Approach 1:
The patent uses a composite structure where blue light-absorbing material with broad spectral absorption is combined with quantum dots. This composite approach enables enhanced blue light absorption through the material combination rather than increasing layer thickness, thereby avoiding parallax-induced viewing angle degradation while achieving the desired optical density.
3Illumination intensity
If multiple re-absorption events occur in high quantum dot concentration layers, then blue light absorption is increased, but spectral red shift occurs leading to color distortion
Solution Approach 1:
The patent combines quantum dots with a blue light-absorbing material that has a broad absorption spectrum peaking at 450 nm. This composite material system achieves high blue light absorption through the synergistic effect of both components, reducing the need for high QD concentration that would cause multiple re-absorption events and spectral red shift, thereby maintaining color accuracy.
Solution Approach 2:
The introduction of the blue light-absorbing material with specific spectral parameters (broad absorption, peak at 450 nm) allows the system to achieve desired optical absorption without excessive QD concentration. This parameter optimization prevents spectral red shift and color distortion while maintaining high blue light absorption efficiency.
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 effectively reduces blue light leakage, improves color gamut, and enhances external quantum efficiency by at least 4% to 40% in QDCF layers, maintaining viewing angle and reducing spectral red shift.
Implementation Method 1
the blue light-absorbing material is characterized in that it preferentially absorbs blue light relative to red light or green light
Implementation Method 2
the blue light-absorbing material transfers energy to the quantum dots when the device is in operation
Implementation Method 3
the QDs 'filter' incoming light having a first wavelength or wavelength range, such as blue light, by converting at least a portion of it into light having a different wavelength or wavelength range, such as red light and/or green light
Data Source
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AI summary
Liquid ink compositions containing quantum dots for optoelectronic display applications are provided. Also provided are solid films formed by drying the ink compositions, optical elements incorporating the solid films, display devices incorporating the optical elements, and methods of forming the solid films, optical elements, and the devices. Liquid ink compositions and solid films made by drying the liquid ink compositions include one or more blue light-absorbing materials in combination with red light-emitting QDs or green light-emitting QDs.