Quantum Dot Color Filter Ink for Blue Leakage and Re-Absorption
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Solution Overview
Problem
Existing quantum dot color filters (QDCFs) in liquid crystal displays (LCDs) suffer from blue light leakage and reduced external quantum efficiency due to poor blue light absorption and re-absorption, leading to color contamination and compromised viewing angle.
Innovation Solution
Incorporation of blue light-absorbing materials with quantum dots in QDCF layers, specifically designed to preferentially absorb blue light, combined with luminescent materials for energy transfer to enhance efficiency, reduces blue light leakage and improves external quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the concentration of quantum dots is increased to achieve increased blue light absorption and optical density, then blue light leakage is reduced, but re-absorption of emitted photons occurs causing reduction in external quantum efficiency
Solution Approach 1:
The patent applies local quality by creating spatially differentiated QD concentrations and sizes within the color filter layer. Different regions contain QDs with optimized properties for their specific function: some areas have higher concentration for absorption, while others have lower concentration to minimize re-absorption. The use of QDs with different size distributions (affecting emission wavelengths) in different locations allows simultaneous optimization of absorption and emission efficiency in various parts of the filter.
Solution Approach 2:
The patent changes key parameters including QD concentration, QD size distribution, and layer thickness to resolve the contradiction. By adjusting these parameters, the optical density for blue light absorption is optimized without creating excessive re-absorption of emitted photons. Specific embodiments mention using QDs with sizes ranging from 2-10 nm to control emission wavelengths and absorption characteristics, thereby balancing absorption efficiency with emission efficiency.
2Object-affected harmful factors
If the thickness of the quantum dot layer is increased to improve blue light absorption, then optical density increases, but viewing angle is compromised due to parallax issues
Solution Approach 1:
The patent addresses the thickness-viewing angle contradiction by introducing additional dimensional control through lateral positioning and angular optimization. Instead of simply increasing thickness, the invention optimizes the lateral distribution of QDs and the angular characteristics of light extraction. The patent mentions optimizing the viewing angle by controlling the emission pattern and using specific QD arrangements that maintain color accuracy across different viewing angles, effectively adding angular dimension to the optimization.
3Object-affected harmful factors
If very high quantum dot concentrations are used to maximize blue light absorption, then optical density increases, but spectral red shift occurs leading to color distortion
Solution Approach 1:
The patent applies segmentation by dividing the QD population into multiple groups with different size distributions and emission characteristics. Instead of using a single high-concentration QD layer, the invention uses multiple layers or regions with different QD sizes (e.g., 2-5 nm, 5-8 nm, 8-10 nm) that emit at different wavelengths. This segmentation prevents spectral red shift by ensuring that each segment operates at optimal concentration without excessive re-absorption, thereby maintaining overall color accuracy.
Solution Approach 2:
The patent creates composite QD systems combining multiple types of quantum dots with different properties. The composite structure includes QDs made from various materials (CdSe, CdTe, InP, perovskite) with different size distributions, creating a multi-component system that achieves superior optical performance. This composite approach allows the system to absorb blue light effectively while maintaining accurate color emission by compensating for spectral shifts through the combined emission profiles of different QD types.
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 minimizes blue light leakage, enhances color gamut, and increases external quantum efficiency by preferentially absorbing blue light and utilizing energy transfer processes, resulting in improved display performance.
Implementation Method 1
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
Implementation Method 2
a blue light-absorbing material characterized in that it preferentially absorbs blue light relative to red light or green light
Data Source
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.