Cadmium-Free Quantum Dot Electroluminescent Pixels for Color Coordination
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Solution Overview
Problem
Existing electroluminescent display devices face challenges in achieving desired color coordination and brightness due to the limitations of cadmium-free quantum dots, particularly in emitting blue and green light, which affect color reproducibility and efficiency.
Innovation Solution
The use of cadmium-free quantum dots with specific core-shell structures and compositions in red, green, and blue pixels, along with charge auxiliary layers, to achieve precise wavelength differences and intensity ratios, enhancing brightness and color coordination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If cadmium-free quantum dots are used in blue and green pixels, then environmental safety and regulatory compliance are improved, but color coordination and brightness are worsened
Solution Approach 1:
The patent applies parameter changes by precisely controlling the size, composition, and shell structure of cadmium-free quantum dots to optimize their optical properties. By adjusting these parameters, the quantum dots achieve improved color coordination and brightness while maintaining environmental safety. This is evident in the detailed specifications of quantum dot compositions and their corresponding emission characteristics throughout the patent.
Solution Approach 2:
The patent employs composite materials by creating core-shell structured quantum dots with multiple layers of different semiconductor materials. These composite structures combine the advantages of different materials to achieve both non-toxicity and superior optical performance, resolving the contradiction between environmental safety and brightness/color coordination.
2Object-affected harmful factors
If cadmium-free quantum dots are used in blue and green pixels, then environmental safety is improved, but color reproducibility is worsened
Solution Approach 1:
The patent achieves improved color reproducibility through precise parameter control of quantum dot synthesis, including size distribution, composition ratios, and shell thickness. These parameter optimizations enable cadmium-free quantum dots to produce consistent and accurate colors while maintaining environmental safety.
Solution Approach 2:
The patent applies local quality by creating quantum dots with spatially varying compositions and structures, such as graded shell structures and core-shell configurations. This local variation in material properties enables precise control over emission wavelengths and color purity, achieving excellent color reproducibility without cadmium.
3Illumination intensity
If quantum dots with specific core-shell structures are used, then color coordination is improved, but device complexity is worsened
Solution Approach 1:
The patent applies segmentation by dividing the quantum dot structure into distinct functional regions (core and shell layers), where each segment performs a specific function. This segmentation enables independent optimization of different structural components to achieve superior color coordination while maintaining manufacturability.
Solution Approach 2:
The patent uses composite materials with core-shell structures to achieve improved color coordination. The multi-layer composite design allows for tailored optical properties in each layer, enabling precise color control. The complexity is managed through systematic material selection and structured assembly.
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 results in improved color reproducibility and increased brightness, with maximum luminance exceeding 150,000 cd/m² and external quantum efficiency greater than 9%, meeting desired color coordination standards.
Implementation Method 1
Light emission may be induced by application of a voltage resulting in a radiative recombination of excited charges generated between layers of the device
Implementation Method 2
The quantum dot may exhibit a quantum confinement effect
Implementation Method 3
Light emission may be induced by application of a voltage resulting in a radiative recombination of excited charges generated between layers of the device
Data Source
AI summary
An electroluminescent display device includes first and second electrode facing each other; and a quantum dot emission layer disposed between the first and second electrodes, wherein the quantum dot emission layer includes a red emission layer disposed in a red pixel, a green emission layer disposed in a green pixel, and a blue emission layer disposed in a blue pixel, wherein the red emission layer includes red light emitting quantum dots, the green emission layer includes green light emitting quantum dots, the blue emission layer includes blue light emitting quantum dots, and wherein the blue emission layer is configured to exhibit first emission spectrum including a blue luminescent peak and a first luminescent peak different from the blue luminescent peak, wherein the green emission layer is configured to exhibit a second emission spectrum including a green luminescent peak and a second luminescent peak different from the green luminescent peak.