Cadmium-Free Quantum Dot Core with Phosphorus Precursor
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Solution Overview
Problem
Cadmium-free quantum dots with improved light emitting properties and increased blue light absorption rate are needed to address the limitations of cadmium-based quantum dots, which have environmental and health concerns, and exhibit poor stability and degraded light emitting properties.
Innovation Solution
A cadmium-free quantum dot with a multi-component core comprising indium, zinc, and phosphorus, and a second semiconductor nanocrystal shell including gallium and phosphorus, optimized with specific mole ratios and shell thicknesses to enhance optical density and blue light absorption, is developed, along with a quantum dot-polymer composite for improved luminous efficiency and light emitting characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cadmium-based quantum dots are used, then light emitting properties can be achieved, but environmental and health concerns arise due to cadmium toxicity
Solution Approach 1:
The patent removes cadmium from the quantum dot composition entirely, extracting the harmful element while maintaining the functional properties through alternative materials (indium, zinc, gallium, and phosphorus). This extraction principle directly addresses the toxicity issue while preserving light emitting capabilities.
Solution Approach 2:
The patent changes the compositional parameters by substituting cadmium with specific ratios of indium, zinc, and gallium phosphide compounds. By adjusting the mole ratios of these alternative materials, the quantum dot maintains its optical properties without the harmful cadmium element.
2Reliability
If quantum dot size and composition are controlled to improve optical properties, then light emitting characteristics enhance, but manufacturing precision requirements increase
Solution Approach 1:
The quantum dot is divided into distinct functional components: a core region with specific composition (indium, zinc, phosphorus) and a shell region (gallium phosphorus). This segmentation allows independent optimization of each region's properties while simplifying the overall manufacturing process through sequential deposition.
Solution Approach 2:
The patent employs composite material structures combining multiple semiconductor compounds (indium phosphide, zinc phosphide, gallium phosphorus) in specific ratios. This composite approach enables tailored optical properties while using well-established material synthesis techniques to manage manufacturing precision.
3Reliability
If blue light absorption rate is increased to improve luminous efficiency, then optical density at 450 nm increases, but absorption peak wavelength must be controlled below 440 nm
Solution Approach 1:
The patent applies local quality by creating distinct compositional regions within the quantum dot structure. The core region has a specific composition optimized for absorption, while the shell region provides different optical characteristics. This local differentiation enables enhanced blue light absorption at the core while controlling the overall absorption peak wavelength through the shell's influence.
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 quantum dot-polymer composite achieves enhanced blue light absorption and luminous efficiency, maintaining stability and chemical integrity, suitable for applications in display devices and bioimaging, while avoiding cadmium-related environmental issues.
Implementation Method 1
the quantum dot has an optical density at a wavelength of about 450 nm per gram of greater than or equal to about 1,100... enhanced blue light absorption
Implementation Method 2
The quantum dot... emits green light... maximum emission peak of the green light may be in a wavelength range of greater than or equal to about 500 nm
Data Source
AI summary
A quantum dot including a multi-component core including a first semiconductor nanocrystal including indium (In), zinc (Zn), and phosphorus (P) and a second semiconductor nanocrystal disposed on the first semiconductor nanocrystal, the second semiconductor nanocrystal including gallium (Ga) and phosphorus (P) wherein the quantum dot is cadmium-free and emits green light, a mole ratio (P:In) of phosphorus relative to indium is greater than or equal to about 0.6:1 and less than or equal to about 1.0, and a mole ratio (P:(In+Ga)) of phosphorus relative to indium and gallium is greater than or equal to about 0.5:1 and less than or equal to about 0.8:1, a quantum dot-polymer composite pattern including the same, and a display device.