Halogen-Rich Quantum Dot Shells for Surface Defect Reduction
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Solution Overview
Problem
Quantum dot light emitting diodes (QD-LEDs) face challenges in maintaining high photoluminescence intensity and lifespan due to surface defects caused by the removal of oleic acid ligands during the synthesis process, which hinders electron and hole transport.
Innovation Solution
Introducing halogen elements such as fluorine, chlorine, or iodine into the quantum dot shell, with a higher concentration on the outer surface to effectively remove oleic acid ligands and minimize surface defects, resulting in improved photoluminescence intensity and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oleic acid ligand removal post-treatment is performed on quantum dots, then manufacturing process is completed, but photoluminescence intensity and lifespan are reduced due to surface defects
Solution Approach 1:
The patent applies preliminary action by introducing halogen elements during the shell formation process before the oleic acid ligand removal step. This pre-introduction of halogen elements (Fluorine, Chlorine, Bromine, or Iodine) into the shell structure prepares the quantum dot to resist surface defect formation during subsequent ligand removal, thereby maintaining photoluminescence intensity and lifespan while completing the manufacturing process.
2Reliability
If halogen elements are introduced into the shell to remove oleic acid ligand, then surface defects are minimized, but shell structure complexity increases
Solution Approach 1:
The patent applies local quality by concentrating halogen elements specifically in the outer region of the shell rather than uniformly distributing them throughout the entire shell structure. This localized introduction of halogen elements (Fluorine, Chlorine, Bromine, or Iodine) at the outer shell region effectively targets the oleic acid ligand removal function while minimizing the overall structural complexity compared to uniform distribution approaches.
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 introduction of halogen elements enhances the quantum yield to at least 70% and extends the lifespan of quantum dots by effectively removing oleic acid ligands and reducing surface defects, leading to improved performance and efficiency in light emission.
Implementation Method 1
Introduce halogen elements such as fluorine, chlorine, or iodine into the quantum dot shell, particularly concentrating them on the outer surface to effectively remove the oleic acid ligand and minimize surface defects
Implementation Method 2
electrons and holes injected from electrodes meet at the p-n junction and generate light having a wavelength corresponding to an energy band gap
Implementation Method 3
The QD-LEDs provide improved performance by exploiting a quantum confinement effect resulting from sizes of the nanoscale semiconductor crystals of the quantum dots
Data Source
AI summary
A quantum dot of a light emitting device, includes: a core; and a shell around the core and including halogen elements of at least one type, wherein a first number per unit volume of halogen elements in a first area of the shell, that includes an outer surface of the shell, is larger than a second number per unit volume of halogen elements in a second area of the shell other than the outer surface of the shell.