Quantum Dot Light-Emitting Element Protection Against Ligand Elution
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Solution Overview
Problem
In existing light-emitting elements, the ligand elution from the light-emitting layer into the solution applied to the quantum dot layer leads to defects, causing non-radiative recombination of electrons and holes, resulting in reduced luminous efficiency and reliability.
Innovation Solution
The light-emitting element incorporates a first ligand coordinated to the quantum dot and a second ligand in the contact layer, both having the same functional group, such as halide or chalcogenide ions, to compete with each other's dissolution in the solvent, thereby reducing ligand elution and protecting the quantum dot surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a solution containing an electron transport material is applied onto the light-emitting layer, then the electron transport layer is formed, but the ligand is eluted from the light-emitting layer into the solution
Solution Approach 1:
A sealant layer is introduced as an intermediary between the light-emitting layer and the electron transport layer. This sealant layer prevents direct contact between the solution containing electron transport material and the light-emitting layer, thereby blocking the elution path of ligands while still allowing for formation of the electron transport layer above the sealant.
Solution Approach 2:
The sealant layer is applied in advance to the light-emitting layer before applying the electron transport layer. This preliminary action creates a protective barrier that prevents ligand elution during subsequent processing steps, addressing the problem before it can occur.
2Adaptability or versatility
If the ligand is removed from the quantum dot, then the quantum dot surface is exposed, but defects are exposed and non-radiative recombination occurs
Solution Approach 1:
The sealant layer acts as a protective intermediary that prevents solution components from accessing and removing ligands from the quantum dot surface, thereby maintaining quantum dot integrity and preventing defect formation while still allowing the device structure to be completed.
Solution Approach 2:
The sealant layer provides beforehand protection to the light-emitting layer, cushioning against the harmful effects of solution application by preventing ligand removal and quantum dot degradation before they can occur.
3Volume of moving object
If the quantum dot increases in size due to Ostwald growth or aggregation, then the quantum dot grows, but luminous efficiency and reliability are reduced
Solution Approach 1:
The sealant layer serves as a protective barrier that prevents direct interaction between the solution and quantum dots, thereby preventing Ostwald growth and aggregation that would otherwise occur upon exposure to the solution environment.
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
This configuration enhances the luminous efficiency and reliability of the light-emitting element by minimizing ligand elution and maintaining the quantum dot's integrity.
Implementation Method 1
the first ligand and the second ligand have an identical functional group, each of the first ligand and the second ligand is a halide ion, or each of the first ligand and the second ligand is a chalcogenide ion
Data Source
AI summary
A light-emitting layer includes a quantum dot and a first ligand to be coordinated to the quantum dot, an electron transport layer is in contact with the light-emitting layer and includes a second ligand, and the first ligand and the second ligand have the same functional group, are each a halide ion, or are each a chalcogenide ion, the light-emitting layer includes a first metal element having an ionization tendency equal to or higher than an ionization tendency of lead, the first contact layer includes a second metal element having an ionization tendency equal to or higher than the ionization tendency of lead, the first metal element is selected from a group including alkali metals and alkaline earth metals, and the second metal element is selected from the group including alkali metals and alkaline earth metals.