Quantum Dot Light-Emitting Layer With Ionic Ligands for Higher EQE
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Solution Overview
Problem
Existing light-emitting elements using quantum dots have low external quantum efficiency (EQE), which is undesirable.
Innovation Solution
A light-emitting element with an anode, cathode, and a light-emitting layer containing quantum dots, S2−, Se2−, or Te2− anions, and nonmetallic cations like ammonium ions, which are coordinated to the quantum dots to enhance stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If inorganic ligands are used to protect the surface of quantum dots, then the stability of quantum dots is improved, but the external quantum efficiency (EQE) deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the ligands by using inorganic ligands with specific properties (divalent anions like S2-, Se2-, Te2- and nonmetallic cations) instead of conventional organic ligands. This parameter change in ligand chemistry enables both stable quantum dot protection and high external quantum efficiency by optimizing the interaction between ligands and quantum dot surfaces.
Solution Approach 2:
The patent employs composite ligand systems combining both anionic and cationic components that work synergistically. The inorganic anionic ligands provide surface protection while the nonmetallic cationic ligands facilitate charge transfer, creating a composite ligand environment that simultaneously achieves stability and high EQE.
2Ease of manufacture
If conventional ligand systems are used, then the manufacturing process is simple, but the external quantum efficiency and lifetime deteriorate
Solution Approach 1:
By changing the chemical composition parameters of the ligands to inorganic systems with specific divalent anions and nonmetallic cations, the patent achieves improved reliability and lifetime while maintaining manufacturing simplicity through straightforward incorporation into the quantum dot synthesis process.
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
Improves EQE, reduces voltage requirements, and extends the lifetime of the light-emitting element by maintaining efficient carrier injection and preventing charge transfer disruptions.
Implementation Method 1
The light-emitting layer includes a quantum dot, a plurality of first ions, and a plurality of second ions. Each of the plurality of first ions is an anion and each of the plurality of second ions is a cation.
Data Source
AI summary
A light-emitting element according to the disclosure includes a cathode, an anode, and a light-emitting layer provided between the cathode and the anode. The light-emitting layer includes a quantum dot, a plurality of first ions, and a plurality of second ions. Each of the first ions is an anion, and each of the second ions is a cation. The anion is any one of S2−, Se2−, and Te2−, and the cation is composed of a nonmetallic element.