Lithium-Boron Complex for OLED Electron Injection
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Solution Overview
Problem
Existing organic light emitting elements face stability issues due to the use of water-soluble electron injecting materials like lithium fluoride, which lead to reduced stability and increased voltage requirements, especially when used in electron transport layers.
Innovation Solution
A lithium complex compound with a specific general formula is introduced, featuring a six-membered ring structure with boron and pyrazole groups, which is less reactive to water and has improved stability, used in contact with electrodes to enhance charge injection properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If water-soluble electron injecting materials like lithium fluoride are used, then electron injecting property is improved, but stability of the light emitting element is reduced
Solution Approach 1:
The patent changes the chemical composition parameter of the electron injecting material from conventional water-soluble lithium fluoride to a water-insoluble lithium complex compound with specific ligands (beta-diketonate, carboxylate, or alkoxide). This parameter change maintains good electron injecting property while eliminating the water solubility issue that causes stability problems.
Solution Approach 2:
The patent uses a composite material approach by forming a complex between lithium ion and organic ligands (beta-diketonate, carboxylate, or alkoxide). This composite structure combines the electron injecting capability of lithium with the water-insolubility and stability of the organic ligand framework, resolving the contradiction between injecting performance and stability.
2Ease of operation
If metal salt such as lithium fluoride is used as electron injecting material, then charge injecting property is improved, but voltage requirement increases
Solution Approach 1:
The patent changes the chemical structure parameter of the electron injecting material to a lithium complex compound with specific ligands, which modifies the electronic properties at the electrode interface. This parameter change enables efficient charge injection at lower voltages compared to conventional lithium fluoride.
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 lithium complex compound enables an organic light emitting element that operates at low voltage with high luminous efficiency and excellent durability, resisting water and humidity-induced degradation.
Implementation Method 1
a layer to be brought into contact with one of the pair of electrodes in the organic compound layer contains a lithium complex compound
Implementation Method 2
A hole and an electron to be injected from the electrodes recombine in a light emitting layer in the organic compound layer to produce an exciton, and the organic light emitting element emits light upon return of the exciton to its ground state
Data Source
AI summary
Provided is an organic light emitting element that can be driven at a low constant voltage, exhibits high luminous efficiency, and has an excellent lifetime characteristic. The organic light emitting element includes: a pair of electrodes; and an organic compound layer arranged between the pair of electrodes, in which a layer to be brought into contact with one of the pair of electrodes in the organic compound layer contains a lithium complex compound represented by the following general formula [1]:in the formula [1], R1 to R16 each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group that may be substituted with fluorine, an alkoxy group that may be substituted with fluorine, or a substituted or unsubstituted aryl group.