Organic EL Element Using Triplet Energy Host Material
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Solution Overview
Problem
Existing organic electroluminescent elements face limitations in achieving high external quantum efficiency, particularly in the blue region, and suffer from low durability when using triplet light-emitting materials.
Innovation Solution
An organic electroluminescent element incorporating a compound represented by a specific general formula (Z) in one or more organic compound layers, including a light-emitting layer, which enhances light-emitting efficiency and durability by optimizing the triplet energy level and layer composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a triplet light-emitting material is used to improve internal quantum efficiency, then external quantum efficiency is improved, but durability of the element deteriorates
Solution Approach 1:
The patent changes the energy level parameter of the host material by selecting a host with a lowest triplet energy level lower than that of the light-emitting material. This parameter adjustment allows efficient triplet energy transfer while improving durability by preventing exciton accumulation in the host material.
Solution Approach 2:
The host material acts as an intermediary between the triplet light-emitting material and the electrodes. It facilitates energy transfer from the light-emitting material while its specific energy level configuration prevents degradation, thus mediating between efficiency and durability requirements.
2Productivity
If a host material with the lowest triplet energy level lower than the light-emitting material is used to improve external quantum efficiency, then light-emitting efficiency is improved, but durability deteriorates
Solution Approach 1:
The patent optimizes the energy level parameter by selecting a host material whose lowest triplet energy level is specifically lower than that of the light-emitting material. This precise parameter matching enables efficient energy transfer while the host's energy level configuration prevents exciton accumulation that would cause degradation.
3Adaptability or versatility
If a compound with multiple imidazole skeletons connected through a linking group is used, then structural flexibility is improved, but lowest triplet energy level becomes low causing luminous efficiency to deteriorate
Solution Approach 1:
The patent applies local quality by using different types of compounds in different layers. The light-emitting layer contains the triplet light-emitting material with specific local molecular structure, while the host material in adjacent layers has optimized energy levels. This local differentiation allows structural flexibility in the light-emitting material while maintaining high triplet energy levels in the host for efficient energy transfer.
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 solution achieves improved external quantum efficiency and extended durability by incorporating the compound with a triplet energy level of 65 kcal/mol or more, leading to enhanced light-emitting performance and prolonged luminance half-life.
Implementation Method 1
An organic electroluminescent (EL) element has attracted attention since it can provide luminescence with a high luminance at a low voltage
Implementation Method 2
an element (a triplet light-emitting element) using a triplet light-emitting material (phosphorescent luminescence material)
Data Source
AI summary
An organic electroluminescent element comprises: a pair of electrodes; and one or more organic compound layers at least one of which is a light-emitting layer, the one or more organic compound layers being provided between the pair of electrodes, wherein at least one of the one or more organic compound layers comprises a compound represented by general formula (Z):wherein R31 and R32 each represents a hydrogen atom or a substituent, R3A represents a substituent other than an aromatic hetero ring connected through a nitrogen atom, or a hydrogen atom, X31 to X38 each represents a substituted or unsubstituted carbon atom or a nitrogen atom, and Y31 to Y33 each represents a nitrogen atom or C—R3B (wherein R3B represents a substituent other than an aromatic hetero ring connected through a nitrogen atom, or a hydrogen atom).