Organic Electroluminescent Device Host Material Combination
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Solution Overview
Problem
Current organic electroluminescent devices, particularly those using triplet emission, face challenges in efficiency, operating voltage, and service life, despite advancements in host and matrix materials.
Innovation Solution
A combination of specific electron-transporting and hole-transporting host materials, including diazadibenzofuran or diazadibenzothiophene units and biscarbazole derivatives, is used in the light-emitting layer of organic electroluminescent devices to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional host materials are used in organic electroluminescent devices, then device construction is straightforward, but service life is insufficient
Solution Approach 1:
The patent employs composite host materials comprising specific combinations of electron-transporting materials (ETM) and hole-transporting materials (HTM) with defined weight ratios. This composite approach enables synergistic effects where the ETM component facilitates electron injection and transport while the HTM component manages hole transport, resulting in improved device service life that neither material could achieve alone.
Solution Approach 2:
The patent systematically varies the weight ratios of ETM to HTM components in the host material mixture to optimize device performance. By adjusting these compositional parameters, the invention achieves optimal balance between electron and hole transport, thereby maximizing service life while managing the complexity of material formulation.
2Use of energy by moving object
If phosphorescent emitters are used to achieve triplet emission, then efficiency can be improved, but operating voltage increases
Solution Approach 1:
The patent assigns specific functional roles to different components within the light-emitting layer. The electron-transporting host material is selected with specific properties (electron mobility, LUMO levels) optimized for electron transport, while the hole-transporting host material is selected with properties (hole mobility, HOMO levels) optimized for hole transport. This local optimization of material properties enables efficient triplet emission while managing operating voltage through balanced charge transport.
3Reliability
If host material combinations are used to improve device properties, then service life increases, but material selection complexity increases
Solution Approach 1:
The patent divides the host material system into distinct functional segments: electron-transporting materials with specific characteristics (electron mobility ≥ 10^-6 cm²/Vs, LUMO levels between -2.0 to -3.5 eV) and hole-transporting materials with specific characteristics (hole mobility ≥ 10^-6 cm²/Vs, HOMO levels between 5.5 to 6.5 eV). This segmentation allows independent optimization of each material component's properties while maintaining overall system compatibility through defined interface requirements.
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 material combination improves the service life and maintains or reduces the operating voltage of organic electroluminescent devices while maintaining efficiency, especially when used with specific emitters and monoamines in the emission and injection layers.
Implementation Method 1
organic electroluminescent device comprising a light-emitting layer comprising an electron-transporting host material and a hole-transporting host material
Implementation Method 2
The electron-transporting host material corresponds to a compound of formula (1) containing diazadibenzofuran or diazadibenzothiophene units
Implementation Method 3
The hole-transporting host material corresponds to a compound of formula (2) from the class of biscarbazoles or derivatives thereof
Data Source
AI summary
The present invention relates to an organic electroluminescent device containing a light-emitting layer that comprises an electron-transporting host material and a hole-transporting host material, as well as to a formulation containing a mixture of the host materials and a mixture containing the host materials. The electron-transporting host material corresponds to a compound of formula (1) containing diazadibenzofurane units or diazadibenzothiophene units. The hole-transporting host material corresponds to a compound of formula (2) from the class of biscarbazoles or derivatives thereof.