Organic Electroluminescent Device Semiconducting Layer
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Solution Overview
Problem
Current organic electroluminescent devices face challenges in design flexibility and electronic property improvement due to the complexity of mass production tools and the need for balanced electron and hole injection, which is difficult to achieve with single matrix compounds.
Innovation Solution
The use of a combination of two organic compounds with specific structural and chemical properties, including C10 to C42 arene or heteroarene moieties and polar groups like phosphine oxide, to form an organic semiconducting layer with improved dipole moment and LUMO energy levels, enabling enhanced electron transport and injection properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single organic compound is used as electron transport matrix material, then the device structure is simple, but the design flexibility and electronic properties are limited
Solution Approach 1:
The patent employs composite organic semiconducting layers comprising multiple organic compounds with different functional properties. Specifically, it combines compounds with electron transport functionality, hole blocking functionality, and tailored LUMO energy levels to create a multi-component system that achieves superior design flexibility and electronic properties compared to single compounds, while maintaining compatibility with existing vacuum thermal evaporation processes
2Adaptability or versatility
If multiple evaporation sources are used in mass production tools, then material design freedom is improved, but process robustness and reliable process control deteriorate
Solution Approach 1:
The patent segments the electron transport layer into multiple functional sub-layers or zones within a single evaporation source. By controlling the deposition sequence and composition ratios of different organic compounds during evaporation, it creates a multi-functional composite material system that achieves design freedom equivalent to multiple sources while maintaining the process simplicity and reliability of a single evaporation source
Solution Approach 2:
The patent utilizes parameter changes in the organic compounds themselves (molecular weight, LUMO energy level, dipole moment, functional groups) to achieve diverse electronic properties and design flexibility. By selecting compounds with specific parameter ranges, the invention obtains tailored electron transport and hole blocking properties without requiring complex multi-source evaporation equipment
3Temperature
If organic compounds with higher molecular weight are used, then thermal stability is improved, but volatility decreases making vacuum thermal evaporation difficult
Solution Approach 1:
The patent identifies and exploits the relationship between molecular weight parameters and processing properties. It selects organic compounds within a specific molecular weight range (C10-C42 arene/heteroarene structures) that provides an optimal balance: high enough to ensure thermal stability for device operation, but low enough to maintain sufficient volatility for vacuum thermal evaporation processing. This parameter optimization enables simultaneous achievement of both thermal stability and ease of manufacture
Data Source
AI summary
Organic electroluminescent device comprising an anode, a cathode, at least one emission layer and an organic semiconducting layer; wherein the organic semiconducting layer is arranged between the at least one emission layer and the cathode; wherein the organic semiconducting layer comprises; a) a first organic compound comprising a first C10 to C42 arene structural moiety and/or a first C2 to C42 heteroarene structural moiety, wherein i) the dipole moment of the first organic compound, computed by the TURBOMOLE V6.5 program package using hybrid functional B3LYP and Gaussian 6-31G* basis set, is from 0 to 2.5 Debye; and ii) the LUMO energy level of the first organic compound in the absolute scale taking vacuum energy level as zero, computed by the TURBOMOLE V6.5 program package using hybrid functional B3LYP and Gaussian 6-31G* basis set, is in the range from −1.7 eV to −2.1 eV; and b) a second organic compound comprising a second C10 to C42 arene structural moiety and/or a second C2 to C42 heteroarene structural moiety and in addition at least one polar group selected from phosphine oxide and phosphine sulfide, wherein in) the dipole moment of the second organic compound, computed by the TURBOMOLE V6.5 program package using hybrid functional B3LYP and Gaussian 6-31G* basis set, is from 1.5 to 10 Debye; and iv) the LUMO energy level of the second organic compound in the absolute scale taking vacuum energy level as zero is less than 0.25 eV higher or lower than the LUMO energy level of the first organic compound; wherein it is provided that the first organic compound and the second organic compound are different from each other.