High-Molecular-Weight OLEDs via Solution Processing
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Solution Overview
Problem
High-molecular-weight organic materials are difficult to deposit using vacuum evaporation and often result in poor efficiency when using solution processes due to low glass-transition temperatures, leading to film integrity issues in OLEDs and other organic devices.
Innovation Solution
A high-molecule-based OLED with molecular weights greater than 730 g/mol, formed using a solution-process, incorporating host or guest materials with high glass and decomposition temperatures, and auxiliary layers deposited by the same method, enhancing thermal stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high molecular weight materials are used to improve thermal stability and film integrity, then thermal stability and mechanical strength are improved, but difficulty of deposition by vacuum evaporation increases
Solution Approach 1:
The patent replaces the vacuum evaporation method (physical deposition) with a solution-process method (chemical deposition). This substitution allows high molecular weight materials to be deposited effectively, as the solution process does not suffer from the same deposition difficulties that plague vacuum evaporation of large molecules. The solution process involves dissolving the material in a solvent and depositing from solution, which is much more compatible with high molecular weight compounds.
2Strength
If high molecular weight materials are used to improve film integrity, then mechanical strength is improved, but efficiency decreases when using solution-process
Solution Approach 1:
The patent changes the molecular weight parameter of the host or guest materials to be greater than 730 g/mol. This parameter change simultaneously improves film integrity while maintaining or enhancing device efficiency. The patent demonstrates that high molecular weight materials can achieve both good film formation and high electroluminescent efficiency, breaking the traditional trade-off between these two properties.
3Productivity
If low molecular weight materials are used to achieve high electroluminescent efficiency, then efficiency is improved, but mechanical strength of film integrity decreases
Solution Approach 1:
The patent inverts the traditional approach by changing the molecular weight parameter to be high (>730 g/mol) rather than low. This parameter change resolves the contradiction by showing that high molecular weight materials can achieve both high electroluminescent efficiency and high mechanical strength of film integrity, eliminating the need to choose between these two properties.
4Ease of manufacture
If low molecular weight host materials are used, then ease of fabrication is improved, but glass-transition temperature decreases causing film integrity damage
Solution Approach 1:
The patent changes the molecular weight parameter of the host materials to be high (>730 g/mol), which directly increases the glass-transition temperature. This parameter change resolves the contradiction by providing materials that are both easy to fabricate (via solution process) and have high thermal stability (high Tg), eliminating the trade-off between ease of fabrication and thermal stability.
Data Source
AI summary
The present invention discloses a high-molecule-based organic light-emitting diode (OLED) and a fabrication method thereof. The high-molecule-based OLED comprises a layer selected from a group consisting of an organic emissive layer, a first emission-auxiliary layer and a second emission-auxiliary layer. The organic emissive layer, first emission-auxiliary layer or second emission-auxiliary layer comprises a molecular material having a molecular weight of larger than approximately 730 g mol−1, and is formed by a solution-process.