Organic Electroluminescent Element Wet Process Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in manufacturing organic electroluminescence elements using a wet process is the difficulty in forming a stable laminated structure, which leads to non-uniform electron flow, reduced rectification ratio, and short lifetimes due to the solubility of polymer materials in solvents, affecting external extraction quantum efficiency and luminous efficiency.
Innovation Solution
An organic electroluminescence element with a laminated layer structure comprising a substrate, anode, cathode, hole injection layer, hole transport layer, and light emitting layer, where the hole transport layer contains a polymer with a specific molecular weight range (50,000 to 200,000) and a light emitting layer with multiple light emitting materials emitting in the range of 420 to 650 nm, and using a fluorinated alcohol in the electron transport layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymer materials are used in wet process for forming organic EL element layers, then ease of manufacture is improved, but reliability deteriorates due to solubility issues and unstable laminated structure
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molecular weight of polymer materials (specifically polyvinyl carbazole with weight average molecular weight of 10,000-100,000) and adjusting solvent selection and concentration parameters. This resolves the contradiction by modifying material parameters to achieve both ease of manufacture through wet process and reliability through stable film formation without excessive solubility
Solution Approach 2:
The patent uses composite materials by combining polymer materials (polyvinyl carbazole) with specific small molecule compounds (triphenylamine derivatives) in the hole transport layer, and combining multiple light emitting materials (fluorescent and phosphorescent compounds) in the light emitting layer. These composites provide both processability for wet manufacturing and stable, non-soluble film structures for reliability
2Device complexity
If multiple light emitting materials are mixed in a single light emitting layer, then device complexity is reduced, but manufacturing precision deteriorates due to difficulty in controlling material ratios
Solution Approach 1:
The patent applies parameter changes by specifying precise molecular weight ranges for polymer materials (10,000-100,000) and controlling the weight ratios of components (polymer:small molecule = 95:5 to 5:95). These parameter controls enable accurate material ratio management in the single light emitting layer, resolving the contradiction between reduced device complexity and maintained manufacturing precision
3Reliability
If polymer molecular weight is increased to decrease solubility, then reliability is improved, but ease of manufacture deteriorates due to difficulty in processing
Solution Approach 1:
The patent applies parameter changes by establishing an optimal molecular weight range (10,000-100,000) for polyvinyl carbazole. This range is high enough to provide adequate film stability and reduced solubility for reliability, but low enough to maintain good processability and ease of manufacture through wet coating methods
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 approach stabilizes the film formation process, enhances external extraction quantum efficiency, and extends the lifetime of the organic electroluminescence element while maintaining efficient light emission.
Implementation Method 1
the solubility of polymer materials in solvents, affecting external extraction quantum efficiency and luminous efficiency
Implementation Method 2
an organic electroluminescence element (hereinafter, referred to as an organic EL element) is an element provided with a constitution comprising an light emitting layer containing a light emitting substance
Data Source
AI summary
Disclosed is an organic electroluminescent element which can be produced by a wet process, has improved laminated structure, and also has improved external quantum efficiency and an improved service life. The organic electroluminescent element comprises at least an anode; a cathode and a laminated structure intercalated between the anode and the cathode, all of which are arranged on a substrate, wherein the laminated structure has at least four layers formed by a wet process, and wherein the layers produced by the wet process include at least a hole injection layer, a hole transport layer and a light-emitting layer. The organic electroluminescent element is characterized in that the hole injection layer comprises an electrically conductive polymer, the hole transport layer comprises a polymeric compound having a repeating unit represented by general formula (1), and the polymeric compound has a weight average molecular weight of 50,000 to 200,000 in terms of polystyrene content.