Emission Layer Material for Inkjet OLEDs
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Solution Overview
Problem
Existing methods for producing organic electroluminescent elements using coating techniques face challenges such as clogging of inkjet heads and limited suitability for continuous inkjet coating, as well as concerns about crosslinking treatments affecting emission layer performance.
Innovation Solution
A material for the emission layer comprising a luminescent material and specific compounds from groups (A), (B), and (C), which are used to form an organic electroluminescent element capable of high luminescent efficiency and suitable for inkjet coating methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an inkjet method is used to form layers of organic electroluminescent elements, then large substrates can be processed and production efficiency is improved, but inkjet head clogging occurs and continuous coating suitability is limited
Solution Approach 1:
The patent applies parameter changes by carefully selecting organic solvents with specific boiling points (200°C or higher) and molecular weights (150 or higher) to optimize the coating composition. This resolves the contradiction by adjusting solvent parameters to prevent inkjet head clogging while maintaining high production efficiency for large substrate processing
Solution Approach 2:
The patent employs disposable-like maintenance strategies for the inkjet head through regular cleaning protocols and replacement of consumable components. This allows continuous operation and prevents clogging-related downtime, maintaining high productivity while ensuring reliable operation
2Stability of the object's composition
If crosslinking treatment is applied to lower layers to prevent elution, then layer stability is improved, but emission layer performance may be compromised due to resistance to crosslinking treatment
Solution Approach 1:
The patent introduces an intermediary approach by using specific organic solvents that do not dissolve lower layer materials, creating a natural barrier that prevents elution without requiring crosslinking treatment. This intermediary solvent selection resolves the contradiction by maintaining layer stability while preserving emission layer performance
Solution Approach 2:
The patent extracts the crosslinking treatment step from the process by relying on solvent selection criteria (boiling point ≥200°C, molecular weight ≥150) to prevent elution. This extraction eliminates the harmful effects of crosslinking on emission layer performance while maintaining necessary layer stability
3Stability of the object's composition
If crosslinking groups are introduced into emission layer to prevent elution, then elution resistance is improved, but unreacted crosslinking groups may react during driving to cause luminance decrease
Solution Approach 1:
The patent completely extracts the crosslinking group introduction step from the emission layer formation process. Instead, it uses carefully selected organic solvents with high boiling points and molecular weights that naturally prevent elution without introducing reactive crosslinking groups. This resolves the contradiction by eliminating the source of harmful reactions while maintaining elution resistance
Solution Approach 2:
The patent uses the organic solvent as an intermediary that provides elution resistance through its physical properties (boiling point ≥200°C, molecular weight ≥150) rather than through chemical crosslinking. This intermediary approach prevents both elution and subsequent harmful reactions during device operation, preserving luminance
4Productivity
If coating method is used for emission layer, then advantage of coating method is utilized, but layers above emission layer cannot be formed by coating method
Solution Approach 1:
The patent applies universality by developing a coating composition formulation that can be used for multiple layer types (emission layer and electron transport layer). The specific solvent selection criteria (boiling point ≥200°C, molecular weight ≥150) create a universal coating approach that works across different layer functions, resolving the limitation of coating method versatility
Data Source
AI summary
The present invention relates to a material for an emission layer of an organic electroluminescent element, including at least a luminescent material and at least two kinds of compounds respectively selected from at least any two groups among three groups represented by the following (group A), (group B), and (group C). (Group A): a group consisting of a compound represented by the following formula (1-A) and a compound represented by the following formula (1-B); (group B): a compound represented by the following formula (2); and (group C): a group consisting of a compound represented by the following formula (3), a compound represented by the following formula (1-1), and a compound represented by the following formula (1-2) (details of each formula included in (group A) to (group C) are as described in the description).