Polymerizable Charge Transport Layer for EL Device Elution
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Solution Overview
Problem
The existing methods for forming organic electroluminescent devices using the coating method face challenges in maintaining the intended structure due to elution of previously formed organic layers and degradation of properties when a crosslinking agent is added, leading to reduced luminous efficiency and difficulty in manufacturing.
Innovation Solution
Incorporating a polymerizable compound capable of exhibiting charge transportability, such as phenyl fluorene acrylate, into the organic layers, which is polymerized to form an insoluble layer, preventing elution and maintaining the desired structure and properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a crosslinking agent is added to the coating liquid to prevent elution of the previously formed organic layer, then the insolubility of the organic layer is improved, but the luminous efficiency is reduced due to property degradation
Solution Approach 1:
The patent changes the chemical parameter of the crosslinking agent from a conventional agent to a polymerizable compound with charge transportability. This parameter change allows the crosslinking agent to maintain the insolubility function while simultaneously preserving charge transport properties, thereby preventing luminous efficiency reduction. The polymerizable compound undergoes polymerization to form crosslinked structures that prevent elution, while its inherent charge transportability ensures proper charge carrier movement in the organic EL device.
Solution Approach 2:
The polymerizable compound serves multiple functions simultaneously: (1) it acts as a crosslinking agent to prevent elution of the organic layer, (2) it provides charge transportability for proper device operation, and (3) it can be incorporated into the coating liquid without requiring separate processing steps. This multi-functionality resolves the contradiction by eliminating the need to choose between elution prevention and luminous efficiency maintenance.
2Reliability
If a polymerizable compound with charge transportability is used as a crosslinking agent, then the luminous efficiency is maintained, but the development difficulty increases due to the need to satisfy multiple properties
Solution Approach 1:
The polymerizable compound with charge transportability consolidates multiple required functions into a single material, reducing the overall system complexity. Instead of needing separate crosslinking agents and charge transport materials, one compound performs both roles, simplifying the material system and reducing development complexity despite the higher performance requirements of the multi-functional compound.
3Ease of manufacture
If the coating method is used to form multiple organic layers, then the ease of manufacture is improved, but the manufacturing precision deteriorates due to elution and mixing of organic materials
Solution Approach 1:
The patent applies preliminary action by incorporating the polymerizable compound into the organic layer during the coating process, before subsequent coating steps. This compound then polymerizes to create an insoluble barrier that prevents elution of previously formed layers. This preliminary protective action enables the coating method to be used for multiple layers while maintaining precise film thickness control, as each layer is protected from the solvent in subsequent coating operations.
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 allows for the suppression of luminous efficiency reduction and easy manufacture of organic electroluminescent devices with high luminous efficiency and intended structure, as the polymerizable compound minimizes property degradation and ensures sufficient insolubilization of organic layers.
Implementation Method 1
a polymer obtained by polymerizing a polymerizable compound capable of exhibiting charge transportability
Data Source
AI summary
An organic electroluminescent device includes a pair of electrodes and a plurality of organic layers disposed between the electrodes, and one of the organic layers includes an organic material forming the organic layers and a polymer obtained by polymerizing a polymerizable compound capable of exhibiting charge portability.