Hyperbranched Polymer Hole Injection Layer for OLED Moisture Resistance
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Solution Overview
Problem
Existing organic light-emitting diodes face issues with moisture sensitivity in hole injection layers, leading to impurities and reduced efficiency and lifetime, particularly with materials like PEDOT:PSS which are vulnerable to moisture during the wet processing of forming hole injection layers.
Innovation Solution
A hyperbranched polymer with excellent hole injection and electron blocking capabilities, as well as adhesive properties with electrodes, is developed, allowing for the formation of an organic light-emitting diode layer that can be dissolved in organic solvents and processed under a moisture-free inert gas atmosphere using a simple wet process like spin coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PEDOT:PSS is used as hole injection layer material and processed by wet process, then ease of manufacture is improved, but reliability deteriorates due to moisture sensitivity
Solution Approach 1:
The patent changes the chemical composition parameters of the hole injection layer by developing a hyperbranched polymer with specific functional groups (carboxyl, sulfonic acid, or phosphonic acid groups) that provide both moisture resistance and good hole injection capability. This parameter change allows the material to maintain ease of wet processing while improving reliability through inherent moisture resistance
Solution Approach 2:
The patent creates a composite material system by combining the hyperbranched polymer backbone with specific functional end groups (carboxyl, sulfonic acid, or phosphonic acid). This composite structure provides multiple functions: the backbone provides structural stability and moisture resistance, while the functional groups provide hole injection capability and adhesion to electrodes
2Ease of manufacture
If water-soluble material is used for hole injection layer, then ease of manufacture is improved, but object-affected harmful factors worsen due to moisture contamination
Solution Approach 1:
The patent creates an inert environment by using organic-soluble hyperbranched polymers that can be processed in organic solvents under inert gas atmospheres. This prevents moisture contamination during the wet processing stage while maintaining the benefits of solution processing. The organic solvent system acts as a protective environment that excludes water
Solution Approach 2:
The patent uses organic solvents that can be completely evaporated after coating, leaving no residual moisture. The organic solvent serves as a temporary carrier that is completely removed, unlike water-soluble materials that leave behind moisture that can contaminate the device
3Productivity
If simple wet process is used for manufacturing, then productivity is improved, but manufacturing precision worsens due to moisture sensitivity
Solution Approach 1:
The patent changes the processing parameters by using organic solvents with controlled evaporation rates and processing temperatures that prevent moisture ingress. The hyperbranched polymer's solubility in organic solvents allows for precise control of film formation parameters while maintaining simple wet processing steps
Data Source
AI summary
Provided are a hyperbranched polymer represented by Formula 1 below, an organic light-emitting diode including an organic layer including the hyperbranched polymer, and a method of manufacturing the organic light-emitting diode:For a detailed description about Formula 1, the Detailed Description of the Invention may be referred to. The hyperbranched polymer is excellent in view of hole injection capability and/or electron blocking capability and adhesion with an electrode, and thus, the organic light-emitting diode including the organic layer including the hyperbranched polymer can have good electrical properties.