OLED Hole Injection Layer Coating Composition
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Solution Overview
Problem
The existing methods for manufacturing organic light emitting diodes (OLEDs) using a solution process face challenges such as high equipment costs, limited scalability, and layer damage due to solvent interactions, leading to reduced device lifetime and efficiency.
Innovation Solution
A coating composition comprising an organic metal complex of a transition metal, a fluorine-based polymer with sulfonic acid or sulfonate groups, and an organic solvent is used to form a stable hole injection or transfer layer, which improves interfacial properties and maintains high efficiency with low driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a solution process is used to manufacture OLEDs, then manufacturing costs are reduced and large area devices can be manufactured, but lower layers are damaged by solvents causing mixing with upper layers
Solution Approach 1:
The patent introduces a hole injection layer as an intermediary layer between the lower electron transport layer and upper layers. This hole injection layer acts as a protective barrier that prevents solvent from reaching and damaging the electron transport layer materials, thereby maintaining layer integrity while still allowing the solution process to proceed
Solution Approach 2:
The hole injection layer is formed in advance before depositing upper layers that require solution processing. This preliminary action creates a protective interface that prevents subsequent solvent damage to lower layers, enabling the use of solution processes for upper layers without compromising device reliability
2Use of energy by moving object
If conductive polymer with acidic dopant is used for hole injection layer, then low operating voltage is obtained, but electrode materials are damaged reducing device lifetime
Solution Approach 1:
The patent changes the chemical parameter (pH) of the hole injection layer by using non-acidic dopants instead of traditional acidic dopants. This parameter change maintains the electrical functionality (low operating voltage) while eliminating the harmful chemical effect (acid damage to electrodes), thereby extending device lifetime
Solution Approach 2:
The patent uses strong oxidizing agents like ferric chloride or ammonium persulfate as dopants for the hole injection layer. These oxidants provide the necessary electrical conductivity through oxidation without the acidic damage caused by traditional dopants, achieving both low operating voltage and improved device lifetime
3Manufacturing precision
If vacuum deposition process is used, then uniform deposition is achieved, but equipment investment costs and process costs are very high
Solution Approach 1:
The patent replaces the mechanical vacuum deposition system with a solution-based coating process. Instead of using expensive vacuum deposition equipment to achieve uniform layers, the invention uses solution processing with controlled drying and heat treatment to achieve uniform deposition at lower cost
Solution Approach 2:
The patent changes the deposition method from physical vapor deposition to liquid solution deposition. By controlling parameters such as solution concentration, coating speed, and drying conditions, uniform layers can be achieved through solution processing without requiring expensive vacuum equipment
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
The solution enables the formation of a stable and efficient hole injection or transfer layer, resulting in a long-lasting OLED with reduced voltage requirements and improved coatability, addressing the limitations of existing solution processes.
Implementation Method 1
The sulfonic acid has an oxidizing power and is thereby used as an oxidizer. Accordingly, by the sulfonic acid, an organic material ligand of the organic metal complex is readily removed even under inert atmosphere such as nitrogen and is smoothly converted to a metal oxide
Implementation Method 2
the coating composition including an organic metal complex of a transition metal; a polymer including a unit of the following Chemical Formula 1-2; and an organic solvent
Data Source
Figure 1~2
AI summary
The present specification relates to a hole injection or transfer layer coating composition of an organic light emitting diode comprising an organic metal complex of a transition metal; a fluorine-based polymer comprising sulfonic acid or sulfonate; and an organic solvent, a method for manufacturing an organic light emitting diode and an organic light emitting diode using the same.