Organic EL Hole Injection Layer Protection via Inorganic Film Masking
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Solution Overview
Problem
The surface flatness and contamination of the hole injection layer in organic EL devices are compromised during the manufacturing process, leading to decreased light emitting efficiency and increased driving voltage due to dissolution and contamination by alkaline solutions and bank residues.
Innovation Solution
A manufacturing method involving the formation of a bank using a fluorine-containing resin, which protects the hole injection layer with an inorganic film, preventing dissolution and contamination, and ensuring a uniform organic light emitting layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the bank is formed after the hole injection layer is formed, then the organic light emitting material region can be defined, but the surface of the hole injection layer is contaminated by bank residues causing work function variation
Solution Approach 1:
The inorganic film serves as a protective intermediary that prevents bank residues from contaminating the hole injection layer surface. By maintaining this protective barrier during and after the bank formation process, the hole injection layer surface remains clean and its work function remains stable.
Solution Approach 2:
The hole injection layer is formed in advance before bank formation, allowing it to be positioned and then protected by the inorganic film. This sequencing ensures the layer is ready for its electron injection function while being protected from contamination by subsequent processing steps.
2Manufacturing precision
If the bank is formed after the hole injection layer is formed, then the organic light emitting layer region can be defined, but the surface resistance of the hole injection layer increases due to contamination
Solution Approach 1:
The inorganic film acts as a protective intermediary that prevents bank residues from depositing on the hole injection layer surface. By maintaining this protective barrier, the surface resistance of the hole injection layer remains low, ensuring efficient electron transport and injection.
3Productivity
If wet-process is used for preparing the organic light emitting layer, then productivity is improved, but the hole injection layer dissolves in alkaline solution used in the wet process
Solution Approach 1:
The inorganic film is introduced as a protective intermediary that allows the wet-process to proceed without damaging the hole injection layer. This intermediary barrier enables the use of alkaline solutions for bank formation and organic layer preparation while preventing dissolution of the hole injection layer, thus maintaining both productivity and layer integrity.
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 method results in an organic EL device with a constant work function, reduced surface resistance, and improved light emitting efficiency, achieving low driving voltage and long product lifetime.
Implementation Method 1
an inorganic film which covers the hole injection layer is formed, a bank is formed on the inorganic film, and then the inorganic film on the hole injection layer is removed by etching using the bank as a mask
Implementation Method 2
the surface of the hole injection layer is contaminated by the residues of the bank... an inorganic film which covers the hole injection layer is formed
Implementation Method 3
the inorganic film on the hole injection layer is removed by etching using the bank as a mask
Implementation Method 4
a hole injection layer is arranged between the anode and the organic light emitting layer. The hole injection layer has a function to support the injection of holes from the anode to the organic light emitting layer
Data Source
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AI summary
Disclosed is a method for manufacturing an organic EL device which comprises a hole injection layer having a flat surface that is not contaminated. Specifically disclosed method for manufacturing an organic EL device, which comprises a step of forming an anode on a substrate; a step of forming a hole injection layer on the anode; a step of forming an inorganic film on the substrate and the hole injection layer; a step of forming a bank on the inorganic film in such a manner that at least a part of the inorganic film formed on the hole injection layer is exposed; a step of etching the exposed inorganic film by using the bank as a mask so that the hole injection layer is exposed therefrom; and a step of forming an organic light-emitting layer by applying an organic light-emitting material onto the exposed hole injection layer. The hole injection layer contains tungsten oxide or molybdenum oxide.