Organic EL Display Patterning via Water-Soluble Mask
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Solution Overview
Problem
Current methods for manufacturing organic electroluminescence (EL) display devices face challenges such as limited pixel size due to the use of fine metal masks, material compatibility issues with photolithography, and water-solubility problems with alkali metal compounds, which hinder the production of high-definition and large-format displays.
Innovation Solution
A method involving the formation of a water-insoluble organic compound layer between electrodes, use of a mask layer with a water-soluble material for patterning, and subsequent removal of the mask layer followed by the deposition of an alkali metal or alkaline-earth metal layer, eliminating the need for fine metal masks and addressing material solubility issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fine metal mask is used for vapor deposition patterning, then manufacturing precision of organic compound layer is improved, but device complexity and manufacturing cost increase due to mask cleaning and maintenance
Solution Approach 1:
The invention extracts and removes the metal mask from the manufacturing process entirely. Instead of using a metal mask for vapor deposition patterning, the patent forms the organic compound layer over the entire substrate and then selectively removes it in non-pixel regions through wet etching, thereby eliminating mask-related complexity and costs while maintaining patterning precision
Solution Approach 2:
The invention inverts the conventional patterning approach. Rather than forming the organic compound layer only in pixel regions from the beginning using a mask, the patent forms it everywhere and then removes it from non-pixel regions. This inversion eliminates the need for metal masks and their associated maintenance issues
2Manufacturing precision
If photolithography is used for patterning organic compound layer, then manufacturing precision is improved, but material compatibility problems arise due to solvent dissolution
Solution Approach 1:
The invention changes the solubility parameter of the organic compound layer by selecting materials that are insoluble in water but soluble in organic solvents. This allows the use of water-based photoresist and developer solutions in photolithography without dissolving the organic compound layer, thereby resolving material compatibility issues while maintaining high patterning precision
Solution Approach 2:
The invention applies different solubility characteristics to different parts of the material system. The organic compound layer is designed to be insoluble in water (resistant to water-based photoresist), while the photoresist itself is soluble in organic solvents for removal. This localized differentiation of solubility properties enables compatible material selection
3Power
If alkali metal compound is used in electron injection layer, then electron injection efficiency is improved, but reliability decreases due to water solubility
Solution Approach 1:
The invention performs preliminary protective action by forming a waterproof encapsulation layer over the organic compound layer and electron injection layer before they are exposed to water. This preliminary protection prevents water from reaching and dissolving the alkali metal compound, thereby maintaining both electron injection efficiency and reliability
Solution Approach 2:
The invention introduces a waterproof encapsulation layer as an intermediary between the water environment and the alkali metal compound. This intermediary layer blocks water from contacting the water-soluble alkali metal compound while allowing the compound to maintain its electron injection function, thus resolving the reliability issue without sacrificing efficiency
4Measurement precision
If pixel size is reduced for high definition, then measurement precision is improved, but manufacturing precision becomes more difficult to maintain with metal masks
Solution Approach 1:
The invention extracts the metal mask from the process, eliminating the physical limitations of mask opening fineness. Without a metal mask, there is no minimum opening size constraint, allowing pixel sizes to be reduced to achieve high definition while maintaining manufacturing precision through alternative patterning methods
Solution Approach 2:
The invention replaces the mechanical metal mask system with a chemical patterning approach using photolithography and wet etching. This substitution removes the mechanical constraints of mask thickness and opening size, enabling finer pixel definitions while maintaining manufacturing precision through chemical process control
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 enables the production of high-definition organic EL display devices with pixel sizes as small as 10 μm and supports large-format displays, while maintaining the electron injection characteristics and reducing manufacturing costs.
Implementation Method 1
an organic compound layer which is a component of the element is a thin film layer formed by forming a thin film made of an organic material by vapor deposition
Implementation Method 2
a photoresist pattern forming step of forming a photoresist pattern on the mask layer; a mask layer forming step of forming a mask layer in a region where the photoresist pattern is not formed
Implementation Method 3
an organic compound layer is patterned by wet etching
Data Source
AI summary
A method of manufacturing an organic electroluminescence display device includes an organic compound layer which is placed between a pair of electrodes and includes at least an emission layer, the organic compound layer being two-dimensionally arranged, includes forming the organic compound layer which is insoluble in water in an entire emission region on a substrate, providing a mask layer containing a water-soluble material in at least a part of a region on the organic compound layer, removing a part of the organic compound layer which is provided in a region which is other than the region in which the mask layer is provided, removing the mask layer, and forming, after the removing of the mask layer, a layer containing at least an alkali metal or an alkaline-earth metal in a region including at least the emission region.