Organic EL Display Patterning via Soluble Release Layer
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Solution Overview
Problem
Conventional methods for manufacturing organic electroluminescence (EL) display devices using photolithography result in inferior element characteristics due to residual insulative layers and diffusion of impurities, limiting pixel size and accuracy, especially for large-format displays.
Innovation Solution
A method involving the formation of an organic compound layer, a release layer made of a charge-transportable organic compound soluble in a polar solvent, and selective removal techniques to pattern the release layer, allowing for precise patterning without the need for metal masks, thereby achieving element characteristics comparable to those formed with vacuum in-situ processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If photolithography is used to pattern the organic compound layer, then the manufacturing process becomes more versatile and suitable for large-format displays, but residual insulative layers remain on the emission layer surface deteriorating element characteristics
Solution Approach 1:
A water-soluble polymer layer is introduced as an intermediary between the organic compound layer and the photoresist. This intermediate layer enables photolithography processing while preventing direct contact between the photoresist and the organic compound layer, thus avoiding contamination and crystallization issues that would deteriorate element characteristics.
Solution Approach 2:
The patent segments the manufacturing process into distinct stages: forming the organic compound layer, adding the water-soluble polymer layer, applying the photoresist, performing photolithography, and finally removing the water-soluble polymer layer. This segmentation allows each layer to serve its specific function without interfering with others, resolving the contradiction between process versatility and element quality.
2Manufacturing precision
If a fine metal mask is used for vapor deposition patterning, then manufacturing precision is improved, but the mask requires frequent cleaning and has limited reuse, increasing manufacturing cost
Solution Approach 1:
The patent replaces the mechanical metal mask system with a photolithography-based patterning system. Instead of using a physical mask that requires cleaning and maintenance, the invention uses a photoresist layer guided by a mask for optical patterning, followed by chemical etching. This substitution eliminates the need for repeated mask cleaning and reduces manufacturing costs while maintaining fine patterning capability.
3Manufacturing precision
If the pixel size is reduced below 100 μm, then display fineness is improved, but the mask positional accuracy becomes difficult to secure, worsening manufacturing precision
Solution Approach 1:
The patent uses a photomask to create an optical pattern that is copied onto the photoresist layer through photolithography. This optical copying method allows for precise pattern transfer at sub-100 μm scales without requiring the physical mask to maintain positional accuracy during vapor deposition, as the pattern is transferred optically rather than mechanically.
4Ease of manufacture
If a water-soluble polymer is used as a release layer, then the organic compound layer can be patterned by photolithography, but the polymer layer serves as resistance and deteriorates element characteristics
Solution Approach 1:
The water-soluble polymer layer is applied as a preliminary protective layer during the photolithography process. After the patterning is complete, this layer is completely removed by water washing before the organic compound layer is patterned. This preliminary action enables easy patterning while ensuring no residue remains to affect element characteristics.
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 enables the production of organic EL display devices with improved element characteristics and finer pixel sizes, suitable for large-format displays, by selectively removing the release layer without damaging the organic compound layer, thus enhancing manufacturing efficiency and accuracy.
Implementation Method 1
the release layer includes a deposited film formed of a charge-transportable organic compound, and is soluble in a polar solvent
Implementation Method 2
an organic compound layer in the element is a thin film layer formed by forming a thin film made of an organic material by vapor deposition
Data Source
AI summary
Provided is a method of manufacturing an organic electroluminescence display device including: an organic compound layer-forming step of forming an organic compound layer on a first electrode; a release layer-forming step of forming a release layer on the organic compound layer; a first processing step for the release layer of patterning the release layer; an organic compound layer-processing step of removing the organic compound layer in a region not covered with the release layer processed in the first processing step for the release layer; and a second processing step for the release layer of removing a part of the release layer, in which the release layer is a deposited film formed of a charge-transportable organic compound and is dissolved by a solvent containing an organic solvent miscible with water.