Inkjet Color Conversion Layer for Organic EL Displays
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Solution Overview
Problem
Existing methods for manufacturing color conversion layers in organic EL displays face challenges such as concentration quenching, high film thickness requirements, and limitations in achieving high-resolution patterns due to the need for separate barrier walls and metal masks, which increase manufacturing costs and complexity.
Innovation Solution
A method involving the formation of a black matrix with openings on a transparent substrate, followed by independently forming multiple color filter layers that transmit different wavelengths, and using an inkjet method to create a color conversion layer without separate barrier walls, allowing for high-resolution patterns and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the concentration of color conversion material is raised to increase absorptance and converted light intensity, then light conversion efficiency is improved, but concentration quenching occurs causing energy loss without light emission
Solution Approach 1:
The invention divides the color conversion layer into multiple sub-layers, each containing a different color conversion material with specific absorption characteristics. This segmentation allows each sub-layer to operate at optimized material concentrations without excessive quenching, while collectively achieving high overall absorptance across the target wavelength range.
Solution Approach 2:
Different color conversion materials are distributed at different locations within the color conversion layer structure. Each material is placed in a specific sub-layer where its absorption characteristics best match the incident light spectrum, enabling localized optimization of conversion efficiency while maintaining appropriate material concentrations to avoid quenching.
2Use of energy by moving object
If the film thickness of the color conversion layer is increased to raise absorptance and maintain color conversion efficiency, then light absorption is improved, but manufacturing complexity increases due to breakage of electrode patterns and difficulty in achieving high resolution
Solution Approach 1:
The color conversion layer is divided into multiple thin sub-layers rather than forming a single thick layer. This segmentation reduces the film thickness of each individual sub-layer to a manageable range that avoids electrode pattern breakage and enables high-resolution manufacturing, while the cumulative thickness of all sub-layers maintains sufficient light absorption efficiency.
3Manufacturing precision
If separate barrier walls are formed to enable inkjet patterning of color conversion layers, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention merges the barrier wall function with the color filter layer by forming the color filter layer to extend beyond the opening boundaries and overlap with adjacent color filter layers. This integration eliminates the need for separate barrier wall structures while maintaining effective inkjet patterning precision, as the overlapping color filter layers themselves serve as the containment barriers.
Solution Approach 2:
The color filter layer is designed to perform multiple functions: it provides color filtering, serves as a barrier wall for inkjet patterning, and creates the structural framework for the color conversion layer formation. This multi-functionality reduces the total number of separate components and manufacturing steps while maintaining manufacturing precision.
4Manufacturing precision
If metal masks are used for evaporation deposition to form color conversion layers, then manufacturing precision is improved, but device complexity and manufacturing cost increase due to mask fabrication and handling
Solution Approach 1:
The invention replaces the mechanical mask-based evaporation deposition system with an inkjet printing system. Instead of using physical metal masks that require fabrication, alignment, and handling, the color conversion layers are directly patterned onto the substrate using inkjet deposition, eliminating the entire mask subsystem and its associated complexity.
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 formation of high-resolution color conversion layers with adequate light intensity and reduced manufacturing costs, overcoming the limitations of previous methods by eliminating the need for separate barrier walls and using the black matrix as a positioning marker for inkjet patterning.
Implementation Method 1
a color conversion layer which absorbs light of a specific wavelength, and outputs light comprising a wavelength different from the absorbed wavelength
Implementation Method 2
a fluorescent conversion layer (equivalent to a color conversion layer) which performs conversion into light of a prescribed wavelength
Implementation Method 3
a method in which a liquid comprising a color conversion material dispersed in a resin is applied
Data Source
AI summary
A process for producing a color conversion filter uses an ink jet recording method, which can form a color conversion layer at a desired position without the need to separately form partition walls, and a process for producing an organic EL display. The process for producing a color conversion filter includes forming a black matrix having a plurality of opening parts on a transparent substrate, forming at least two types of color filter layers independently of each other on a black matrix to which dissimilar color filter layers are adjacent, to form a partition wall, at least two of the color filter layers being superimposed on top of each other, and forming a color conversion layer by ink jet recording onto at least one of the color filter layers.