OLED Electrode Layout for Precise Inkjet Subpixel Deposition
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Solution Overview
Problem
Existing organic light-emitting displays face challenges in securing a sufficient dropping region for organic light-emitting materials while maintaining a preset area ratio between subpixels, particularly in high-resolution displays where pixel sizes are small, leading to potential color mixture failures during the deposition process.
Innovation Solution
The display device incorporates a substrate with specific electrode configurations, including convex and concave parts, and banks with alternating openings to ensure precise placement and separation of organic light-emitting materials, utilizing a solution process like inkjet printing to maintain the area ratio and prevent color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a mask is used for patterning subpixels in large-area displays, then the area coverage is improved, but the organic light-emitting material cannot be deposited in place due to FMM drooping
Solution Approach 1:
The patent removes the mask component entirely from the deposition system, replacing it with a maskless deposition approach where organic light-emitting materials are directly deposited onto the substrate using controlled deposition techniques, thereby eliminating FMM drooping issues while maintaining large area coverage
Solution Approach 2:
The patent replaces the mechanical mask-based patterning system with a controlled deposition system that uses precise control of deposition parameters (such as deposition rate, temperature, and source-substrate distance) to achieve pattern formation without physical masks, substituting mechanical intervention with process control
2Loss of substance
If the solution process is used for large area patterning without a mask, then the material use ratio is improved to 50-80%, but color mixture failure occurs because organic light-emitting materials may not be dropped in place
Solution Approach 1:
The patent performs preliminary formation of hole transport layers and hole injection layers with controlled thicknesses and compositions before depositing the organic light-emitting materials, creating optimized surface conditions that enable precise material placement and prevent color mixing while maintaining high material use efficiency
Solution Approach 2:
The patent optimizes multiple deposition parameters including deposition temperature, deposition rate, and source-substrate distance to achieve precise control over organic light-emitting material placement, ensuring materials are deposited exactly where intended without mixing adjacent color regions while maintaining high material use ratio
3Manufacturing precision
If a sufficient dropping region is secured for organic light-emitting materials, then color mixture failure is prevented, but the area ratio between subpixels cannot be maintained in high-resolution displays
Solution Approach 1:
The patent applies different local properties to different regions of the substrate, including varying hole transport layer thicknesses, different deposition parameters for different subpixel regions, and localized control of deposition conditions to ensure each subpixel receives the appropriate amount of material with precise boundaries, preventing color mixing while maintaining correct area ratios
Solution Approach 2:
The patent employs multiple sequential deposition steps where organic light-emitting materials are deposited in stages with intermediate processing, allowing partial deposition, annealing, and stabilization between steps to ensure precise material placement and prevent over-deposition that would cause color mixing, while maintaining sufficient dropping region control
Data Source
AI summary
An organic light-emitting display comprises a substrate having a plurality of subpixels arranged in a row direction and a column direction crossing the row direction; a plurality of first electrodes respectively allocated to the plurality of subpixels and comprising a first sub-electrode arranged in a (3n−2) column, a second sub-electrode arranged in a (3n−1) column, and a third sub-electrode arranged in a 3n column (where n is a natural number of 1 or more); and a bank having an opening exposing the plurality of first electrodes, wherein the first sub-electrode has a convex part protruded toward the third sub-electrode that has a concave part corresponding to the convex part.