Staggered Organic EL Display Cathode Uniformity
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Solution Overview
Problem
Organic electro-luminescence display panels face degradation due to uneven thickness of the cathode on the sides of the common layers, leading to varying resistance and performance issues.
Innovation Solution
The organic electro-luminescence display panel features a staggered arrangement of common layers forming a stair shape, with each layer positioned to ensure even thickness of the second electrode, preventing degradation by maintaining consistent resistance across the panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the cathode is deposited on the substrate including the common layers stacked at the same position, then the front surface of the cathode has flat uniform thickness, but the side surfaces of the cathode have non-uniform thickness due to step coverage, leading to varying resistance and degradation
Solution Approach 1:
The patent transitions from a single-plane stacking arrangement to a multi-level staggered stacking arrangement, where common layers are positioned at different heights (side surfaces) rather than all at the same position. This dimensional change eliminates the step coverage effect that causes non-uniform cathode thickness, as the cathode can now be deposited at a uniform thickness across the entire surface without encountering height differences between layers.
Solution Approach 2:
The patent introduces asymmetric positioning of common layers, where layers are staggered relative to each other rather than being symmetrically aligned at the same position. This asymmetric arrangement creates a gradual transition in height across the structure, allowing the cathode to be deposited uniformly without the sharp steps that would occur with symmetric alignment, thereby preventing varying resistance and degradation.
2Ease of manufacture
If common layers are stacked at the same position, then the structure is simple and easy to manufacture, but the cathode thickness becomes non-uniform at side surfaces causing performance degradation
Solution Approach 1:
The patent resolves the manufacturing complexity by moving the stacking arrangement into a multi-dimensional space rather than confining all layers to a single plane. The staggered arrangement along side surfaces creates a three-dimensional structure that is still manufacturable using standard deposition techniques, while achieving uniform cathode thickness that would be impossible with single-plane stacking.
3Productivity
If the cathode has varying thickness at different positions, then deposition is simpler, but resistance varies across the panel leading to degradation
Solution Approach 1:
The patent performs a preliminary action by arranging common layers in a staggered configuration before cathode deposition. This pre-arrangement creates a surface topology that is optimized for uniform cathode deposition, eliminating the need for complex deposition control mechanisms and ensuring consistent thickness without sacrificing deposition efficiency. The preliminary structural preparation prevents the need for post-deposition corrections.
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
The staggered arrangement of common layers ensures even deposition of the cathode, eliminating degradation and enhancing the panel's lifetime and brightness by maintaining consistent resistance.
Implementation Method 1
the plurality of organic common layers are formed using a shadow mask
Data Source
AI summary
An organic electro-luminescence display panel and a method for fabricating the same is described which can prevent the display panel from degrading. The organic electro-luminescence display panel includes a drive thin film transistor formed on a substrate, a first electrode connected to the drive thin film transistor, a bank insulating film having a bank hole formed therein for exposing the first electrode, organic common layers having a plurality of common layers stacked in the bank hole, and a second electrode formed on the organic common layers, wherein the plurality of organic common layers are have stacked positions different from one another such that their side edges form a stair shape on both sides.