Non-uniform Cathode Thickness in OLED Displays
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Solution Overview
Problem
Organic light-emitting display apparatuses face issues with moisture degradation of organic light-emitting elements and light-emitting efficiency due to cathode thickness and foreign substances causing short circuits in top emission schemes.
Innovation Solution
The solution involves forming a barrier pattern with a fluoropolymer containing a large amount of fluorine on the organic light-emitting elements and varying the thickness of the cathode electrode in sub-pixels, particularly making the cathode in the green sub-pixel thicker to enhance light-emitting efficiency and prevent moisture invasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the common cathode is made thick to prevent short circuits, then reliability is improved, but light transmittance is reduced, causing light-emitting efficiency to deteriorate
Solution Approach 1:
The patent applies local quality by making the cathode electrode thickness non-uniform across different sub-pixels. Specifically, the green sub-pixel has a thicker cathode electrode (500-1000 nm) to prevent short circuits, while other sub-pixels have thinner cathode electrodes (100-300 nm) to maintain high light transmittance and efficiency. This localized differentiation resolves the contradiction between reliability and light-emitting efficiency.
2Reliability
If the common cathode is made thick to prevent short circuits, then reliability is improved, but device complexity increases due to varying thickness requirements
Solution Approach 1:
The patent implements local quality by differentiating cathode electrode thickness across specific sub-pixels. The green sub-pixel receives a thicker cathode layer (500-1000 nm) while other sub-pixels maintain thinner layers (100-300 nm), achieving reliability improvement without requiring complete redesign of the entire cathode structure.
Solution Approach 2:
The patent applies parameter changes by modifying the thickness parameter of the cathode electrode in specific regions. By changing the thickness from 100-300 nm in most sub-pixels to 500-1000 nm in the green sub-pixel, the patent achieves short circuit prevention while maintaining overall structural simplicity and manufacturability.
3Reliability
If barrier patterns are added to prevent moisture invasion, then reliability is improved, but device complexity and manufacturing complexity increase
Solution Approach 1:
The patent introduces barrier patterns as intermediary structures between the cathode electrode and the external environment. These barrier patterns, formed by depositing materials such as aluminum oxide, aluminum nitride, or silicon oxide, act as mediators that block moisture penetration paths without requiring fundamental changes to the existing manufacturing processes.
Solution Approach 2:
The patent employs composite material structures by combining the cathode electrode material with barrier material layers. The barrier patterns are formed as separate layers (e.g., aluminum oxide, aluminum nitride, silicon oxide) deposited on top of or integrated with the cathode electrode, creating a composite structure that provides both electrical functionality and moisture protection.
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 effectively prevents moisture invasion, improves light-emitting efficiency, and reduces the risk of short circuits by optimizing cathode thickness and using a fluoropolymer barrier pattern, thereby extending the lifespan and performance of the organic light-emitting display apparatus.
Implementation Method 1
a barrier pattern with a fluoropolymer containing a large amount of fluorine
Implementation Method 2
an organic light-emitting element including an anode electrode, an organic light-emitting layer disposed on the anode electrode, and a cathode electrode disposed on the organic light-emitting layer
Data Source
AI summary
The present disclosure provides an organic light-emitting display apparatus and method for manufacturing the same. The organic light-emitting display apparatus includes a pixel including a first sub-pixel, a second sub-pixel, a third sub-pixel and a fourth sub-pixel; wherein each of the first to fourth sub-pixels includes an organic light-emitting element including an anode electrode, an organic light-emitting layer disposed on the anode electrode, and a cathode electrode disposed on the organic light-emitting layer, wherein a thickness of the cathode electrode disposed in the fourth sub-pixel is larger than a thickness of the cathode electrode disposed in each of the first to third sub-pixels.