OLED Insulating Part Prevents Foreign Material Short Circuits
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Solution Overview
Problem
In active matrix organic light emitting display devices, foreign materials can cause short circuits between the pixel electrode and the common electrode, leading to defective pixels that cannot emit light, due to the penetration of metal oxide layers into gaps between foreign particles and the conductive organic layer, resulting in reduced luminance and increased resistance.
Innovation Solution
An organic light emitting display device is designed with an insulating part formed on the surface of the metal layer exposed to foreign materials, preventing short circuits by isolating the pixel electrode from the common electrode, and a conductive organic layer is used to prevent the metal oxide layer from penetrating into gaps, while an auxiliary electrode is connected to the common electrode to manage voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a metal oxide layer is used to connect the common electrode to the auxiliary electrode, then the step coverage is improved, but the foreign material penetration increases causing short circuits
Solution Approach 1:
The patent employs a composite electrode structure consisting of multiple layers including a first electrode, a second electrode, and a third electrode with different material compositions. This composite structure provides both adequate step coverage and prevents foreign material penetration by creating multiple barriers, thus resolving the contradiction between shape quality and reliability.
Solution Approach 2:
The electrode connection structure is divided into multiple segmented layers (first electrode, second electrode, third electrode) rather than using a single metal oxide layer. Each layer serves a specific function: providing step coverage, blocking foreign materials, and ensuring electrical connectivity. This segmentation allows simultaneous achievement of good step coverage and short circuit prevention.
2Reliability
If the common electrode is formed with a metal layer and conductive organic layer, then the electrical conductivity is improved, but the resistance in the central portion increases reducing luminance
Solution Approach 1:
The patent introduces auxiliary electrodes positioned at specific locations (central portion and peripheral portion) to create additional current paths in different spatial dimensions. This multi-dimensional electrode arrangement reduces the resistance in the central portion by providing alternative current flow paths, thereby maintaining luminance while preserving the conductive properties of the common electrode.
3Reliability
If foreign materials are present during OLED formation, then manufacturing defects increase, but adding insulating parts increases device complexity
Solution Approach 1:
The insulating function is merged into the existing multi-layer electrode structure rather than being added as a separate independent component. The third electrode layer serves dual purposes: providing electrical connectivity and acting as an insulating barrier against foreign material penetration. This merging approach prevents defects while minimizing additional structural complexity.
Data Source
AI summary
Disclosed is an organic light emitting display device. The organic light emitting display device includes a substrate, a pixel electrode disposed on the substrate, an organic emission layer disposed on the pixel electrode, a common electrode including a metal layer disposed on the organic emission layer, a conductive organic layer disposed on the metal layer, and a first metal oxide layer disposed on the conductive organic layer, and an insulating part formed in a part of an area of a surface of the metal layer which is exposed to a foreign material. The insulating part insulates the pixel electrode from the common electrode.