Auxiliary Cathode Electrode Layout for Uniform Large-Area Displays
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Solution Overview
Problem
In large area displays, the high resistance of cathode electrodes made of transparent conductive materials leads to voltage drops (IR drops), resulting in luminance non-uniformity.
Innovation Solution
The display device incorporates an auxiliary electrode with an opening and a groove at its edge, allowing direct contact with a second electrode, and an insulation film with a curved cross-section to facilitate contact between these electrodes, preventing voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a transparent conductive material is used for the cathode electrode in a large area display, then the display can be manufactured with standard materials, but voltage drops (IR drops) occur due to high resistance, resulting in luminance non-uniformity
Solution Approach 1:
The cathode electrode is divided into a first electrode and an auxiliary electrode. The auxiliary electrode includes an opening that allows direct contact with the anode (second electrode), creating multiple current paths and reducing overall resistance. This segmentation resolves the high resistance issue in large area displays while maintaining luminance uniformity.
Solution Approach 2:
The opening in the auxiliary electrode acts as an intermediary structure that enables direct contact between the auxiliary electrode and the anode. This intermediate contact point creates an additional current path that bypasses the high resistance path through the transparent conductive material, reducing voltage drops and improving luminance uniformity.
2Reliability
If the auxiliary electrode and second electrode are brought into direct contact, then voltage drops are prevented, but the structural complexity increases due to the opening and groove configuration
Solution Approach 1:
The auxiliary electrode includes an opening that extends in the vertical dimension, allowing the anode to contact the auxiliary electrode from above. This three-dimensional configuration enables direct contact between electrodes without adding horizontal complexity, resolving the voltage consistency issue while minimizing structural complexity.
3Reliability
If the emission layer is positioned to overlap the opening of the auxiliary electrode, then direct contact between auxiliary electrode and anode is enabled, but the emission layer may contact the auxiliary electrode causing short circuits
Solution Approach 1:
The emission layer is positioned to overlap the opening of the auxiliary electrode in the planar direction, but the opening extends vertically to allow the anode to contact the auxiliary electrode. This local differentiation in spatial positioning ensures proper electrode contact while preventing emission layer contact with the auxiliary electrode, eliminating short circuit risks.
Data Source
AI summary
A display device includes a substrate; a transistor disposed on the substrate; a first electrode connected to the transistor; an auxiliary electrode disposed on the same layer as the first electrode; an emission layer disposed on the first electrode; and a second electrode disposed on the emission layer, wherein the auxiliary electrode includes an opening, and a side surface of the auxiliary electrode and the second electrode are in direct contact at the opening of the auxiliary electrode.