Top-Emitting OLED Cathode Groove Structure for Uniform Voltage
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Solution Overview
Problem
Top-emitting OLED display panels face issues with high resistance and significant voltage drop in the cathode layer, leading to uneven light emission due to the distance from the power supply, and the organic light-emitting layer often adheres to the auxiliary electrode during formation, disrupting electrical connections.
Innovation Solution
A display panel design featuring a substrate with a pixel-defining layer, a conductive pattern including an auxiliary electrode layer with a groove in its side wall, and a cathode layer that extends into the groove, ensuring effective overlapping and uniform voltage distribution across the cathode layer, preventing the light-emitting layer from adhering to the auxiliary electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cathode layer is formed as a continuous flat layer, then the manufacturing process is simple, but the voltage distribution is uneven and resistance is high due to distance from power supply
Solution Approach 1:
The cathode layer is segmented into multiple parts: a first cathode layer in the pixel region and a second cathode layer in the non-pixel region that extends into the groove. This segmentation allows different regions to serve different functions - the first cathode layer provides uniform voltage for light emission while the second cathode layer in the groove provides additional electrical connection and voltage stabilization, resolving the contradiction between manufacturing simplicity and voltage distribution uniformity
Solution Approach 2:
The second cathode layer extends into the groove in the depth dimension (z-direction), creating a three-dimensional electrical connection structure. This dimensional change allows the cathode to access the auxiliary electrode through the groove, providing multiple electrical connection paths and improving voltage distribution uniformity without complicating the overall manufacturing process
2Productivity
If the light-emitting layer is formed by evaporation, then the formation process is efficient, but the light-emitting layer adheres to the auxiliary electrode, disrupting electrical connections
Solution Approach 1:
The groove structure extracts or removes the problematic direct contact area between the light-emitting layer and auxiliary electrode. By creating a physical separation through the groove, the design prevents the light-emitting layer from adhering to the auxiliary electrode during evaporation, while still maintaining electrical connection through the second cathode layer that extends into the groove
Solution Approach 2:
The second cathode layer acts as an intermediary between the auxiliary electrode and the rest of the cathode structure. It extends into the groove to provide electrical connection to the auxiliary electrode while preventing the light-emitting layer from directly contacting and adhering to the auxiliary electrode, thus maintaining electrical connection integrity without sacrificing formation efficiency
Data Source
AI summary
A display panel includes: a substrate, a pixel-defining layer disposed on the substrate, and a conductive pattern, a light-emitting layer and a cathode layer which are laminated in a direction perpendicular to and away from the substrate. The pixel-defining layer is configured to define a plurality of pixel regions and a non-pixel region outside the pixel regions on the substrate. The conductive pattern includes: an auxiliary electrode layer disposed in the non-pixel region, wherein a groove is formed in a side wall of the auxiliary electrode layer. The cathode layer includes: a first portion disposed in the pixel region and a second portion disposed in the non-pixel region. The second portion of the cathode layer extends into the groove and is in contact with the groove.