Top-Emitting OLED Panel Layout for Uniform Brightness
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Solution Overview
Problem
Top emitting OLED display devices face challenges in achieving uniform brightness due to high surface resistance and voltage drop in transparent cathodes, and existing manufacturing methods are inefficient and prone to defects such as wrinkles and alignment issues during the production of auxiliary electrodes and pixel defining layers.
Innovation Solution
A display panel design where the first electrode and auxiliary layer are disposed on the same side of the backplane with a pixel defining layer and auxiliary electrode positioned to reduce resistance and voltage drop, and a manufacturing method that forms these layers with specific structural features to enhance production efficiency and prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transparent cathodes are used in top emitting OLED display devices, then the devices achieve self-luminescence and high luminous efficiency, but the high surface resistance and voltage drop cause non-uniform brightness
Solution Approach 1:
The cathode is segmented into a main electrode and an auxiliary electrode. The main electrode provides the primary current path, while the auxiliary electrode, positioned within the pixel defining layer projection, provides additional current distribution to specific regions. This segmentation allows optimization of current density distribution across the pixel, compensating for voltage drops and improving brightness uniformity without requiring the entire cathode to have uniformly low resistance.
2Productivity
If existing manufacturing methods are used to produce auxiliary electrodes and pixel defining layers, then the devices can be manufactured, but the process is inefficient and prone to defects such as wrinkles and alignment issues
Solution Approach 1:
The auxiliary electrode and pixel defining layer are merged into a single patterning step. By forming both structures simultaneously from the same patterned layer, the invention eliminates separate alignment processes, thereby improving manufacturing efficiency and eliminating alignment errors between the two components. This merging approach also prevents wrinkles that may occur during separate handling and deposition processes.
3Reliability
If the auxiliary electrode is positioned outside the pixel defining layer projection, then the manufacturing process is simpler, but the resistance reduction and voltage drop mitigation are insufficient
Solution Approach 1:
The auxiliary electrode is nested within the projection area of the pixel defining layer, specifically positioned between the first electrode and the second electrode in the vertical stacking direction. This nesting arrangement allows the auxiliary electrode to effectively intercept and redistribute current in the high-resistance regions without adding lateral complexity to the device structure. The auxiliary electrode's projection is contained within the pixel defining layer's projection, maintaining a compact and integrated structure while achieving superior electrical performance.
Data Source
AI summary
Provided is a display panel, including: a backplane; a first electrode and an auxiliary layer, disposed on a same side of the backplane, wherein a distance between a surface of the first electrode distal from the backplane and the backplane is shorter than or equal to a distance between a surface of the auxiliary layer distal from the backplane and the backplane; a pixel defining layer, at least partially disposed on a side of the auxiliary layer distal from the backplane; a second electrode, disposed on a side of the pixel defining layer distal from the backplane; and an auxiliary electrode, disposed on a side of the second electrode distal from the backplane, wherein an orthographic projection of the auxiliary electrode onto the backplane is located within an orthographic projection of the pixel defining layer onto the backplane.