Secondary Electrode Reduces Cathode Resistance in OLED Panels
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Solution Overview
Problem
Top-emitting type OLED devices face issues with large voltage drops due to the high resistance of the cathode, which can damage the display panel, especially in larger devices.
Innovation Solution
An organic electroluminescent display panel design that includes a secondary electrode on the packaging film electrically connected to the cathode through a via hole, increasing the equivalent thickness of the cathode and reducing its resistance, thereby mitigating the voltage drop problem.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin layer of metal is formed as the cathode by using a vapor deposition process, then the light emitting layer is protected from damage, but the cathode resistance increases causing large voltage drop
Solution Approach 1:
The patent introduces a secondary electrode positioned on the packaging film side, creating a new spatial dimension for electrical connection. This secondary electrode connects to the cathode through a via hole, forming a distributed electrode structure that reduces resistance without compromising the thin cathode layer's protective function.
Solution Approach 2:
The cathode function is segmented into two parts: the thin metal layer on the light emitting layer side provides protection, while the secondary electrode on the packaging film side provides low-resistance electrical connection. This segmentation allows each component to optimize its specific function.
2Illumination intensity
If a transparent conductive oxide film is formed as the cathode by using a magnetron sputtering process, then light transmission is improved, but the light emitting layer is damaged
Solution Approach 1:
The thin metal cathode layer acts as an intermediary between the light emitting layer and the secondary electrode. It provides mechanical protection to the light emitting layer while the secondary electrode compensates for its higher resistance through the additional electrical connection path.
Data Source
AI summary
The present invention discloses an organic electroluminescent display panel, comprising: a base substrate; a top-emitting type organic electroluminescent structure located on the base substrate, the organic electroluminescent structure comprising an anode, a light emitting layer and a cathode arranged in this order from the base substrate; and a packaging film covering the organic electroluminescent structure; the organic electroluminescent display panel further comprises a secondary electrode provided on the packaging film and electrically connected with the cathode through a via hole penetrating through the packaging film. Since the secondary electrode is additionally provided on the packaging film and is electrically connected with the cathode through the via hole penetrating through the packaging film, the secondary electrode electrically connected with the cathode can increase an equivalent thickness of the cathode and thus reduce the resistance of the cathode, which can avoid the problem of large voltage drop due to large resistance of the cathode when a thinner metal is used as the cathode, thereby can avoid damage of the organic electroluminescent display panel due to the larger voltage drop.