OLED Display Panel Cathode Connection for Low Resistance
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Solution Overview
Problem
The preparation process of the auxiliary electrode and its connection to the cathode layer in top-emitting OLED display panels is complex, leading to increased square resistance and complicating the manufacturing process due to the thinness of the cathode layer made of Mg/Ag alloy.
Innovation Solution
A display panel design featuring a base substrate with an auxiliary electrode in the non-display area, a passivation layer with openings that form an accommodating space exposing the auxiliary electrode, and a cathode layer with a connecting portion electrically connected to the auxiliary electrode, allowing for directional deposition of the cathode material by applying a voltage and using a charged evaporation method to reduce cathode resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the cathode layer is made very thin to ensure transmittance, then the transmittance is improved, but the square resistance of the cathode layer increases
Solution Approach 1:
The cathode system is segmented into two parts: a thin cathode layer (for transmittance) and a separate auxiliary electrode (for conductivity). The cathode layer is made thin to ensure light transmittance, while the auxiliary electrode is added specifically to compensate for the increased square resistance, resolving the contradiction between transmittance and electrical conductivity.
Solution Approach 2:
The accommodating space acts as an intermediary structure that enables direct electrical connection between the cathode layer and the auxiliary electrode. This mediator structure allows the thin cathode layer to maintain low square resistance through the auxiliary electrode without compromising its thinness and transmittance properties.
2Reliability
If an auxiliary electrode is added to reduce the square resistance of the cathode layer, then the square resistance is improved, but the preparation process and connection process become complicated
Solution Approach 1:
The auxiliary electrode is merged with the cathode layer formation process by using the same vacuum evaporation equipment and process. The accommodating space is integrated into the passivation layer structure, allowing both the auxiliary electrode and cathode layer to be formed in one continuous process, thereby simplifying the overall preparation process despite adding functional complexity.
Solution Approach 2:
The auxiliary electrode serves multiple functions: it reduces square resistance, provides electrical connection, and can be formed using the same evaporation process as the cathode layer. The accommodating space serves both as a connection channel and as part of the passivation layer structure, demonstrating multi-functionality that reduces overall process complexity.
3Reliability
If an auxiliary electrode is added to reduce the square resistance of the cathode layer, then the square resistance is improved, but new equipment or processes are required
Solution Approach 1:
The auxiliary electrode is formed using the same vacuum evaporation equipment and process that is already used for depositing the cathode layer and other metal layers in OLED manufacturing. This universal approach allows the auxiliary electrode to be added without requiring new equipment, maintaining ease of manufacture while improving square resistance.
Solution Approach 2:
The auxiliary electrode uses the same Mg/Ag alloy material as the cathode layer, with the same composition parameters (90:10 or 80:20 ratio). By using identical material parameters and formation processes, the auxiliary electrode can be integrated into the existing manufacturing workflow without requiring new equipment or process changes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design simplifies the manufacturing process by reducing cathode resistance without adding new equipment or processes, ensuring a complete and functional cathode layer connection with the auxiliary electrode, thereby improving the OLED display panel's performance.
Implementation Method 1
applying a voltage to the auxiliary electrode; and evaporating a cathode material on the passivation layer; the cathode material carries charges that are electrically opposite to the voltage applied to the auxiliary electrode; and the cathode material, when being evaporated, is attracted to the accommodating space by the auxiliary electrode
Data Source
AI summary
Disclosed in embodiments of the present disclosure are a display panel, a preparation method thereof, and a display device. A display panel having a display area and a non-display area includes: a base substrate; an auxiliary electrode in the non-display area; a passivation layer disposed on a side of the auxiliary electrode facing away from the base substrate, having a first opening in the non-display area, in the first opening, an accommodating space is formed between the passivation layer and the auxiliary electrode, the accommodating space exposes part of the auxiliary electrode; an orthographic projection of the passivation layer on the base substrate covers an orthographic projection of the accommodating space on the base substrate; a cathode layer disposed on a side of the passivation layer facing away from the base substrate, having a connecting portion in the accommodating space, the connecting portion being connected to the auxiliary electrode.