OLED Cathode-Auxiliary Electrode Bank Structure to Prevent Burnt
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Solution Overview
Problem
In top emission type organic light emitting display devices, the high resistivity of the cathode electrode leads to voltage drops, resulting in non-uniform luminance and image quality, especially as the size of the display panel increases, and there is a risk of short-circuit burns between the cathode and auxiliary electrodes due to their connection.
Innovation Solution
The implementation of a multi-layer bank structure with an undercut in the lowest layer adjacent to the auxiliary electrode allows for direct connection between the cathode and auxiliary electrodes, while an electron transport layer is deposited over the entire surface, facilitating contact and preventing short-circuit burns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the cathode electrode is formed thin to be semi-transmissive with low work function, then the transparency and work function are improved, but the resistance increases causing voltage drop
Solution Approach 1:
The cathode electrode is divided into two parts: a thin semi-transmissive cathode layer for light emission and an auxiliary electrode layer for electrical connection. This segmentation allows each layer to optimize its function - the cathode layer maintains transparency while the auxiliary electrode provides low-resistance electrical path
Solution Approach 2:
The auxiliary electrode acts as an intermediary between the thin cathode layer and the power supply. It provides a low-resistance electrical connection path that compensates for the high resistance of the thin cathode layer, enabling stable voltage application without significant voltage drop
2Reliability
If the cathode and auxiliary electrodes are directly connected, then the electrical connection is improved, but short-circuit burns may occur
Solution Approach 1:
The electron transport layer serves as an intermediary barrier between the cathode electrode and the auxiliary electrode. It prevents direct contact that would cause short-circuit burns while maintaining proper electrical connection through controlled electron transport
Solution Approach 2:
The electron transport layer is selectively positioned only in regions where the cathode and auxiliary electrodes need to be electrically connected, while maintaining other functional areas unchanged. This localized application prevents short-circuits at critical connection points
3Area of stationary object
If the display panel size is increased, then the area is improved, but the voltage drop is intensified
Solution Approach 1:
The electrode system is segmented into multiple components (cathode layer, auxiliary electrode, electron transport layer) that work together to distribute electrical connection points across the large panel area, reducing the distance electrons must travel through high-resistance material and minimizing overall voltage drop
Data Source
AI summary
The present disclosure relates to an organic light emitting display device and a method for manufacturing the same. In the organic light emitting display device according to the present disclosure, a bank which exposes an auxiliary electrode connected to a cathode electrode of an organic light emitting device is composed of multiple layers, and particularly, since the lowest layer of the bank, which is adjacent to the auxiliary electrode, includes an undercut, the cathode electrode and the auxiliary electrode are directly connected so that it is possible to prevent burnt due to a short-circuit between the cathode electrode and Ag included in the auxiliary electrode.