OLED Cathode Auxiliary Electrode Mitigates IR Drop
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Solution Overview
Problem
Large resistance in the cathode of OLED display devices leads to internal resistance drops, deteriorating image quality in large-size OLED display devices.
Innovation Solution
Incorporating an auxiliary electrode connected in parallel to the cathode, made of materials identical to the source/drain or gate electrodes, or the anode, to reduce cathode resistance and prevent IR drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the cathode is made thin and transparent/translucent, then the display device achieves better transparency and aesthetics, but the cathode resistance increases causing IR drop
Solution Approach 1:
The patent combines the transparent cathode (first cathode) with an auxiliary electrode (second cathode) having lower resistance to form a composite cathode structure. The auxiliary electrode is positioned adjacent to the transparent cathode and connected to the same anode, creating parallel current paths that reduce overall cathode resistance while preserving the transparency benefits of the thin cathode layer.
Solution Approach 2:
The auxiliary electrode acts as an intermediary element that mediates between the transparency requirement and the resistance problem. It provides an additional conduction path without interfering with the optical properties of the transparent cathode, effectively decoupling the optical and electrical performance requirements.
2Device complexity
If the cathode is made thin to reduce layer thickness, then the device structure is simplified, but internal resistance increases leading to image quality deterioration
Solution Approach 1:
The patent merges the thin transparent cathode with an auxiliary electrode to create a composite structure that maintains the simplicity and thinness of the original cathode while adding the electrical performance benefits of the auxiliary electrode, thereby improving image quality without significantly increasing device complexity.
Solution Approach 2:
The auxiliary electrode is positioned in a different spatial arrangement (adjacent and parallel) rather than stacking it directly on top of the transparent cathode. This lateral positioning in another dimension avoids increasing the vertical layer thickness while still providing the necessary electrical conduction path to reduce resistance and improve image quality.
Data Source
AI summary
The present disclosure provides an OLED display substrate, its manufacturing method and a display device. The OLED display substrate includes a base substrate, and a TFT and an OLED driven by the TFT on the base substrate and. The OLED includes, in a direction away from the base substrate, an anode, an organic layer and a cathode in turn. The OLED display substrate further includes an auxiliary electrode connected in parallel to a part of the cathode.