OLED Cathode Electrode Integration for Aperture Ratio
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Solution Overview
Problem
The existing organic light emitting display devices have a reduced aperture ratio due to the space occupied by the initialization voltage line and via hole, which limits the pixel opening size.
Innovation Solution
The organic light emitting display device design eliminates the need for a separate initialization voltage line by using the cathode electrode to apply the initialization voltage, allowing for a wider pixel opening by removing the initialization voltage line and via hole, thereby improving the aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate initialization voltage line and via hole are formed in each pixel, then the initialization voltage can be supplied to the initialization transistor, but the aperture ratio is reduced due to the space occupied by these structures
Solution Approach 1:
The patent merges the initialization voltage line function with the cathode electrode by making the cathode electrode extend to connect to the source electrode of the initialization transistor. This integration eliminates the need for a separate initialization voltage line and via hole, thereby removing the space occupation that reduced the aperture ratio while maintaining the initialization voltage supply function.
Solution Approach 2:
The cathode electrode is designed to serve multiple functions: it acts as the common cathode for the OLED and simultaneously serves as the initialization voltage line by extending to connect to the source electrode of the initialization transistor. This multi-functionality eliminates the need for separate initialization voltage supply structures, improving the aperture ratio.
2Area of stationary object
If the initialization voltage line and via hole are removed, then the aperture ratio is improved, but a separate structure for supplying initialization voltage must be eliminated
Solution Approach 1:
The patent combines the cathode electrode and initialization voltage line into a single integrated structure. The cathode electrode extends beyond the OLED to connect with the source electrode of the initialization transistor, thereby eliminating the separate initialization voltage line and via hole structures while maintaining the necessary electrical connection for initialization voltage supply.
Data Source
AI summary
An organic light emitting display device includes an active layer of a transistor disposed on a substrate, a gate electrode disposed on the active layer and on a first insulation layer, a second insulation layer which is disposed on the gate electrode and exposes a source area and a drain area of the active layer, a drain electrode which is disposed on the second insulation layer and is connected to an exposed area of the drain area, a third insulation layer on the drain electrode, and a cathode electrode on the third insulation layer, where the cathode electrode penetrates the first insulation layer, the second insulation layer and the third insulation layer, and the cathode electrode is connected to an exposed area of the source area.