OLED Common Voltage Applying Layer Side Surface Contact
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Solution Overview
Problem
The manufacturing process of OLED display devices is complicated and costly due to the difficulty in connecting the common electrode to the common voltage applying layer, especially when using an open mask, which leads to issues with the deposition of organic layers and increased resistance in the common electrode.
Innovation Solution
A display device design where the common voltage applying layer is formed between the insulating substrate and the common electrode, with a contact hole exposing side surfaces of the common voltage applying layer to facilitate electrical connection, and an organic insulating layer is used to separate the common voltage applying layer from the organic layer, allowing for a stable and efficient application of common voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common voltage applying layer is provided to compensate for the high resistance of the common electrode, then the voltage application is improved, but the manufacturing process becomes more complex due to the need for additional connection structures
Solution Approach 1:
The patent transitions from planar connection (top surface contact) to three-dimensional connection by utilizing the side surface of the common voltage applying layer. The contact hole penetrates through the organic insulating layer to expose the side surface of the common voltage applying layer, enabling vertical electrical connection. This dimensional change simplifies the manufacturing process by allowing direct side-surface contact without requiring complex overlapping structures.
2Ease of manufacture
If an open mask is used to form organic layers, then the manufacturing process is simplified, but the organic layer deposits in the contact hole preventing connection between the common electrode and common voltage applying layer
Solution Approach 1:
The patent performs preliminary actions by: (1) forming the contact hole through the organic insulating layer to expose the side surface of the common voltage applying layer before organic layer deposition; (2) forming the common electrode that contacts the exposed side surface; and (3) then depositing the organic layer using an open mask. This sequence ensures the electrical connection is established before the organic layer is deposited, preventing the connection blockage issue while maintaining the simplicity of open mask fabrication.
3Shape
If the common electrode is formed of transparent conductive metal like ITO or IZO, then the top emission type display is achieved, but the resistance becomes too large to appropriately apply common voltage
Solution Approach 1:
The patent introduces a common voltage applying layer as an intermediary between the common electrode and the external voltage source. This layer has lower resistance than the transparent common electrode, allowing it to efficiently conduct common voltage across the display area. The common voltage applying layer is positioned adjacent to the common electrode and connected through a contact hole, serving as a low-resistance pathway that compensates for the high resistance of the transparent common electrode material.
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 and reduces costs by enabling easier connection of the common electrode to the common voltage applying layer, even when using an open mask, while maintaining efficient voltage application and light emission through the common electrode.
Implementation Method 1
The common electrode is electrically connected to a side surface contact portion of the common voltage applying layer which is exposed through the contact hole
Implementation Method 2
If a voltage is applied to the pixel electrode and the common electrode, a hole and an electron combine to generate an exciton. The exciton transitions to the ground state and emits light in the emitting material layer
Data Source
AI summary
A display device, includes: an insulating substrate; a common electrode which is formed on the insulating substrate; a common voltage applying layer which is formed between the insulating substrate and the common electrode, and comprises an upper surface which faces the common electrode and a side surface of the opposite sides of the upper surface; and an organic insulating layer which is formed between the insulating substrate and the common electrode, and is formed with a contact hole which exposes at least a part of the side surface of the common voltage applying layer, the common electrode electrically connected to a side surface contact portion of the common voltage applying layer which is exposed through the contact hole.