OLED Pixel Layer Structure for Uniform High-Resolution Displays
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Solution Overview
Problem
The manufacturing of high-resolution, high-definition, and large display devices with organic EL devices is hindered by issues such as non-uniform thickness of island-shaped light-emitting layers due to metal mask blurring and the need for multiple equipment lines, leading to reduced yield and increased initial investment.
Innovation Solution
A method involving the formation of island-shaped light-emitting layers using sacrificial layers and resist masks without a metal mask, allowing for uniform thickness and reducing the need for additional masks, combined with a structure that includes electron-transport layers covering side surfaces of pixel electrodes and light-emitting layers to prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a vacuum evaporation method using a metal mask is used to form island-shaped light-emitting layers, then the light-emitting layers can be formed with different colors, but the outline of the layer may blur during vapor deposition, resulting in non-uniform thickness and reduced manufacturing precision
Solution Approach 1:
The patent divides the manufacturing process into separate steps: first forming the light-emitting layers in island shape using a metal mask, then forming the electron-transport layer to cover side surfaces. This segmentation allows each step to be optimized independently, resolving the contradiction between ease of manufacture and manufacturing precision.
Solution Approach 2:
The patent extends the electron-transport layer to cover not only the top surface but also the side surfaces of the pixel electrode and light-emitting layer, adding a vertical dimension to the coverage. This prevents short circuits while maintaining uniform thickness control in the horizontal plane.
2Productivity
If multiple manufacturing equipment lines are prepared to accommodate metal mask cleaning and maintenance, then continuous production can be maintained, but the initial investment for introducing manufacturing equipment significantly increases
Solution Approach 1:
The patent applies a protective electron-transport layer in advance that covers the side surfaces of the light-emitting layer. This preliminary action prevents contamination and damage during subsequent handling, reducing the frequency and complexity of maintenance operations and allowing single-line production.
3Reliability
If the electron-transport layer is formed to cover side surfaces of pixel electrodes and light-emitting layers, then short circuits are prevented and reliability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The electron-transport layer serves multiple functions: it transports electrons, covers and protects the side surfaces of the light-emitting layer, prevents short circuits, and provides a base for subsequent layers. This multi-functionality improves reliability without significantly increasing device complexity.
Data Source
AI summary
A high-resolution or high-definition display device is provided. The display device includes a first light-emitting device and a second light-emitting device. The first light-emitting device includes a first pixel electrode, a first hole-injection layer, a first hole-transport layer, a first light-emitting layer, a first electron-transport layer, a second electron-transport layer, and a common electrode that are stacked in this order. The second light-emitting device includes a second pixel electrode, a second hole-injection layer, a second hole-transport layer, a second light-emitting layer, a third electron-transport layer, a second electron-transport layer, and a common electrode that are stacked in this order. The first light-emitting device and the second light-emitting device have a function of emitting light of different colors from each other. The second electron-transport layer covers at least a side surface of the first pixel electrode, a side surface of the second pixel electrode, a side surface of the first light-emitting layer, and a side surface of the second light-emitting layer.