OLED Color Pixel Structure With Low-Threshold Layer Against Leakage
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Solution Overview
Problem
In organic electroluminescent displays, leakage current between adjacent pixels of different luminescent colors leads to color shift and gradation issues due to varying threshold voltages, limiting material selection and increasing light emission from adjacent pixels.
Innovation Solution
A display device with separated luminescent layers for each color and a low-threshold layer with a lower threshold voltage than the luminescent layers, where a continuous layer allows current to flow to the low-threshold layer, reducing leakage current between adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous layer is used over all pixels to ensure productivity, then manufacturing efficiency is improved, but leakage current between adjacent luminescent layers increases causing color shift
Solution Approach 1:
The patent segments the continuous layer into pixel-specific regions and introduces a low-threshold layer between adjacent pixels. This segmentation allows the continuous layer to maintain its productivity benefit while the low-threshold layer acts as a barrier to prevent leakage current between adjacent luminescent layers of different colors.
Solution Approach 2:
The low-threshold layer serves as an intermediary layer between adjacent luminescent layers with different threshold voltages. It mediates the current flow by providing a lower threshold path that prevents direct leakage between high-threshold luminescent layers, thereby eliminating color shift while maintaining the continuous layer structure for manufacturing efficiency.
2Object-generated harmful factors
If equivalent threshold voltage is used for all luminescent layers to prevent leakage current, then leakage current is reduced, but material selection freedom is lost
Solution Approach 1:
The patent applies local quality by having different threshold voltage characteristics in different regions. The luminescent layers can maintain their color-specific threshold voltages (red, green, blue) while the low-threshold layer provides a localized lower threshold region between adjacent pixels. This allows material selection freedom for each luminescent color while preventing leakage current through the low-threshold intermediary layer.
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
The solution effectively reduces leakage current between different-color light-emitting regions, minimizing color shift and enhancing display performance by directing current flow through the low-threshold layer, thus improving color accuracy and gradation.
Implementation Method 1
A current is drawn from the continuous layer to the low-threshold layer, thereby reducing the leakage current between the pair of different-color light-emitting regions
Data Source
AI summary
A display device includes: light-emitting regions different in luminescent colors and including luminescent layers separated for each of the luminescent colors; a low-threshold layer lower in threshold voltage than any one of the luminescent layers included in a pair of different-color light-emitting regions included in the light-emitting regions, different in the luminescent colors, and adjacent to each other; a continuous layer under the luminescent layers and the low-threshold layer, including first areas and a second area continuously, the first areas being in contact with the respective light-emitting regions, the second area being in contact with the low-threshold layer; pixel electrodes under the continuous layer, overlapping with the respective light-emitting regions; and a counter electrode over the luminescent layers and the low-threshold layer, being opposed to the pixel electrodes. The low-threshold layer is between the pair of different-color light-emitting regions.