Light-emitting Device Planarization Layer Inward Edge
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Solution Overview
Problem
Organic EL display devices face issues with moisture degradation, leading to the formation of non-light-emitting dark spots and reduced lifespan due to the large frame width around the light-emitting region, caused by the distance between the outer edge of the light-emitting layer and the sealing structure.
Innovation Solution
A light-emitting device configuration with a planarization layer positioned inward of the light-emitting layer's outer edge, reducing the frame width and enhancing moisture protection by overlapping the planarization layer with the dummy electrodes and contact portion, thereby minimizing the distance to the light-emitting layer and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing structure is positioned to cover the light-emitting layer completely, then moisture protection is improved, but the frame width around the light-emitting region becomes large
Solution Approach 1:
The patent changes the spatial arrangement by positioning the planarization layer's outer edge inward relative to the light-emitting layer's outer edge, rather than extending outward to provide sealing. This dimensional repositioning allows the sealing function to be achieved through vertical layering and material properties rather than horizontal extension, thereby reducing frame width while maintaining moisture protection.
Solution Approach 2:
The patent employs a composite sealing structure combining the planarization layer with the underlying organic buffer layer and gas barrier layer. This composite approach allows the sealing function to be distributed across multiple layers with different properties, enabling effective moisture protection without requiring the planarization layer to extend beyond the light-emitting layer boundaries.
2Reliability
If the planarization layer extends beyond the light-emitting layer, then sealing is improved, but the distance from the light-emitting layer to the device edge increases
Solution Approach 1:
The patent repositions the planarization layer inward rather than extending it outward, changing the sealing strategy from horizontal coverage to vertical layering. This allows the effective sealing distance to be minimized while maintaining protection through the stacked layer structure and inherent material barrier properties.
3Length of stationary object
If the frame width is reduced by positioning the planarization layer inward, then device compactness is improved, but sealing effectiveness may be compromised
Solution Approach 1:
The patent compensates for the reduced horizontal coverage by creating a composite sealing system where the planarization layer works in conjunction with the organic buffer layer and gas barrier layer. Each layer contributes different protective properties, and their combination maintains sealing effectiveness even with minimal frame width.
Solution Approach 2:
The patent applies different functional properties to different regions: the planarization layer provides local planarity and protection where needed, while the underlying buffer and barrier layers provide the primary sealing function. This localized functional distribution allows compact dimensions while maintaining sealing effectiveness through specialized material properties in critical regions.
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 configuration reduces the frame width around the light-emitting region, enhances moisture protection, and increases the reliability of the light-emitting device by allowing early detection of defects and improving manufacturing yield.
Implementation Method 1
a light-emitting layer 251, and a sealing layer 40 including a planarization layer 28, wherein the first electrode 21 is arranged between the substrate 20 and the second electrode 26, the light-emitting layer 251 is arranged between the first electrode 21 and the second electrode 26, and emits light in accordance with the current flowing through the light-emitting layer 251
Data Source
AI summary
A light-emitting device includes a substrate having a circuit thereon, a first electrode electrically coupled to the circuit, a second electrode, a light-emitting layer, and a sealing layer including a planarization layer, wherein the first electrode is arranged between the substrate and the second electrode, the light-emitting layer is arranged between the first electrode and the second electrode and emits light in accordance with a current flowing through the light-emitting layer, the planarization layer is arranged on an opposite side of the second electrode from a side on which the light-emitting layer is arranged, and an outer edge of the planarization layer is located inward of an outer edge of the light-emitting layer in plan view.