Multilayer Silicon Nitride Sealing for Organic EL Displays
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Solution Overview
Problem
Conventional organic electroluminescence (EL) display panels face challenges in maintaining sealing properties due to low tolerance for bending and impurities in the sealing layer, which can lead to deterioration from moisture and gases, especially when unevenness or cracks occur.
Innovation Solution
A three-layered sealing structure comprising amorphous silicon nitride films with varying nitrogen-to-silicon ratios, where the second layer has a higher nitrogen content for moisture absorption, enhancing the sealing properties even when cracks appear, and the first and third layers maintain high sealing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon nitride film is formed with high film density to achieve high sealing property, then the sealing property is improved, but the tolerance for bending is reduced and the sealing property deteriorates when unevenness or impurities are present
Solution Approach 1:
The sealing layer is divided into three separate silicon nitride film layers (first, second, and third sealing layers) with different nitrogen content. This segmentation allows each layer to perform different functions: the first and third layers provide high-density sealing, while the second layer with higher nitrogen content provides flexibility and compensates for unevenness, thus resolving the contradiction between high sealing property and bending tolerance.
Solution Approach 2:
Different regions of the sealing layer structure are assigned different nitrogen content to achieve different local properties. The first and third sealing layers have lower nitrogen content for high density and sealing performance, while the second sealing layer has higher nitrogen content for flexibility and unevenness compensation. This local quality differentiation allows the overall structure to simultaneously achieve high sealing property and bending tolerance.
2Reliability
If a three-layered structure with organic film is used to compensate for unevenness, then the sealing property is improved, but the device complexity increases
Solution Approach 1:
Instead of using different materials (such as organic film) to compensate for unevenness, this invention changes the nitrogen content parameter within the same material system (silicon nitride). The second sealing layer has higher nitrogen content than the first and third layers, which provides the necessary flexibility and unevenness compensation while maintaining material consistency and simplifying the manufacturing process.
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 proposed structure effectively prevents sealing property deterioration by absorbing moisture and maintaining high sealing efficacy even with cracks, ensuring improved protection for organic EL elements in organic EL display panels.
Implementation Method 1
the second sealing layer has a moisture absorbing property, and therefore this structure helps to prevent sealing property deterioration even when a crack appears in the sealing layer
Data Source
AI summary
An organic electroluminescence (EL) display panel includes a substrate; a plurality of organic EL elements; and a sealing layer in this order. In the organic EL display panel, the sealing layer has a three-layered structure in the order of a first sealing layer, a second sealing layer, and a third sealing layer. In the organic EL display panel, the first sealing layer, the second sealing layer, and the third sealing layer each include amorphous silicon nitride. In the organic EL display panel, when composition of the first sealing layer, composition of the second sealing layer, and composition of the third sealing layer are each indicated as SiNx, a value of x in the composition of the second sealing layer is greater than both a value of x in the composition of the first sealing layer and a value of x in the composition of the third sealing layer.