OLED Sealing Layer Porous Inorganic Design
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Solution Overview
Problem
High-density inorganic sealing layers in organic light-emitting displays cause stress and reduce the lifetime of OLEDs under severe environmental conditions, as they effectively prevent moisture and air penetration but lead to pressure or tension stress.
Innovation Solution
Incorporating a porous layer with a density gradient, formed of inorganic materials like SiNx, between the organic light-emitting device and the sealing layer to reduce stress and maintain the display's characteristics over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-density inorganic sealing layer is used to prevent moisture and air penetration, then sealing performance is improved, but stress on the OLED increases and lifetime is reduced
Solution Approach 1:
The sealing structure is divided into multiple inorganic layers with different densities. The lower layer has higher density for effective moisture barrier, while the upper layer has lower density to reduce stress on OLED. This segmentation allows each layer to perform its specific function independently.
Solution Approach 2:
Different regions of the sealing structure have different material densities tailored to local requirements. The lower sealing layer uses high-density material for barrier performance, while the upper sealing layer uses low-density material for stress reduction. This local quality differentiation resolves the contradiction between sealing effectiveness and stress management.
2Object-affected harmful factors
If a high-density inorganic sealing layer is used to block oxygen and moisture, then permeation resistance is improved, but stress-induced black spots form on OLED
Solution Approach 1:
The sealing structure segments the barrier function and stress-management function into different layers. The lower high-density layer provides permeation resistance, while the upper low-density layer prevents stress concentration that causes black spots.
Solution Approach 2:
The multi-layer inorganic sealing structure acts as an intermediary system between the external environment and the OLED. It mediates between the need for strong barrier performance and the need to minimize mechanical stress on the organic light-emitting device.
3Ease of manufacture
If a single high-density inorganic layer is used for sealing, then manufacturing simplicity is maintained, but stress management and long-term stability are compromised
Solution Approach 1:
The sealing layer is segmented into multiple inorganic sub-layers with different densities, forming a stacked structure. This segmentation improves stress management and long-term stability while remaining compatible with existing manufacturing processes like atomic layer deposition.
Solution Approach 2:
The sealing structure uses composite material design with multiple inorganic layers having different densities and properties. This composite approach combines the advantages of high-density materials (barrier performance) and low-density materials (stress reduction) in a single integrated sealing system.
Data Source
AI summary
An organic light-emitting display apparatus is disclosed. In one embodiment, the display apparatus includes i) a substrate and ii) an organic light-emitting device formed on the substrate, the organic light-emitting device including a stack structure including a first electrode, an organic light-emitting layer, and a second electrode. The apparatus may further include a sealing layer formed on the substrate so as to cover the organic light-emitting device, the sealing layer including an inorganic layer and a porous layer interposed between the sealing layer and the organic light-emitting device. One embodiment can reduce a stress due to a sealing inorganic layer so as to maintain characteristics for a long time in a severe environment and not affect an organic light-emitting device.