OLED Dual Encapsulation Layer Moisture Barrier
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Solution Overview
Problem
Organic light emitting diode (OLED) displays face challenges in extending the encapsulation life-span of organic light emitting elements due to the limitations of existing encapsulation methods, particularly in maintaining moisture-proof effectiveness and durability against substrate flexibility.
Innovation Solution
The implementation of a dual encapsulation layer structure, where an organic encapsulation layer covers the organic light emitting elements and an inorganic encapsulation layer contacts the substrate, with a specific geometric configuration to enhance the contact area and moisture-proof effect, ensuring improved encapsulation life-span.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a thin film encapsulation structure is used, then the device thickness is reduced, but the encapsulation life-span and moisture-proof effectiveness deteriorate
Solution Approach 1:
The encapsulation structure is divided into multiple layers: an organic encapsulation layer (first encapsulation layer) and an inorganic encapsulation layer (second encapsulation layer). This segmented approach allows each layer to provide different protective functions, with the inorganic layer providing superior moisture barrier properties while the organic layer provides flexibility and stress relief, thereby extending encapsulation life-span without significantly increasing overall device thickness.
Solution Approach 2:
The patent employs a composite encapsulation structure combining organic and inorganic materials. The organic encapsulation layer (e.g., polymer-based) provides flexibility and adhesion, while the inorganic encapsulation layer (e.g., metal oxide or nitride) provides excellent moisture and oxygen barrier properties. This composite approach achieves both thin profile and enhanced encapsulation durability.
2Reliability
If the inorganic encapsulation layer contacts the substrate, then the moisture-proof effect is improved, but the risk of layer stripping increases under flexible substrate conditions
Solution Approach 1:
The organic encapsulation layer is formed first as a preliminary protective layer before forming the inorganic encapsulation layer. This preliminary organic layer serves as an intermediate buffer that prevents direct contact between the inorganic layer and substrate, pre-establishing a stress-relief mechanism that prevents layer stripping while maintaining moisture-proof effectiveness.
Solution Approach 2:
The organic encapsulation layer acts as an intermediary between the inorganic encapsulation layer and the flexible substrate. This intermediate layer absorbs mechanical stress and prevents direct stress transmission to the inorganic layer, thereby preventing layer stripping while allowing the inorganic layer to maintain its moisture-barrier function through close proximity to the substrate.
3Area of stationary object
If the organic encapsulation layer extends beyond the display area, then the coverage is improved, but the structural complexity increases
Solution Approach 1:
Instead of extending the organic encapsulation layer laterally beyond the display area (increasing planar complexity), the patent utilizes the vertical dimension by stacking the inorganic encapsulation layer above the organic layer. This dimensional transition provides extended coverage and protective functions without proportionally increasing overall structural complexity, as the additional protection is achieved through layering rather than lateral expansion.
Data Source
AI summary
An organic light emitting diode display includes: a substrate; a display area including an organic light emitting element on the substrate; an organic encapsulation layer covering the organic light emitting element and having a second boundary spaced from a first boundary of the display area by a first distance; and an inorganic encapsulation layer having a peripheral area contacting the substrate and covering the organic encapsulation layer.