LED Display Encapsulation Structure for Moisture Barrier Reliability
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Solution Overview
Problem
Display devices using light emitting diodes (LEDs) face issues with moisture permeation, which leads to defects and reduced display quality due to the organic layer's vulnerability.
Innovation Solution
A display device structure is implemented with multiple inorganic passivation layers and an adhesive layer to minimize moisture permeation, including a substrate with active and non-active areas, transistors, planarization layers, light emitting diodes, and a protection layer covered by an inorganic third passivation layer, enhancing the stability and reliability of the LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an organic layer is used above the light emitting diode, then the device structure can be simplified, but moisture permeation increases leading to LED defects
Solution Approach 1:
The patent employs a composite encapsulation structure combining organic and inorganic layers. Specifically, it uses an organic encapsulation layer (first encapsulation layer) combined with inorganic encapsulation layers (second encapsulation layer made of alternating high-density and low-density inorganic layers) to create a composite barrier that leverages the advantages of both material types while mitigating their individual weaknesses regarding moisture permeation
Solution Approach 2:
The inorganic encapsulation layer is segmented into multiple sub-layers with different density characteristics. The second encapsulation layer comprises alternating high-density inorganic layers and low-density inorganic layers, creating a multi-segmented barrier structure that provides enhanced moisture protection compared to a single-layer approach
2Reliability
If multiple inorganic passivation layers are added to reduce moisture permeation, then LED reliability improves, but device complexity increases
Solution Approach 1:
The patent employs a composite encapsulation structure combining organic and inorganic layers. Specifically, it uses an organic encapsulation layer (first encapsulation layer) combined with inorganic encapsulation layers (second encapsulation layer made of alternating high-density and low-density inorganic layers) to create a composite barrier that leverages the advantages of both material types while mitigating their individual weaknesses regarding moisture permeation
Solution Approach 2:
The encapsulation structure serves multiple functions simultaneously: the organic first encapsulation layer provides basic protection and serves as an adhesive layer, while the inorganic second encapsulation layer provides enhanced moisture barrier functionality. This multi-functional design achieves comprehensive protection without requiring entirely separate systems for each function
Data Source
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AI summary
According to an aspect of the present disclosure, a display device (100) includes a substrate (110) including an active area (AA) in which the plurality of sub pixels (SP) is disposed and a non-active area (NA) which encloses the active area (AA); a plurality of transistors (DT) disposed in each of the plurality of sub pixels (SP); a first passivation layer (115a) which covers the plurality of transistors (DT) and is formed of an inorganic material; a first planarization layer (116a) which covers the first passivation layer (115a); a second passivation layer (115b) which covers the first planarization layer (116a) and is formed of an inorganic material; an adhesive layer (AD) disposed on the second passivation layer (115b); a plurality of light emitting diodes (130) disposed on the adhesive layer (AD); a first protection layer (117) disposed on the adhesive layer (AD) and the plurality of light emitting diodes (130); and a third passivation layer (115c) which covers the first protection layer (117) and is formed of an inorganic material.