Flexible OLED Encapsulation with Grooved Inorganic Layers

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Solution Overview

Problem

Flexible OLED panels face stress concentration issues during bending or surface roughness testing, leading to cracking or peeling of the inorganic layer, which affects their reliability and surface roughness performance.

Innovation Solution

The flexible display device incorporates a structure with a flexible substrate, a thin film transistor, a luminescent layer, and an encapsulation layer comprising a first and second inorganic layer, with grooves in the first inorganic layer filled with an organic material to disperse stress, and an optional crack suppression structure with additional grooves to reduce the risk of cracking or peeling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the inorganic layer is used to block water and oxygen in the flexible encapsulation structure, then the reliability of the flexible OLED panel is improved, but the inorganic layer is prone to crack or peel during dynamic bending or reliability testing due to stress concentration

Engineering Contradiction:

Improvereliability of flexible OLED panelVSAvoidcrack resistance of inorganic layer

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent divides the encapsulation layer into multiple segments: inorganic layers (first and second) for blocking water and oxygen, and organic layers (third and fourth) for stress relief. This segmentation allows each layer to perform its specialized function, preventing the inorganic layer from cracking under stress while maintaining reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs a composite encapsulation structure combining inorganic and organic materials. The inorganic layers provide barrier properties against water and oxygen, while the organic layers provide flexibility and stress distribution. This composite approach resolves the contradiction by integrating the advantages of both material types.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If the organic layer is used to coat particles and relieve stress, then the flexibility of the panel is improved, but the stress of the inorganic layer in the patterned area becomes significantly concentrated

Engineering Contradiction:

Improveflexibility of panelVSAvoidstress concentration in inorganic layer

Core Design Contradiction:

Adaptability or versatilityVSStress or pressure

Solution Approach 1:

The patent applies different material properties to different locations: the organic layer is specifically positioned between the inorganic layers in stress-prone areas to provide localized stress relief, while the inorganic layers maintain their barrier function in areas requiring water and oxygen blocking. This local differentiation resolves the stress concentration issue.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The organic layer is pre-positioned between the inorganic layers to act as a cushioning layer that absorbs and distributes stress before it can concentrate in the inorganic layer. This preventive measure ensures the inorganic layer remains intact during bending and reliability testing.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the encapsulation layer is made with laminated films of inorganic/organic/inorganic layers, then the protection against water and oxygen is improved, but the manufacturing complexity increases due to multiple layers and processes

Engineering Contradiction:

Improveprotection against water and oxygenVSAvoidmanufacturing complexity of encapsulation layer

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent designs the organic layer to serve multiple functions simultaneously: it acts as a stress-relief layer, a barrier layer (in combination with inorganic layers), and a flattening layer for particles. This multi-functionality reduces the need for additional separate layers, simplifying the overall manufacturing process while maintaining protection.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the barrier function of organic and inorganic layers into an integrated encapsulation system where the organic layer and inorganic layers work together as a unified structure. This merging approach maintains effective protection while reducing the number of separate manufacturing steps compared to using multiple thin inorganic layers alone.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11424270B2Flexible display device and manufacturing method thereof

Publication Date: 2022.08.23 WUHAN CHINA STAR OPTOELECTRONICS SEMICONDUCTOR DISPLAY TECHNOLOGY CO LTD

AI summary

A flexible display device and a method of manufacturing thereof are provided. The flexible display device includes a flexible substrate, a thin film transistor disposed on the flexible substrate, a luminescent layer disposed on the thin film transistor, a first retaining wall and a second retaining wall disposed on the thin film transistor, and an encapsulation layer. The encapsulation layer includes a first inorganic layer, an organic layer, and a second inorganic layer. The first inorganic layer covers the first retaining wall, the second retaining wall, and one part of the thin film transistor. A plurality of first grooves are disposed in the first inorganic layer. The organic layer fills the plurality of first grooves and covers the luminescent layer and the other part of the thin film transistor. The second inorganic layer covers the first inorganic layer and the organic layer.