OLED Encapsulation Using Ambipolar Copolymer to Reduce Cavity Formation

Solution Overview

Problem

Conventional OLED display panel encapsulation structures face issues with inkjet printing ink flow and uniformity on inorganic layers, leading to cavity formation in organic layers, which allows water, oxygen, and impurities to penetrate, resulting in shorter product life and oxidation of OLED devices.

Innovation Solution

An OLED display panel encapsulation structure comprising a first inorganic layer, a first organic ambipolar layer made of organic copolymer with hydrophilic and hydrophobic groups, and a second inorganic layer, where the organic layer is formed using spray technology with a composition of alkenoic acid ester, alkenoic acid, and photopolymerization initiator, reducing cavity formation and enhancing water and oxygen isolation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If inkjet printing is used to form organic layers on inorganic layers, then the manufacturing process can be implemented, but the ink is difficult to flow and spread uniformly, leading to cavity formation

Engineering Contradiction:

Improvemanufacturing process implementationVSAvoidink uniformity and cavity formation

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the surface energy parameter of the inorganic layer by introducing a hydrophilic layer (such as SiOx or ALD-treated surface) between the inorganic layer and organic layer. This parameter change modifies the wettability characteristics, enabling the hydrophobic organic ink to spread uniformly without forming droplets or cavities, thus resolving the manufacturing precision issue while maintaining ease of manufacture

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a hydrophilic intermediary layer (SiOx layer or ALD-treated inorganic layer surface) between the inorganic layer and organic layer. This intermediary layer acts as a mediator that facilitates uniform ink spreading by providing appropriate surface energy characteristics, preventing direct poor interaction between hydrophobic ink and hydrophilic inorganic layer

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If conventional inorganic and organic layers are stacked, then encapsulation structure can be formed, but water, oxygen and impurities penetrate through cavities, resulting in shorter product life

Engineering Contradiction:

Improveencapsulation structure formationVSAvoidproduct life and oxidation resistance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent changes the surface energy parameter of the inorganic layer by introducing a hydrophilic layer (such as SiOx or ALD-treated surface) between the inorganic layer and organic layer. This parameter change modifies the wettability characteristics, enabling the hydrophobic organic ink to spread uniformly without forming droplets or cavities, thus resolving the manufacturing precision issue while maintaining ease of manufacture

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a hydrophilic intermediary layer (SiOx layer or ALD-treated inorganic layer surface) between the inorganic layer and organic layer. This intermediary layer acts as a mediator that facilitates uniform ink spreading by providing appropriate surface energy characteristics, preventing direct poor interaction between hydrophobic ink and hydrophilic inorganic layer

Inventive Principle:

Principle #24Intermediary (Mediator)

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 reduces cavity formation in the organic layer, improving the OLED device's ability to isolate water and oxygen, thereby extending the product life and reducing oxidation risks.

Implementation Method 1

molecules of the organic copolymer have hydrophilic groups and hydrophobic groups

Methodology Applied

Scientific EffectHydrophilic groups and hydrophobic groups interaction: Amphiphiles

Implementation Method 2

the first organic layer is formed on the first inorganic layer by utilizing a spray technology

Methodology Applied

Scientific EffectSpray deposition: Spray

Implementation Method 3

ink used in the spray technology is made of a composition comprising alkenoic acid ester organic substance, alkenoic acid organic substance and photopolymerization initiator

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS10707444B2OLED display panel encapsulation structure and OLED display device

Publication Date: 2020.07.07 WUHAN CHINA STAR OPTOELECTRONICS SEMICONDUCTOR DISPLAY TECHNOLOGY CO LTD

AI summary

An organic light emitting diode (OLED) display panel encapsulation structure includes a first inorganic layer, a first organic layer and a second inorganic layer stacked with one another. The organic layer is an ambipolar layer and the ambipolar layer is made of organic copolymer. Molecules of the organic copolymer have hydrophilic groups and hydrophobic groups. The present invention further provides an OLED display device including a substrate, a thin-film transistor driver layer, an OLED luminescent layer, and an OLED display panel encapsulation structure.