Light-emitting Device Moisture Removal via Insulating Layer Openings

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Solution Overview

Problem

Conventional light-emitting devices suffer from defects such as dark spots due to moisture diffusion through cracks in the inorganic insulating layer, which are caused by residual and thermal stresses, leading to deterioration of the organic EL elements.

Innovation Solution

The introduction of openings in the inorganic insulating layer allows for the removal of moisture from the organic insulating layer, preventing its diffusion into the light-emitting sections, and the method includes forming these openings before the light-emitting sections are formed to maximize moisture release and protect the organic insulating layer during the manufacturing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an inorganic insulating layer is introduced to protect the organic insulating layer, then protection against moisture is improved, but cracks occur due to residual and thermal stresses

Engineering Contradiction:

Improveprotection against moistureVSAvoidstructural integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The inorganic insulating layer is segmented by forming openings (through-holes) throughout the layer. This segmentation reduces the continuous stress distribution, preventing crack formation while maintaining moisture protection in the regions between openings. The openings divide the rigid structure into manageable segments that can accommodate thermal and residual stresses.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inorganic insulating layer is designed with a porous structure containing openings that extend through the layer. This porous configuration allows the layer to maintain its protective function while accommodating stress through the discontinuous structure, preventing crack propagation that would occur in a solid continuous layer.

Inventive Principle:

Principle #31Porous materials

2Object-affected harmful factors

If the inorganic insulating layer is made continuous to prevent moisture diffusion, then moisture protection is improved, but stress concentration increases leading to cracks

Engineering Contradiction:

Improvemoisture diffusionVSAvoidstress concentration

Core Design Contradiction:

Object-affected harmful factorsVSStress or pressure

Solution Approach 1:

The continuous inorganic insulating layer is segmented by introducing openings, which reduces stress concentration while maintaining moisture barrier functionality in the remaining continuous regions. The segmentation allows stress relief without completely compromising the moisture protection capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The openings act as intermediary elements that mediate between the need for continuous protection and the need for stress relief. They provide pathways for stress accommodation while the surrounding material maintains the moisture barrier function.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of substance

If openings are formed in the inorganic insulating layer to remove moisture, then moisture removal is improved, but the layer structure becomes more complex

Engineering Contradiction:

Improvemoisture removalVSAvoidlayer structure

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

The inorganic insulating layer is designed as a porous structure with openings throughout. This porous configuration naturally facilitates moisture removal through capillary action and evaporation while maintaining a relatively simple overall layer structure that can be integrated into existing device architectures.

Inventive Principle:

Principle #31Porous materials

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

This solution effectively prevents the formation of dark spots, enhancing the reliability of the light-emitting device and the electronic apparatus it is used in by ensuring the removal of moisture and reducing the risk of cracking or peeling of the organic insulating layer.

Implementation Method 1

the openings extend through the respective regions to the organic insulating layer... allows for the removal of moisture from the organic insulating layer

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

preventing its diffusion into the light-emitting sections... moisture contained in the organic insulating layer to be diffused into an organic EL light-emitting element

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS7508004B2Light-emitting device, method for manufacturing light-emitting device, and electronic apparatus

Publication Date: 2009.03.24 SEIKO EPSON CORP

AI summary

A light-emitting device includes an organic insulating layer lying above a face of a substrate, reflective layers arranged on a face of the organic insulating layer, an inorganic insulating layer extending over the reflective layers, pixel electrodes arranged on the inorganic insulating layer, and light-emitting sections arranged on the respective pixel electrodes. The inorganic insulating layer has openings and regions in which no pixel electrodes are arranged when viewed from above. The openings extend through the respective regions to the organic insulating layer. A method for manufacturing such a light-emitting device includes forming openings in regions of the inorganic insulating layer in advance of the formation of the light-emitting sections such that the openings extend through the regions to the organic insulating layer, the regions having no pixel electrodes thereon when viewed from above.