Light-emitting Device Intermediate Protective Layer Crack Prevention
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Solution Overview
Problem
Existing organic electroluminescent devices face challenges in preventing moisture penetration due to cracking of gas barrier layers, which reduces the lifespan and luminescent properties, especially in large-screen displays with thin-film structures.
Innovation Solution
A light-emitting device structure is introduced with an organic buffer layer and an intermediate protective layer having elasticity between the organic buffer layer and the gas barrier layer, preventing direct transmission of thermal distortion and thus minimizing the likelihood of cracking in the gas barrier layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gas barrier layer is formed directly on the organic buffer layer to prevent moisture penetration, then moisture barrier performance is improved, but the gas barrier layer is prone to cracking due to thermal distortion and stress concentration
Solution Approach 1:
An intermediate layer is introduced between the organic buffer layer and the gas barrier layer. This intermediate layer acts as a stress-absorbing mediator that prevents direct transmission of thermal distortion and mechanical stress to the gas barrier layer, thereby eliminating stress concentration points and preventing crack formation while maintaining the moisture barrier function.
Solution Approach 2:
The patent employs a composite multi-layer structure consisting of the organic buffer layer, the intermediate layer with specific elasticity modulus, and the gas barrier layer. This composite structure combines materials with different mechanical properties to achieve both moisture barrier performance and crack resistance, where the intermediate layer's elasticity modulus is specifically designed to be between 2-10 GPa to optimize stress absorption.
2Strength
If the organic buffer layer is made thicker to absorb more stress, then stress absorption capability is improved, but the overall device thickness increases and manufacturing complexity increases
Solution Approach 1:
Instead of increasing the thickness of the organic buffer layer, the patent changes the elastic modulus parameter of the intermediate layer to 2-10 GPa. This parameter optimization allows the intermediate layer to effectively absorb stress with minimal thickness, maintaining device thinness while achieving superior stress absorption capability and simplifying the overall layer structure.
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 configuration effectively prevents moisture penetration and maintains the integrity of the gas barrier layer, enhancing the lifespan and luminescent properties of the light-emitting devices by absorbing stress and reducing defects such as cracks.
Implementation Method 1
an intermediate protective layer, disposed between the organic buffer layer and the gas barrier layer, having an elasticity which is greater than that of the organic buffer layer and which is less than that of the gas barrier layer
Data Source
AI summary
A light-emitting device includes a base; a plurality of first electrodes; a partition having a plurality of openings located at positions corresponding to the first electrodes; organic functional layers each arranged in the corresponding openings; a second electrode covering the partition and the organic functional layers; an organic buffer layer covering the second electrode; a gas barrier layer covering the organic buffer layer; and an intermediate protective layer, disposed between the organic buffer layer and the gas barrier layer, having an elasticity which is greater than that of the organic buffer layer and which is less than that of the gas barrier layer. These layers and electrodes are arranged on or above the base.