Light-Emitting Module With Gas Barrier Substrate
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Solution Overview
Problem
Organic electroluminescence elements face challenges in light extraction efficiency and reliability due to the diffusion of impurities from the high refractive index light-scattering layer, which affects the emission of light from the light-emitting organic compound layer.
Innovation Solution
A light-emitting module structure is developed using an element substrate with gas barrier properties, where a light-emitting element is optically connected to one surface and a diffuse reflection layer with high diffuse reflectance is provided on the other surface, with the refractive index difference between the substrate and the light-emitting organic compound layer minimized to enhance light extraction and prevent impurity diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light-scattering layer with high refractive index is provided to improve light extraction efficiency, then light extraction efficiency is improved, but impurities diffuse from the light-scattering layer to the light-emitting layer causing reliability to decrease
Solution Approach 1:
The patent introduces an element substrate as an intermediary layer between the light-emitting element and the diffuse reflection layer. This substrate has gas barrier properties that prevent impurity diffusion while maintaining optical transmission. The refractive index of the element substrate is specifically controlled to be within 0.2 of the light-emitting organic compound layer to enable effective light extraction without requiring a high refractive index light-scattering layer that would cause impurity diffusion.
Solution Approach 2:
The patent extracts the light scattering function from the traditional light-scattering layer and relocates it to a separate diffuse reflection layer. This separation allows the light-emitting element to be sealed without the high refractive index material that causes impurity diffusion, while still achieving effective light extraction through the element substrate and diffuse reflection layer combination.
2Illumination intensity
If the refractive index difference between the element substrate and the light-emitting organic compound layer is minimized, then light extraction efficiency is improved, but the ability to prevent waveguide formation must be maintained
Solution Approach 1:
The patent addresses waveguide formation by introducing a spatial separation in the optical path. The element substrate with controlled refractive index and the separate diffuse reflection layer create a multi-dimensional optical structure that prevents total internal reflection conditions while maintaining efficient light extraction. The diffuse reflection layer is positioned at a specific distance from the light-emitting element, creating a geometric configuration that disrupts waveguide formation.
3Reliability
If a sealing structure is provided to improve reliability by preventing impurity diffusion, then reliability is improved, but light extraction efficiency may be compromised
Solution Approach 1:
The element substrate serves multiple functions simultaneously: it provides gas barrier properties for sealing and reliability, transmits light for optical functionality, and controls refractive index for light extraction efficiency. This multi-functional design eliminates the need for separate sealing structures that would compromise light extraction, as the element substrate itself provides both protection and optical performance.
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 improves light extraction efficiency and reliability by preventing waveguide formation and reducing impurity diffusion, resulting in a more effective and durable light-emitting module.
Implementation Method 1
a diffuse reflection layer is provided for the other surface side of the element substrate... the diffuse reflectance of the diffuse reflection layer is greater than or equal to 75% and less than 100%
Implementation Method 2
The element substrate transmits light emitted from the light-emitting element; the refractive index of the element substrate is different from that of the layer containing a light-emitting organic compound by 0.2 or less
Implementation Method 3
an element substrate with gas barrier properties is used... preventing waveguide formation and reducing impurity diffusion
Data Source
AI summary
A light-emitting module with improved light extraction efficiency and reliability is provided. In the light-emitting module, an element substrate with gas barrier properties is used; a light-emitting element is optically connected to one surface side of the element substrate; and a diffuse reflection layer is in contact with the other surface side of the element substrate. The diffuse reflection layer has a diffuse reflectance of greater than or equal to 75% and less than 100%. The light-emitting element includes a layer containing a light-emitting organic compound between a pair of light-transmitting electrodes. The element substrate transmits light emitted from the light-emitting element; the refractive index of the element substrate is different from that of layer containing a light-emitting organic compound by 0.2 or less.