Organic EL Device Intermediate Layer Light Extraction
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Solution Overview
Problem
Conventional organic electroluminescent light emitting devices face limitations in light extraction efficiency due to the refractive index mismatch between organic materials, anodes, and substrates, leading to high total reflection and low external quantum efficiency.
Innovation Solution
Incorporating a transparent intermediate layer with fine particles and a flattened layer on a transparent substrate, where the fine particles are adhered to the substrate and covered by a layer with a different refractive index, reducing total reflection and enhancing light extraction through scattering and refraction effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional organic electroluminescent light emitting device structure is used, then the device is simple to manufacture, but the light extraction efficiency is low due to refractive index mismatch
Solution Approach 1:
The patent introduces an intermediate layer between the substrate and the organic light emitting layer. This intermediate layer has a refractive index that is intermediate between the substrate and the organic materials, serving as a refractive index bridge to reduce total internal reflection and improve light extraction efficiency without complicating the manufacturing process
Solution Approach 2:
The intermediate layer is constructed as a composite material consisting of transparent resin and fine particles with different refractive indices. This composite structure allows optimization of the effective refractive index to match the requirements for reducing optical reflection, while maintaining ease of manufacturing through conventional coating processes
2Device complexity
If the refractive index mismatch between organic materials, anode, and substrate is not addressed, then the device structure remains simple, but total reflection is high and external quantum efficiency is low
Solution Approach 1:
The intermediate layer acts as an optical intermediary that mediates the refractive index transition between the substrate and organic materials. This reduces total internal reflection at the interfaces, thereby improving external quantum efficiency without significantly increasing device structural complexity
Solution Approach 2:
The patent modifies the refractive index parameter of the intermediate layer by adjusting the composition and concentration of fine particles within the transparent resin matrix. This parameter optimization enables effective reduction of optical reflection while maintaining a relatively simple device 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 significantly increases light extraction efficiency, achieving near 100% internal quantum efficiency and improving external quantum efficiency, while maintaining a simple and cost-effective manufacturing process.
Implementation Method 1
enhancing light extraction through scattering and refraction effects
Implementation Method 2
enhancing light extraction through scattering and refraction effects
Data Source
AI summary
According to one embodiment, an organic electroluminescent light emitting device includes a transparent substrate, an intermediate layer, a first electrode, an organic light emitting layer, and a second electrode. The intermediate layer includes a plurality of fine particles and a flattened layer. The fine particles are adhered to a major surface of the transparent substrate. The flattened layer covers the fine particles and has a refractive index different from a refractive index of the fine particles. The flattened layer is transparent. The first electrode is provided on the intermediate layer. The first electrode is transparent. The organic light emitting layer is provided on the first electrode. The second electrode is provided on the organic light emitting layer.