OLED Light Extraction via Refractive Index Gradient
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Solution Overview
Problem
Organic light-emitting devices (OLEDs) face challenges with low light extraction efficiency, which affects their emission efficiency and power consumption.
Innovation Solution
A light-emitting apparatus with a specific structure including a first light-emitting device and a color conversion layer, where the light-emitting device has a layered configuration with organic compounds of varying refractive indices and a color conversion layer that absorbs and emits light, enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional single-layer EL structure is used, then the device structure is simple, but light extraction efficiency is low
Solution Approach 1:
The patent divides the EL layer into multiple sub-layers (first EL layer, second EL layer, third EL layer) with different organic compounds having progressively higher refractive indices. This segmentation allows each layer to contribute differently to light extraction, with the refractive index gradient facilitating better light outcoupling while maintaining a manageable multi-layer structure.
Solution Approach 2:
The patent applies local quality by assigning different refractive index characteristics to different regions of the EL layer. Specifically, the first, second, and third EL layers contain organic compounds with incrementally increasing refractive indices, creating a spatially varying optical property that optimizes light extraction at different depths within the device.
2Productivity
If light extraction efficiency is improved through refractive index optimization, then emission efficiency increases, but device complexity increases
Solution Approach 1:
The patent systematically changes the refractive index parameter across the EL layer stack. By selecting organic compounds with specifically controlled refractive indices that increase from the first to the third EL layer, the patent optimizes light extraction efficiency without requiring excessive structural complexity. This parameter-based approach allows for scalable device design.
3Loss of energy
If multiple organic layers with different refractive indices are used, then light extraction is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent focuses on controlling the refractive index parameter of the organic compounds in each EL layer rather than requiring extremely precise thickness control. By selecting materials with appropriate refractive index values and maintaining reasonable thickness ranges (e.g., 5-50 nm for each layer), the patent achieves effective light extraction while keeping manufacturing precision requirements at practical levels.
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 solution significantly improves light emission efficiency and reduces power consumption in OLEDs by optimizing the refractive index differences in the organic layers and incorporating a color conversion layer to enhance light extraction.
Implementation Method 1
The first color conversion layer includes a first substance that absorbs light and emits light
Implementation Method 2
The first color conversion layer includes a first substance that absorbs light and emits light
Implementation Method 3
The ordinary refractive index of the second organic compound with respect to light with any of the wavelengths greater than or equal to 450 nm and less than or equal to 650 nm is higher than the ordinary refractive index of the first organic compound
Data Source
AI summary
A light-emitting device with high emission efficiency is provided. The light-emitting device includes a first electrode, a second electrode, and an EL layer positioned between the first electrode and the second electrode. The EL layer includes at least a light-emitting layer, a first layer, a second layer, and a third layer. The first layer is positioned between the first electrode and the light-emitting layer. The third layer is positioned between the first layer and the light-emitting layer. The second layer is positioned between the first layer and the third layer. The first layer includes a first organic compound. The second layer includes a second organic compound. The third layer includes a third organic compound. The ordinary refractive index of the second organic compound is higher than the ordinary refractive index of the first organic and the ordinary refractive index of the third organic compound.