OLED Light Extraction via Reflecting Plate and Scattering Layer
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Solution Overview
Problem
In organic light-emitting devices (OLEDs), a significant amount of light is trapped due to total internal reflection between the organic layer and the substrate, leading to low light emission efficiency, as the refractive indices of common materials like indium tin oxide (ITO) and glass result in inefficient light extraction.
Innovation Solution
Incorporating a reflecting plate with high reflectivity outside the transparent electrode layers, a scattering layer between the reflecting plate and the electrode layers, and a planarized layer to enhance light extraction, along with a low refractive region between the substrate and the reflecting plate to minimize surface plasmon effects and absorption losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional OLED structure with transparent electrodes and organic layer is used, then the device structure is simple, but light extraction efficiency is low due to total internal reflection
Solution Approach 1:
The device is segmented into multiple functional layers including a low refractive index layer, scattering layer, and reflecting plate layer, each performing a specific function to collectively improve light extraction while maintaining manufacturing feasibility
Solution Approach 2:
A low refractive index layer is introduced as an intermediary between the organic light-emitting layer and the substrate to reduce refractive index mismatch and minimize total internal reflection, thereby improving light extraction efficiency
2Productivity
If a reflecting plate is added to improve light extraction, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
Multiple functional layers (low refractive index layer, scattering layer, reflecting plate layer) are merged into a single integrated structure that works synergistically to improve light extraction efficiency while avoiding the need for separate complex components
Solution Approach 2:
The reflecting plate layer is designed to perform multiple functions: reflecting extracted light back into the organic layer for re-emission, providing structural support, and maintaining appropriate spacing between components, thereby reducing the need for additional separate components
3Productivity
If the gap between emitting layer and reflecting plate is reduced to enhance light extraction, then light extraction efficiency is improved, but surface plasmon effects and absorption losses increase
Solution Approach 1:
The gap distance between the emitting layer and reflecting plate is optimized to a specific range (100-700nm) to achieve the best balance between light extraction efficiency and minimizing surface plasmon effects and absorption losses, representing a precise parameter optimization
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 improves light extraction efficiency by minimizing evanescent coupling and absorption, resulting in enhanced OLED performance with increased light emission efficiency.
Implementation Method 1
a reflecting plate which is located outside of the first or second transparent electrode layer... having measured reflexibility of 80% or more
Implementation Method 2
a scattering layer between the reflecting plate and the electrode layers
Implementation Method 3
a low refractive region between the substrate and the reflecting plate to minimize surface plasmon effects and absorption losses
Data Source
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AI summary
The present application relates to an organic light emitting device (OLED) and lighting devices. The exemplary OLED according to the present application, for example, may minimize evanescent coupling caused by surface plasmons, and the like, and may have excellent emission efficiency.