Transparent Electrode Microparticles for OLED Light Extraction
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Solution Overview
Problem
Existing organic electroluminescent elements face challenges in achieving high light extraction efficiency due to the need for separate light-scattering layers, which increase manufacturing costs and risk damage from gas generation, and limited efficiency gains from reducing refractive index differences with small conductive nanoparticles.
Innovation Solution
An organic electroluminescent element is designed with a substrate, a first transparent electrode containing particles with a primary size of 0.5 μm or more, a low refractive-index layer with a refractive index of 1.3 or less, and a reflector layer, where the first transparent electrode's content rate and film thickness satisfy specific relationships to enhance light extraction efficiency without requiring a separate light extraction layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a separate light-scattering layer is added to improve light extraction efficiency, then light extraction efficiency is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the light-scattering function and electrode function into a single transparent electrode layer containing microparticles. This merging eliminates the need for a separate light-scattering layer while maintaining both light extraction efficiency and electrical conductivity, directly resolving the technical contradiction between improving light extraction and reducing device complexity
Solution Approach 2:
The transparent electrode is designed to perform multiple functions simultaneously: it serves as both the electrical conductor and the light-scattering layer. By incorporating microparticles with specific refractive indices into the transparent electrode, the structure achieves universal functionality, eliminating redundant layers and simplifying the overall device structure
2Loss of energy
If a separate light-scattering layer is added to improve light extraction efficiency, then light extraction efficiency is improved, but manufacturing cost increases
Solution Approach 1:
By merging the light-scattering layer and electrode into a single integrated transparent electrode structure, the patent reduces the number of manufacturing steps. The transparent electrode is formed in one process that simultaneously provides both electrical conductivity and light scattering, eliminating the need for separate deposition or assembly steps for a dedicated light-scattering layer, thereby reducing manufacturing cost
3Loss of energy
If small conductive nanoparticles are used to reduce refractive index difference, then light extraction efficiency is slightly improved, but the efficiency gain is limited
Solution Approach 1:
The patent changes the particle size parameter from nanoscale to microscale (0.5 μm or more), which fundamentally alters the light scattering mechanism. This parameter change enables much stronger light scattering effects and significantly higher light extraction efficiency compared to using small nanoparticles, directly addressing the limitation of insufficient efficiency improvement
Solution Approach 2:
The patent introduces microparticles with specific local optical properties (refractive index of 1.3 or less) into the transparent electrode to create localized regions of high light scattering. This local quality enhancement at specific positions within the electrode structure produces disproportionate improvements in overall light extraction efficiency
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 allows for improved light extraction efficiency and cost-effectiveness by integrating light-scattering functionality into the transparent electrode, eliminating the need for a separate light extraction layer and reducing the risk of gas-related damage.
Implementation Method 1
a low refractive-index layer with a refractive index of 1.3 or less... to reduce the absorptivity of a reflector layer
Implementation Method 2
the aforementioned first transparent electrode contains at least one type of transparent particle with a primary particle size of 0.5 μm or more
Implementation Method 3
an organic layer including at least one organic light-emitting layer... a self-emitting type of light-emitting device
Data Source
AI summary
[It is an object] to provide an organic electroluminescent element having a transparent electrode, with which there is no need to produce a separate light extraction layer, [which can be produced by] a simple film formation process, and which is advantageous in terms of cost. [This is] an organic electroluminescent element in which a substrate, a first transparent electrode that is adjacent to this substrate, an organic layer including at least one organic light-emitting layer, a second transparent electrode, a low refractive-index layer with a refractive index of 1.3 or less, and a reflector layer are formed in this order, with this organic electroluminescent element being such that the aforementioned first transparent electrode contains at least one type of transparent particle with a primary particle size of 0.5 μm or more.