OLED Light Outcoupling via Porous Mixed Metal Oxide Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current OLEDs suffer from low internal light outcoupling efficiency, with only 20% of generated light able to exit the multilayer stack due to absorption or reflection at interfaces, leading to reduced external light outcoupling and increased power consumption.
Innovation Solution
Incorporating a thin, porous, and transparent mixed metal oxide layer, specifically indium zinc oxide, between the ITO and HTL in the OLED structure, which is produced through a cost-effective process involving precursor composition application, drying, and rapid heating to enhance internal light outcoupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a standard OLED multilayer structure is used, then the device structure is simple and manufacturing is easy, but the internal light outcoupling efficiency is low with only 20% of generated light able to exit
Solution Approach 1:
A thin porous layer of mixed metal oxides (containing indium, zinc, and aluminum) is introduced as an intermediary layer between the ITO anode and the hole transport layer. This intermediary layer has a refractive index of 1.6-1.8 that bridges the optical impedance mismatch between ITO and organic layers, enabling improved light outcoupling efficiency while maintaining ease of manufacture through solution-based processing
Solution Approach 2:
The mixed metal oxide layer is designed with controlled porosity (30-70% pore volume) to reduce optical reflection and enhance light extraction. The porous structure creates gradient refractive index transitions and reduces optical impedance mismatch, allowing more generated light to exit the device while the layer remains thin (10-100 nm) and compatible with standard OLED manufacturing
2Use of energy by moving object
If the light outcoupling efficiency is increased to reduce power consumption, then energy efficiency improves, but the device structure becomes more complex
Solution Approach 1:
The mixed metal oxide layer parameters are optimized to achieve the right balance: thickness of 10-100 nm (preferably 20-50 nm), porosity of 30-70%, and refractive index of 1.6-1.8. These parameter changes enable improved power efficiency through enhanced light outcoupling while keeping the structural addition minimal and compatible with existing OLED architectures
Solution Approach 2:
The use of mixed metal oxides (combining indium, zinc, and aluminum) creates a composite material with tailored optical and electrical properties. This composite approach allows simultaneous optimization of refractive index for light outcoupling, conductivity for charge transport, and porosity for reduced reflection, achieving improved power efficiency without significant structural complexity
3Loss of energy
If a thin porous layer of mixed metal oxides is added to improve internal light outcoupling, then light outcoupling efficiency increases by up to 20%, but the manufacturing process becomes more complex
Solution Approach 1:
The mechanical/physical vapor deposition methods are replaced with solution-based processing where mixed metal oxide precursors are applied by spin-coating, dip-coating, or spray-coating, then converted to functional oxide layers through thermal treatment. This substitution dramatically simplifies manufacturing while achieving the desired light outcoupling improvement
Solution Approach 2:
The thermal treatment parameters (temperature, time, atmosphere) are optimized to convert precursor layers into functional mixed metal oxide layers with the desired porosity (30-70%) and refractive index (1.6-1.8). This parameter optimization enables consistent production of high-performance outcoupling layers through simple, scalable processes
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 approach significantly improves internal light outcoupling by up to 20%, reducing power consumption and increasing the overall efficiency of OLEDs while maintaining device performance.
Implementation Method 1
The porous layer has a refractive index of from 1.6 to 1.8... significantly improves internal light outcoupling by up to 20%
Implementation Method 2
only 20% of the light generated is able to leave the multilayer stack due to absorption or reflection at the interfaces within the device
Implementation Method 3
converting the dried layer into the corresponding thin porous and transparent mixed metal oxide layer by rapid heating
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to OLEDs (Organic Light Emitting Devices) with increased light outcoupling, to a process for the production of OLEDs comprising additional light outcoupling layers, and to the use thereof.