Organic Electroluminescence Device Electron Transport Layers
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Solution Overview
Problem
Existing organic electroluminescence devices face challenges in achieving both high efficiency and long lifetime due to the limitations in electron transport layers, particularly with the use of compounds having large affinity value gaps and the inclusion of lithium quinolate complexes.
Innovation Solution
The organic electroluminescence device is designed with specific layer configurations, including an anode, an emitting layer with a host material, and electron-transporting layers with carefully selected compounds that have reduced affinity value differences and exclude lithium and lithium quinolate complexes, ensuring optimal electron mobility and layer interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compounds with large affinity value gaps are used in electron-transporting layers, then electron transport efficiency is improved, but material degradation accelerates and lifetime decreases
Solution Approach 1:
The electron-transporting layer is divided into multiple sub-layers with different compounds having progressively smaller affinity value differences. This segmentation allows each sub-layer to contribute to electron transport while collectively reducing material degradation through optimized energy level gradients.
Solution Approach 2:
The invention changes the affinity value difference parameter from large (conventional) to small (0.20 eV or less between adjacent layers), fundamentally altering the electron transport mechanism to reduce energy barriers and minimize degradation while maintaining efficiency.
2Speed
If lithium quinolate complexes are included in electron-transporting layers, then electron mobility is enhanced, but device stability and lifetime are compromised
Solution Approach 1:
The invention extracts and removes lithium quinolate complexes from the electron-transporting layer composition, eliminating the source of degradation while maintaining electron mobility through alternative compound selections with appropriate energy levels.
Solution Approach 2:
The invention replaces unstable lithium quinolate complexes with stable organic compounds that, while individually less mobile, provide sustained long-term performance without degradation, effectively using stable materials to replace unstable high-performance materials.
3Duration of action of stationary object
If affinity value differences between layers are reduced to 0.20 eV or less, then material stability is improved and lifetime extended, but electron transport efficiency may decrease
Solution Approach 1:
Multiple electron-transporting layers with small affinity differences are merged to create a cumulative electron transport pathway. The combined effect of multiple optimized interfaces maintains overall electron mobility while each individual interface contributes to reduced degradation.
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 enhances the device's efficiency while extending its lifetime by optimizing electron transport and reducing material degradation, maintaining high luminous efficiency and operational stability.
Implementation Method 1
a first electron-transporting layer comprising a first compound; a second electron-transporting layer comprising a second compound wherein the electronic mobility of the second electron-transporting layer is less than 1.00×10−4 cm2/Vs
Implementation Method 2
When voltage is applied to an organic electroluminescence device, holes and electrons are injected into an emitting layer from an anode and a cathode, respectively. Then, thus injected holes and electrons are recombined in the emitting layer, and excitons are formed therein.
Data Source
AI summary
An organic electroluminescence device having an anode; an emitting layer containing a host material; a first electron-transporting layer containing a first compound; a second electron-transporting layer containing a second compound; and a cathode in this order, wherein the absolute value of the difference between the affinity value of the host material and the affinity value of the first compound is 0.20 or less, the absolute value of the difference between the affinity value of the first compound and the affinity value of the second compound is 0.20 or less, the first compound and the second compound are different compounds, the electron mobility of the second electron-transporting layer is less than 1.00×10−4 cm2/Vs, the second electron-transporting layer does not contain Li, and the second electron-transporting layer does not contain a quinolate complex of Li.