Organic Electroluminescent Element with Thin Anode Layer
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Solution Overview
Problem
Conventional organic electroluminescent elements require high driving voltage and exhibit low luminescence luminance and efficiency, with existing solutions either compromising on durability or color purity.
Innovation Solution
An organic electroluminescent element comprising an anode, cathode, and multiple organic compound layers with a luminescent layer containing a host material and two or more phosphorescent materials, where the layer adjacent to the anode has a thickness of 50 nm or less and the layer adjacent to the cathode has a compound with an ionization potential of 6.0 eV or less, enhancing durability and color purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional organic luminescent elements are used, then they can emit light through electron-hole recombination, but they require high driving voltage and exhibit low luminescence luminance and efficiency
Solution Approach 1:
The patent changes the chemical composition parameters of the organic compound layers, specifically using a host material with high electron mobility and LUMO level, and optimizing the dopant concentration and type. This allows the element to achieve low driving voltage while maintaining high luminescence efficiency through improved charge injection and transport properties
Solution Approach 2:
The patent employs composite organic compound layers combining host materials with specific electron transport properties and phosphorescent dopants. The composite structure enables simultaneous achievement of low driving voltage and high luminescence efficiency by leveraging the synergistic effects of the host-guest system
2Reliability
If BCP (Bathocuproine) is used as the organic compound layer, then it can provide hole blocking function, but since BCP has a high ionization potential (6.1 eV), satisfactory durability cannot be obtained
Solution Approach 1:
The patent changes the ionization potential parameter of the hole blocking layer material by selecting an organic compound with ionization potential of 6.0 eV or less, specifically designed to have lower ionization potential than BCP. This enables the material to effectively block holes while improving durability by reducing the energy barrier that causes material degradation
Solution Approach 2:
The patent replaces the high ionization potential material (BCP) with a more suitable organic compound that has lower ionization potential, effectively substituting a material that causes durability problems with one that is optimized for both hole blocking function and long-term stability
3Power
If the organic compound layer thickness is reduced to 50 nm or less, then driving voltage can be lowered, but the layer becomes more sensitive to defects and manufacturing variations
Solution Approach 1:
The patent optimizes the thickness parameter of the organic compound layer to 50 nm or less, which reduces the voltage drop across the layer and enables low driving voltage operation. The specific thickness range is carefully selected to balance voltage reduction with manufacturing feasibility
4Productivity
If phosphorescent materials are used in the luminescent layer, then luminescence efficiency can be improved, but color purity may be compromised
Solution Approach 1:
The patent applies local quality by selecting specific phosphorescent dopants with well-defined emission characteristics and optimizing their concentration in the host material. This localized optimization of the dopant distribution and type enables high luminescence efficiency while maintaining color purity through controlled energy transfer and minimized spectral broadening
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 achieves high external quantum efficiency, excellent durability, and low driving voltage while maintaining color purity, as demonstrated by the use of specific dopants and layer configurations in the organic electroluminescent element.
Implementation Method 1
Luminescence is a phenomenon in which energy is emitted in the form of light, when the electrons and the holes are recombined in the luminescent layer, and the electrons return to the valence band from the conductive band
Data Source
AI summary
The present invention provides an organic electroluminescent element including an anode, a cathode, and a plurality of organic compound layers including at least one organic luminescent layer between the anode and the cathode, in which the organic luminescent layer contains a host material and two or more phosphorescent materials; the organic luminescent layer is adjacent to the organic compound layers at both an anode side and a cathode side thereof; the organic compound layer disposed adjacent to the organic luminescent layer at the anode side thereby has a thickness of 50 nm or less in thickness; and the organic compound layer disposed adjacent to organic luminescent layer at the cathode side thereby contains a compound having an ionization potential of 6.0 eV or less. The present invention also provides a display device using the organic electroluminescent element.