Organic Electroluminescent Element with Dibenzofuran Electron Transport
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Solution Overview
Problem
Organic electroluminescence elements using blue phosphorescence face challenges in achieving high light emitting efficiency with low driving voltage and excellent heat and raw stock stability, particularly due to insufficient solution stability and driving voltage of conventional electron transport materials, which limits their practical application in large-area, low-cost, and high-productivity devices.
Innovation Solution
Incorporating an electron transport layer with a compound represented by specific formulas, including dibenzofuran derivatives, and using alkali or alkaline earth metals as electron injection materials to enhance electron transport and reduce driving voltage, while forming organic layers using a wet method to improve film stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electron transport materials are used in organic EL elements using blue phosphorescence, then the element can be constructed with standard materials, but the solution stability and driving voltage are insufficient
Solution Approach 1:
The patent modifies the chemical structure of electron transport materials by introducing specific substituents (such as fluorine atoms, alkyl groups, or aryl groups) at defined positions in the molecular structure. This changes the electronic and steric parameters of the material, resulting in improved solution stability and reduced driving voltage simultaneously.
Solution Approach 2:
The patent employs composite electron transport materials that combine multiple functional groups or moieties within a single molecular structure. These composite structures integrate electron-transporting units with stabilizing groups, achieving both high solution stability and low driving voltage characteristics.
2Use of energy by moving object
If blue phosphorescence emitting material is used, then high light emitting efficiency can be achieved, but high T1 requires precise control of luminescence center and peripheral materials
Solution Approach 1:
The patent introduces host materials as intermediaries between the blue phosphorescence emitting dopant and the electron transport layer. These host materials facilitate energy transfer and stabilize the luminescence center, reducing the complexity of controlling the emission properties while maintaining high light emitting efficiency.
Solution Approach 2:
The patent optimizes the local chemical environment around the phosphorescence emitting material by selecting specific host materials with appropriate HOMO-LUMO energy levels and molecular structures. This local optimization ensures efficient energy transfer and stable emission without requiring complex global control of the entire device structure.
3Object-affected harmful factors
If wet method is used for film formation, then low temperature processing reduces damage to underlying organic layer, but electron transport material stability in solution is insufficient
Solution Approach 1:
The patent designs electron transport materials with molecular structures that are stable in common organic solvents used for wet processing. The materials incorporate rigid aromatic cores and appropriate substituents that prevent degradation in solution, enabling low-cost wet fabrication methods without compromising material stability.
4Manufacturing precision
If multilayer lamination with hole transport layer and electron transport layer is used, then recombination control is improved, but the structure becomes more complex and requires precise material selection
Solution Approach 1:
The patent combines multiple functions into fewer layers by using electron transport materials that also exhibit hole-blocking properties or by integrating electron transport and recombination control functions in a single optimized layer. This reduces the number of layers required while maintaining precise recombination control.
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 light emitting efficiency with low driving voltage and improved heat stability, leading to longer emission lifetime and enhanced productivity in organic electroluminescence elements, suitable for display and lighting devices.
Implementation Method 1
an organic electroluminescence element using phosphorescence luminescence... an exciton is generated by an electron and a hole being injected into the emitting layer to be recombined, resulting emission utilizing light release (fluorescence and phosphorescence) at the time of deactivation of said exciton
Implementation Method 2
Incorporating an electron transport layer with a compound represented by specific formulas, including dibenzofuran derivatives, and using alkali or alkaline earth metals as electron injection materials to enhance electron transport and reduce driving voltage
Implementation Method 3
forming organic layers using a wet method to improve film stability and efficiency
Data Source
Figure 1~3
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Figure 6~7e
AI summary
Disclosed is an organic electroluminescent element which has high luminous efficiency, a low driving voltage, excellent heat resistance, excellent raw stock storabilihy and a long service life.