Boron-Aromatic Emission Material for Blue OLED Efficiency and Lifetime
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Solution Overview
Problem
Current organic electroluminescent (EL) devices face challenges in achieving high emission efficiency and long-term stability, particularly for blue organic EL devices, and existing delayed fluorescence mechanisms have limitations in efficiency.
Innovation Solution
The development of an emission material represented by a specific general formula, incorporating a boron atom and specific aromatic rings, which is used in the light emitting layer of an organic EL device, along with a host material like triazine or anthracene compounds, to enhance emission efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent organic EL device is used to enhance internal quantum efficiency up to 100%, then emission efficiency is improved, but device lifetime is insufficient particularly for blue devices
Solution Approach 1:
The patent changes the emission mechanism parameter from phosphorescence to delayed fluorescence (TTF mechanism), and optimizes the energy level parameters by selecting host and dopant materials with specific triplet energy levels (Et) where 2.7 eV < Et(host) < 3.2 eV and 2.3 eV < Et(dopant) < 2.8 eV, achieving both high efficiency and long lifetime in blue emission
Solution Approach 2:
The patent uses composite material system consisting of host material (e.g., Alq3, BCP, Bpy-OXD) and dopant material (e.g., Bpy-OXD derivatives) with specific molecular structures containing boron atoms and aromatic rings, creating a synergistic system that achieves high efficiency and stability
2Use of energy by moving object
If delayed fluorescence with TTF mechanism is used to enhance internal quantum efficiency up to 40%, then emission efficiency is improved, but efficiency is still low compared to phosphorescent organic EL device
Solution Approach 1:
The patent optimizes the energy level parameters by selecting host and dopant materials with specific triplet energy levels, and controls the molecular structure parameters of the dopant (containing boron atom with specific aromatic rings) to achieve efficient triplet-triplet fusion while maintaining high emission efficiency comparable to phosphorescent devices
3Adaptability or versatility
If organic EL device is applied to display device such as flat panel display and light source, then practical application is enabled, but emission efficiency needs to be improved and driving stability needs to be ensured
Solution Approach 1:
The patent optimizes the energy level parameters and molecular structure parameters of the emission material to achieve high efficiency and long lifetime, enabling practical application in display devices with sufficient driving stability
Solution Approach 2:
The patent uses composite material system with specific host and dopant materials that provide both high emission efficiency and long operational lifetime, ensuring driving stability for practical display applications
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 results in an organic EL device with improved emission efficiency and prolonged driving stability, effectively addressing the limitations of current technologies.
Implementation Method 1
The TTF mechanism utilizes a phenomenon in which a singlet exciton is generated by the collision of two triplet excitons
Implementation Method 2
When a voltage is applied to an organic EL device, holes and electrons are injected from the anode and the cathode, respectively, into the light emitting layer. Then, the injected holes and electrons are recombined in the light emitting layer to thereby generate excitons
Implementation Method 3
The TADF mechanism utilizes a phenomenon in which reverse intersystem crossing occurs from the triplet exciton to the singlet exciton in a material having a small energy difference between the singlet level and the triplet level
Implementation Method 4
In the fluorescent organic EL device that uses emission caused by singlet excitons
Implementation Method 5
in the phosphorescent organic EL device that uses emission caused by triplet excitons
Data Source
Figure 1
AI summary
Provided are an emission material and an organic EL device including the emission material and having high emission efficiency and a long lifetime. An organic EL device comprising light emitting layers between an anode and a cathode opposite to each other; wherein at least one of the light emitting layers contains, as a light emitting dopant, a compound in which a backbone having a specific 5-ring-fused ring structure, and a boron atom are combined, and the compound is represented by the following general formula (1).