Deep-Red TADF Material D-A Structure Singlet-Triplet Gap
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Solution Overview
Problem
Current thermally activated delayed fluorescent materials for deep-red light have low photoluminescence quantum yield and low proportion in the entire thermal activated delayed fluorescent material system, with limited breakthroughs in phosphorescent heavy metal materials.
Innovation Solution
A deep-red light thermally activated delayed fluorescent material is synthesized using a D-A or D-A-D molecular structure with an electron donor and a planar electron acceptor, such as 4,8-dibromo-2,3,6,7-tetracyanonaphthalene, and electron donors like phenoxazine, phenothiazine, or 3,6-dimethoxy-9,9-dimethyl acridine, to reduce the lowest singlet-triplet state energy level difference, facilitating fast reverse intersystem crossing and high photoluminescence quantum yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phosphorescent heavy metal materials are used for deep-red light emission, then the photoluminescence quantum yield can be improved, but the material complexity and environmental sensitivity increase
Solution Approach 1:
The patent changes the energy level parameters of the molecular system by designing specific D-A structures with adjusted HOMO-LUMO gaps and triplet state energies. By controlling the energy level alignment between electron donor and acceptor units, the material achieves deep-red emission with high photoluminescence quantum yield without requiring heavy metal atoms, thus simplifying the material system while maintaining performance.
2Device complexity
If traditional thermally activated delayed fluorescent materials are used, then the device structure can be simplified, but the photoluminescence quantum yield and proportion in the material system remain low
Solution Approach 1:
The patent creates composite molecular structures by combining electron donor units with electron acceptor units to form D-A or D-A-D type molecules. This composite approach allows the material to maintain the structural simplicity of organic fluorescent materials while achieving high photoluminescence quantum yield through optimized energy level alignment and enhanced reverse intersystem crossing efficiency, thus resolving the contradiction between structural simplicity and performance.
3Illumination intensity
If the triplet state energy level is reduced to achieve deep-red emission, then the emission wavelength can be extended, but the reverse intersystem crossing efficiency may decrease
Solution Approach 1:
The patent applies local quality optimization by designing specific functional groups and molecular motifs within the D-A structure that locally enhance the spin-orbit coupling and reverse intersystem crossing pathways. The electron acceptor unit is specifically engineered with cyano groups and aromatic rings that create favorable local electronic environments, allowing efficient reverse intersystem crossing even at reduced triplet state energies required for deep-red emission.
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 synthesized material achieves a high photoluminescence quantum yield and efficient thermal activation delayed fluorescence, enhancing the luminous efficiency and brightness of organic electroluminescent devices with a fast reverse intersystem crossing constant and high production efficiency.
Implementation Method 1
thermally activated delayed fluorescence
Implementation Method 2
fast reverse intersystem crossing constant
Implementation Method 3
fluorescence emission
Implementation Method 4
phosphorescence emission at room temperature
Implementation Method 5
heavy atom effect
Data Source
AI summary
A deep-red light thermally activated delayed fluorescent material and a synthesizing method thereof, and an electroluminescent device are described. The deep-red light thermally activated delayed fluorescent material is a target compound reacted and synthesized by an electron donor and an electron acceptor. The target compound is a D-A molecular structure or a D-A-D molecular structure, wherein the electron acceptor is a planar electron acceptor with an ultra-low triplet state energy level, and a triplet state energy level of the target compound ranges from 1.0 to 2.0 eV. The synthesized deep-red light thermally activated delayed fluorescent material provides high electroluminescent performance, the synthesis efficiency thereof is improved, and the preparation of the highly efficient organic electroluminescent device is realized.