Light-Emitting Element with TADF-TTA Layers for Efficiency and Longevity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing organic electroluminescence elements face challenges in achieving low driving voltage, high luminous efficiency, and long service life, necessitating advancements in materials for stable performance.
Innovation Solution
A light emitting element comprising a first emission layer with a (1-1)-th compound and a second emission layer with a (2-1)-th compound, where the (2-1)-th compound has a lowest excited triplet energy level of 1.5 eV to 2.1 eV, configured to emit fluorescence through thermally activated delayed fluorescence (TADF) and triplet-triplet annihilation (TTA), with additional layers for hole and electron transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional organic electroluminescence materials are used, then the element can operate, but the luminous efficiency and service life are insufficient
Solution Approach 1:
The patent optimizes the triplet energy level parameter of the second emission layer material to be within 1.5-2.1 eV, which is lower than the triplet energy level of the first emission layer. This parameter change enables efficient triplet exciton transfer from the first to the second emission layer, improving both luminous efficiency and service life by utilizing triplet state energy through triplet-triplet annihilation fluorescence emission.
2Productivity
If triplet state energy is utilized through phosphorescence emission, then luminous efficiency improves, but the element structure becomes more complex
Solution Approach 1:
The second emission layer material serves multiple functions: it acts as a host material for the emission layer, provides the appropriate triplet energy level for efficient exciton transfer, and enables triplet-triplet annihilation fluorescence emission. This multi-functionality allows the patent to improve luminous efficiency by utilizing triplet state energy without requiring separate phosphorescence emission layers or additional complex structures.
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 enhances luminous efficiency and service life, resulting in improved display quality by optimizing the luminescence characteristics and element longevity.
Implementation Method 1
pertaining to fluorescence, which uses triplet-triplet annihilation (TTA) in which singlet excitons are generated by the collision of triplet excitons
Implementation Method 2
Research and development are presently directed thermally activated delayed fluorescence (TADF) materials that use delayed fluorescence phenomenon
Data Source
AI summary
Embodiments provide a light emitting element and a display device that includes the light emitting element. The light emitting element includes a first electrode, a first emission layer disposed on the first electrode and including a (1-1)-th compound, a second emission layer disposed on the first emission layer and including a (2-1)-th compound, and a second electrode disposed on the second emission layer, wherein the (2-1)-th compound has a lowest excited triplet energy level (T1) in a range of about 1.5 eV to about 2.1 eV. The (1-1)-th compound is represented by Formula 1, the (2-1)-th compound is represented by Formula 2, and Formula 1 and Formula 2 are each described in the specification.