Polycyclic Boron-Nitrogen Compound for OLED Emission Layer
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Solution Overview
Problem
Current organic electroluminescence display devices face challenges in achieving low driving voltage, high luminous efficiency, and long service life, particularly in the development of materials for light emitting elements that can stably exhibit these characteristics.
Innovation Solution
A light emitting element is designed with a specific polycyclic compound in the emission layer, including compounds represented by Formulas 1, HT-1, ET-1, and M-b, which are used in combination to enhance luminous efficiency and service life, with the emission layer emitting delayed fluorescence and having a central wavelength in the range of 430 nm to 490 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional materials are used in the emission layer, then the device structure is simple, but the luminous efficiency and service life are insufficient
Solution Approach 1:
The emission layer employs a composite material system consisting of a host compound (Formula HT-1 or ET-1) and a polycyclic luminescent dopant (Formula 1) with specific structural features (n1+n2=2-8, R1-R5 substituents). This composite approach enables high luminous efficiency and long service life through synergistic interactions between host and dopant materials, resolving the contradiction between performance improvement and material complexity.
2Use of energy by moving object
If phosphorescence emission materials are used, then energy utilization is improved, but the service life and stability are insufficient
Solution Approach 1:
The patent utilizes thermally activated delayed fluorescence (TADF) mechanism by designing compounds with specific energy level parameters (E(S1)-E(T1)≤2.1 eV) and structural features (boron-nitrogen heterocyclic core with spirobifluorene substituents). This parameter optimization enables efficient triplet exciton utilization through triplet-triplet annihilation while maintaining material stability and achieving service life exceeding 1000 hours at 1000 cd/m² brightness.
3Ease of manufacture
If simple emission layer materials are used, then manufacturing is easy, but the driving voltage and efficiency cannot be optimized
Solution Approach 1:
The emission layer employs compounds with locally optimized structural features: the host (Formula HT-1 or ET-1) provides appropriate HOMO/LUMO energy levels for charge injection, while the dopant (Formula 1) with boron-nitrogen heterocyclic core and specific substituents (R1-R5, n1+n2=2-8) provides high quantum efficiency. This local quality optimization enables low driving voltage and high efficiency while maintaining relatively simple fabrication processes.
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 luminous efficiency and extended service life for the light emitting element, improving the performance of organic electroluminescence display devices by using the specified polycyclic compounds in the emission layer.
Implementation Method 1
delayed fluorescence emission which uses the generation of singlet excitons by the collision of triplet excitons (triplet-triplet annihilation, TTA)
Implementation Method 2
development is currently directed to a material for thermally activated delayed fluorescence (TADF) using a delayed fluorescence mechanism
Implementation Method 3
a so-called self-luminescent light emitting element in which holes and electrons respectively injected from a first electrode and a second electrode recombine in an emission layer, so that a luminescent material of the emission layer emits light
Data Source
AI summary
Embodiments provide a light emitting element that includes a first electrode, a second electrode disposed on the first electrode, and an emission layer disposed between the first electrode and the second electrode. The emission layer includes a polycyclic compound represented by Formula 1, which includes a boron-containing core moiety, and a spiro-bifluorene substituent, thereby exhibiting high efficiency and long service life characteristics: