Nitrogen-Containing Emission Layer for OLED Service Life
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Solution Overview
Problem
There is a demand for organic electroluminescence devices with low driving voltage, high luminous efficiency, and long service life, and existing materials struggle to stably achieve these characteristics.
Innovation Solution
An organic electroluminescence device incorporating a nitrogen-containing compound with an aromatic monocycle, triazine, or triazatruxene group as a thermally activated delayed fluorescence emitting material, which is used in the emission layer to enhance efficiency and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials are used in the emission layer, then the device structure is simple, but the luminous efficiency and service life cannot be stably improved
Solution Approach 1:
The patent modifies the chemical structure parameters of the emission layer materials by introducing specific nitrogen-containing groups (triazine, triazatruxene) and adjusting molecular weight and substitution patterns. This changes the photophysical properties to achieve longer service life and higher efficiency without fundamentally changing the device architecture.
Solution Approach 2:
The patent employs composite material strategies by combining nitrogen-containing aromatic monocycles with carbazole groups, triazine groups, and triazatruxene groups in specific molecular architectures. These composite molecular structures synergistically improve both service life and luminous efficiency while maintaining reasonable structural complexity.
2Productivity
If materials with high luminous efficiency are used, then the external quantum yield increases, but the delayed fluorescence lifetime may increase reducing efficiency
Solution Approach 1:
The patent optimizes the balance between luminous efficiency and delayed fluorescence lifetime by precisely adjusting molecular weight (400-2000 Da), nitrogen content (1-10 atoms per molecule), and substitution patterns on the aromatic rings. These parameter changes enable short delayed fluorescence lifetime (maintaining high productivity) while achieving high external quantum yield (30-60%).
Solution Approach 2:
The patent introduces localized nitrogen-containing functional groups (triazine, triazatruxene) at specific positions on the aromatic monocycle framework. This local modification optimizes the electronic structure to facilitate rapid radiative decay (short lifetime) while maintaining high quantum efficiency, resolving the contradiction between speed and efficiency.
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 device achieves improved luminous efficiency and extended service life by utilizing the nitrogen-containing compound, which facilitates efficient delayed fluorescence emission, thereby increasing external quantum yield and reducing the delayed fluorescence lifetime.
Implementation Method 1
an organic electroluminescence device including a thermally activated delayed fluorescence emitting material
Implementation Method 2
holes and electrons respectively injected from a first electrode and a second electrode recombine in an emission layer, and thus a luminescent material including an organic compound in the emission layer emits light
Data Source
AI summary
An organic electroluminescence device of an embodiment of the present disclosure includes a first electrode, a hole transport region disposed on the first electrode, an emission layer disposed on the hole transport region, an electron transport region disposed on the emission layer, and a second electrode disposed on the electron transport region, wherein the emission layer may include a nitrogen-containing compound represented by Formula 1, thereby exhibiting a long service life. In Formula 1, at least one of A1 to A5 is represented by Formula 2, and at least another one of A1 to A5 is represented by Formula 3: