Organic Electroluminescent Device Blue Light Guest Material
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Solution Overview
Problem
Current organic electroluminescent devices face limitations in internal quantum efficiency due to the utilization of fluorescent materials, which can only harness the singlet excited state, resulting in a maximum efficiency of 25%, and there is a need for improved blue light guest materials with enhanced performance.
Innovation Solution
An organic compound with a norborneol-fluorene, cyclohexane-fluorene, or cyclopentane-fluorene structure is developed, fused with a solid ring centered on the boron element, to enhance carrier transport efficiency, stability, and luminescent performance by improving electron density and hole transport efficiency within the organic electroluminescent device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fluorescent materials are used in the light-emitting layer, then the device structure is simple, but the internal quantum efficiency is limited to maximum 25% because only singlet excited state can be utilized
Solution Approach 1:
The patent changes the emission mechanism parameter from pure fluorescent (singlet only) to phosphorescent (triplet utilized) by introducing phosphorescent materials with heavy atoms that enable triplet-triplet fusion, converting the 75% triplet excited states into usable singlet emissions and achieving internal quantum efficiency exceeding 25%
Solution Approach 2:
The patent employs composite materials by combining fluorescent and phosphorescent materials in the light-emitting layer, where the phosphorescent component facilitates triplet-triplet fusion to generate singlet excited states that can emit light, thereby utilizing both singlet and triplet excitons to overcome the 25% efficiency limit
2Loss of energy
If triplet-triplet-fusion (TTF) phenomenon is utilized to improve internal quantum efficiency, then the efficiency can reach 62.5%, but the device requires phosphorescent materials with complex structure
Solution Approach 1:
The patent applies local quality by introducing heavy atoms (Ir, Pt, Au) only in the phosphorescent dopant molecules within the light-emitting layer, rather than throughout the entire device structure. This localized approach enables TTF phenomenon and high efficiency while keeping the overall device structure relatively simple and manageable
3Loss of energy
If blue light guest materials are developed to improve device performance, then the luminous efficiency can be enhanced, but the service life of the device decreases
Solution Approach 1:
The patent optimizes the molecular structure parameters of blue light guest materials by incorporating specific heterocyclic groups and electron-donating/withdrawing substituents that balance high luminous efficiency with improved thermal stability and reduced degradation, thereby extending device service life while maintaining 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 proposed organic compound significantly improves the carrier transport efficiency, stability, and luminescent performance of organic electroluminescent devices, increasing luminous efficiency and extending the service life by at least 13.8% and 12% respectively compared to previous devices.
Implementation Method 1
TTF is the phenomenon of generating one molecule in a singlet excited state from two molecules in a triplet excited state. By using the phenomenon, the singlet excited state can be produced from the generated triplet excited state of 75%, and the maximum internal quantum efficiency becomes 62.5%.
Implementation Method 2
In the organic electroluminescent device, holes and electrons which are injected from the anode and the cathode are recombined in the light-emitting layer, and the energy generated at this time is derived in the form of light.
Data Source
AI summary
The present disclosure relates to an organic compound, an organic electroluminescent device using the same, and an electronic apparatus. The organic compound has a structure obtained by fusing a formula (1) with one or two Ar groups. The Ar group is selected from the group consisting of groups shown in formulae (2-1) to (2-5). The organic compound can be used in an organic electroluminescent device and can improve the performance of the organic electroluminescent device.