Phosphorescent Host Material for Organic EL Device Efficiency
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Solution Overview
Problem
Current organic electroluminescence (EL) devices have limitations in terms of half-life time, current efficiency, and driving voltage, which affect their performance and power consumption.
Innovation Solution
An organic compound represented by formula (1) is used as a phosphorescent host material in the emitting layer, collocated with a dopant material like Ir(ppy)3, to enhance luminance, current efficiency, and half-life time in organic EL devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fluorescent materials are used in organic EL devices, then the device structure is simple, but the internal quantum efficiency is limited to 25% due to triplet exciton energy loss as heat
Solution Approach 1:
The patent changes the key parameter of the emitting material from fluorescent to phosphorescent, which fundamentally alters the spin-orbit coupling properties and enables triplet state emission. This parameter change allows the device to utilize both singlet and triplet excitons for light emission, achieving internal quantum efficiency up to 100% while maintaining a relatively simple device structure.
Solution Approach 2:
The patent converts the previously harmful triplet excitons (which caused energy loss as heat in fluorescent materials) into beneficial light-emitting states. By using phosphorescent materials with heavy atoms that enable spin-orbit coupling, the triplet excitons that were wasted energy in fluorescent devices become the primary source of light emission, achieving efficient energy utilization.
2Reliability
If prior art organic materials are used, then the device can operate, but the half-life time, current efficiency, and driving voltage are insufficient
Solution Approach 1:
The patent employs composite phosphorescent materials combining heavy metal atoms (Ir, Pt, Os) with organic ligands to create phosphorescent dopants. These composite materials exhibit enhanced photostability, longer half-life time, and improved current efficiency compared to prior art organic materials, while maintaining device operability. The composite structure allows for optimized electronic properties and reduced degradation.
3Use of energy by moving object
If phosphorescent materials are used to improve internal quantum efficiency to 100%, then energy utilization improves, but the device complexity increases due to spin-orbit interaction requirements
Solution Approach 1:
The patent uses phosphorescent dopants (Ir(ppy)3, PtOEP, Os(ppy)3) as intermediaries within the emitting layer to mediate the conversion of electrical energy to light. These intermediary materials facilitate spin-orbit coupling and enable efficient triplet state emission without requiring fundamental changes to the overall device structure, thus achieving high internal quantum efficiency with manageable complexity.
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 use of the organic compound as a phosphorescent host material increases luminance to 900-1341 cd/m2, current efficiency to 21-36 cd/A, and extends the half-life time to 472-998 hours under the same voltage, outperforming prior art materials.
Implementation Method 1
phosphorescent organic EL devices make use of spin-orbit interactions to facilitate intersystem crossing between singlet and triplet states, thus obtaining emission from both singlet and triplet states and the internal quantum efficiency of electroluminescence devices from 25% to 100%
Implementation Method 2
make use of spin-orbit interactions to facilitate intersystem crossing between singlet and triplet states
Implementation Method 3
The basic mechanism of organic EL involves the injection, transport, and recombination of carriers as well as exciton formation for emitting light
Data Source
AI summary
The present invention discloses an organic compound represented by the following formula (1) and an organic electroluminescence device using the organic compound as the phosphorescent host material, the fluorescent host material, or the fluorescent dopant material. The organic compound may increase a current efficiency or half-life of the organic electroluminescence device.