Space-Through Charge Transfer Compound for OLED Efficiency
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Solution Overview
Problem
Current organic light emitting diodes (OLEDs) face limitations in emitting efficiency, particularly for blue phosphorescent compounds, which have not met requirements in terms of efficiency and reliability, resulting in suboptimal performance.
Innovation Solution
A space-through charge transfer compound with a biphenyl core, electron acceptor, and electron donor moieties is used, reducing the overlap between highest occupied and lowest unoccupied molecular orbitals, enabling efficient charge transfer and utilizing both singlet and triplet excitons for emission, thereby enhancing emitting efficiency and providing deep blue emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phosphorescent compounds are used to improve emitting efficiency, then both singlet and triplet excitons can be engaged in emission, but blue phosphorescent compounds do not meet requirements in emitting efficiency and reliability
Solution Approach 1:
The patent changes the chemical structure parameters of the emitting material by introducing a space-through charge transfer compound with specific donor and acceptor moieties. This structural parameter change enables the material to utilize both singlet and triplet excitons for emission while achieving high stability and long lifespan for blue emission, resolving the contradiction between emitting efficiency and reliability.
Solution Approach 2:
The patent employs a composite molecular structure consisting of electron donor and electron acceptor moieties connected through a biphenyl core. This composite structure creates a charge transfer complex that enables efficient exciton utilization while maintaining high stability, thereby achieving both high emitting efficiency and reliability simultaneously.
2Device complexity
If fluorescent compounds are used, then the device structure is simpler, but the internal quantum efficiency is limited to a maximum value of 0.25 because only singlet excitons are engaged in emission
Solution Approach 1:
The patent changes the quantum mechanical parameters of the emitting material by creating a charge transfer compound with specific HOMO-LUMO orbital arrangements. This enables the material to access both singlet and triplet exciton pathways for emission, achieving internal quantum efficiency exceeding 0.25 while maintaining a relatively simple OLED device structure.
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 space-through charge transfer compound improves OLED emitting efficiency, achieves long lifespan, and provides deep blue emission with high quantum efficiency, surpassing the limitations of traditional fluorescent compounds.
Implementation Method 1
A space-through charge transfer compound with a biphenyl core, electron acceptor, and electron donor moieties is used, reducing the overlap between highest occupied and lowest unoccupied molecular orbitals, enabling efficient charge transfer
Implementation Method 2
when the electron from a cathode, which serves as an electron-injecting electrode, and the hole from an anode, which serves as a hole-injecting electrode, are injected into an emitting material layer, the electron and the hole are combined and become extinct such that the light is emitted from the OLED
Data Source
AI summary
The present disclosure provides a space-through charge transfer compound of following formula and an organic light emitting diode and an organic light emitting display device including the space-through charge transfer compound.