Bipolar Organic Compound for OLED Emissive Layer Efficiency
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Solution Overview
Problem
Conventional OLEDs face limitations in luminous efficiency and lifetime, particularly for blue emission, due to the short luminous lifetime of metal complex phosphorescent materials and deteriorated properties of existing luminous materials.
Innovation Solution
An organic compound with a high excited triplet energy level and bipolar properties is introduced, featuring a fused aromatic ring with a benzimidazole moiety for electron affinity and a fused hetero aromatic ring or aromatic amino group for hole affinity, enhancing thermal stability and charge mobility, which is incorporated into the emissive layer of OLEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metal complex phosphorescent materials are used in OLEDs, then luminous efficiency is improved, but luminous lifetime becomes too short for commercial application
Solution Approach 1:
The patent changes the chemical composition parameters by replacing metal complex phosphorescent materials with organic compounds containing specific structures (triazine, pyrimidine, pyridine rings with electron-donating groups). This parameter change maintains high luminous efficiency through effective charge transport while dramatically extending luminous lifetime by eliminating metal complex degradation pathways, making the material suitable for commercial OLEDs.
2Reliability
If conventional fluorescent materials are used in OLEDs, then material stability is maintained, but luminous efficiency is low due to only singlet excitons involvement
Solution Approach 1:
The patent creates composite material characteristics by designing organic compounds that combine multiple functional moieties: electron-donating groups (carbazole, triphenylamine) for hole transport, electron-withdrawing groups (triazine, pyrimidine, pyridine rings) for electron transport, and specific ring structures for stability. This composite structure enables bipolar charge transport capability while maintaining excellent thermal and chemical stability, achieving high luminous efficiency without sacrificing material reliability.
3Illumination intensity
If blue emission luminous materials are used in OLEDs, then color purity is achieved, but luminous properties and luminous lifetime are deteriorated
Solution Approach 1:
The patent applies local quality by introducing specific functional groups at particular positions within the molecular structure. Electron-donating groups are positioned to enhance hole transport and stabilize the blue emission state, while electron-withdrawing groups are strategically placed to improve electron affinity and extend lifetime. This localized functional group placement optimizes both color purity and luminous lifetime for blue emission OLEDs.
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 organic compound improves luminous efficiency, extends the luminous lifetime, and reduces driving voltage, enabling more efficient and stable OLED performance, particularly for blue emission.
Implementation Method 1
In the OLED, holes injected from an anode and electrons injected from a cathode are recombined in an EML to form excitons as an unstable excites state, and then the light emits as the exciton is shifted to a stable ground state.
Data Source
AI summary
The present disclosure relates to an organic compound having the following structure, and an organic light emitting diode (OLED) and an organic light emitting device including the organic compound. The organic compound is a bipolar compound having a p-type moiety and an n-type moiety and has high energy level and proper energy bandgap for an emissive layer of the OLED. As the organic compound is applied into the emissive layer, the OLED can maximize its luminous properties as holes and electrons are recombined uniformly over the whole area in an EML.