Benzochrysene Derivative for Organic EL Lifetime and Efficiency
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Solution Overview
Problem
Existing organic electroluminescence (EL) devices face challenges in achieving long lifetime and high efficiency while operating at low voltage, with existing emission materials not fully addressing these requirements.
Innovation Solution
A benzochrysene derivative with a specific structure is used as a material for organic EL devices, enhancing the device's lifetime and efficiency and allowing for low-voltage operation by forming a fused aromatic ring derivative that serves as an emitting material in the device's structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional emission materials are used in organic EL devices, then the device can achieve visible range emission from blue to red, but the device exhibits short lifetime and low efficiency
Solution Approach 1:
The patent employs a composite emission layer structure combining a host material (formula 1 or 2 with specific aromatic ring structures) and a guest emission material (formula 3 with dopant compounds). This composite approach allows the host material to provide structural stability and charge transport pathways for extended device lifetime, while the guest material contributes to high emission efficiency through optimized energy transfer mechanisms. The specific structural features of the host (fused aromatic rings with defined substituents) create favorable conditions for both stability and efficient luminescence.
2Reliability
If conventional emission materials are used in organic EL devices, then the device can achieve visible range emission from blue to red, but the device requires high operating voltage
Solution Approach 1:
The patent modifies the molecular structure parameters of the emission layer materials by using specific fused aromatic ring systems (formulas 1 and 2) with controlled substituent patterns and conjugation lengths. These structural parameter changes result in optimized HOMO-LUMO energy levels and improved charge carrier mobility, which directly reduce the operating voltage required for device operation while maintaining long lifetime characteristics.
3Productivity
If phosphorescent compounds are used as emission materials to utilize triplet energy, then high luminous efficiency is achieved, but device complexity increases
Solution Approach 1:
The patent extracts and utilizes only the essential functional components needed for high efficiency emission by employing a simplified host-guest system where the host material (formulas 1 or 2) provides the structural framework and the guest material (formula 3) provides the emission function. This extraction approach eliminates the need for complex phosphorescent metal complexes while achieving high luminous efficiency through optimized fluorescent emission pathways, thereby reducing device 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 benzochrysene derivative results in an organic EL device with extended lifetime and high efficiency, capable of operating at lower voltages, improving the overall performance and longevity of the device.
Implementation Method 1
An organic electroluminescence device (hereinafter the term 'electroluminescence' is often abbreviated as 'EL') is a self-emission device utilizing the principle that a fluorescent compound which is an emitting material emits light by the recombination energy of holes injected from an anode and electrons injected from a cathode when an electric field is impressed.
Data Source
Figure 1
AI summary
A fused aromatic ring derivative shown by the following formula (1): wherein Ra and Rb are independently a hydrogen atom or a substituent; p is an integer of 1 to 13; q is an integer of 1 to 8; when p is two or more, plural Ras may be the same or different, and adjacent Ras may form a saturated or unsaturated ring; when q is two or more, plural Rbs may be the same or different, and adjacent Rbs may form a saturated or unsaturated ring; L1 is a single bond or a substituted or unsubstituted divalent linking group; and Ar1 is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms or a substituted or unsubstituted heteroaryl group having 5 to 50 ring carbon atoms.