Organic Electroluminescent Host Material for Low-Voltage Durability
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Solution Overview
Problem
Existing organic electroluminescent elements face challenges in reducing driving voltage and improving durability.
Innovation Solution
The use of a compound with aryl or heteroaryl groups of two 6-membered rings connected through ring fusion, serving as a substituent, in the organic electroluminescent element's organic layer, particularly in the light emitting layer, enhances durability and reduces driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional host materials are used in organic electroluminescent elements, then the elements can operate, but the driving voltage is high and durability is insufficient
Solution Approach 1:
The patent modifies the molecular structure of the host material by changing chemical parameters - specifically using compounds with carbazole rings fused to naphthyridine or pyridine rings, and introducing specific substituents. This structural parameter change optimizes the HOMO/LUMO energy levels and charge transport properties, resulting in both reduced driving voltage and improved durability simultaneously
Solution Approach 2:
The patent employs composite molecular structures combining carbazole, naphthyridine, and pyridine units in specific configurations. The host material compounds integrate multiple functional moieties (electron transport, hole transport, and exciton management) within a single molecular framework, achieving superior performance in both voltage and durability
2Loss of energy
If phosphorescent light emitting materials are used to enhance efficiency, then luminous efficiency improves, but driving voltage reduction and durability improvements are still insufficient
Solution Approach 1:
The patent optimizes the energy level parameters of the host material by selecting compounds with specific HOMO and LUMO values that are well-matched to the phosphorescent emitter. This parameter optimization ensures efficient energy transfer while maintaining low driving voltage and high durability, resolving the contradiction between efficiency and durability
3Loss of energy
If phenyl groups are connected to undergo ring fusion to form carbazole rings, then luminous efficiency and low driving voltage are achieved, but durability remains insufficient
Solution Approach 1:
The patent creates composite molecular structures by fusing carbazole rings with naphthyridine or pyridine rings, and further introducing substituent groups. This multi-component composite structure combines the high efficiency of carbazole with the enhanced stability of naphthyridine/pyridine units, achieving both low driving voltage and improved durability simultaneously
Solution Approach 2:
The patent introduces specific substituent groups (such as fluoro, cyano, or other electron-withdrawing groups) at specific positions on the carbazole-naphthyridine-pyridine fused structure. These local modifications at specific sites optimize both the electronic properties for efficiency and the chemical stability for durability
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
This configuration results in an organic electroluminescent element with lower driving voltage and improved durability, enabling efficient light emission.
Implementation Method 1
The organic electroluminescent elements have organic layers between a pair of electrodes, and utilize, for light emitting, energy of an exciton generated as a result of recombination of electrons injected from a cathode and holes injected from an anode in the organic layer
Implementation Method 2
In recent years, by using phosphorescent light emitting materials, the efficiency of organic electroluminescent elements is being enhanced
Data Source
AI summary
An organic electroluminescent element including a substrate, a pair of electrodes including an anode and a cathode, disposed on the substrate, and at least one organic layer including a light emitting layer, disposed between the electrodes, in which at least one layer of the organic layer(s) contains a compound represented by the following formula, has low driving voltage and excellent durability.(X1 to X11 represent CR0 or N, and R0 represents a hydrogen atom or a substituent. Adjacent two of X1 to X11 each independently represent at least CR0, R0s of the adjacent two CR0s are bonded to each other to form a ring, and only one R0 of the adjacent two CR0s represents an aryl group or a heteroaryl group.)