OLED Electron Injection Layer Composition for Lower Voltage and Longer Life
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Solution Overview
Problem
Existing organic electroluminescent devices face challenges in improving operating voltage, color-corrected efficiency, lifetime, voltage stability, thermal properties, crystallization tendency, and health and safety risks, particularly in mass production.
Innovation Solution
The device incorporates an electron injection layer (EIL) comprising compounds of formula (I) or (Ia) with specific anionic ligands and metal ions, and an electron transport layer (ETL) free of fluorine atoms, arranged between the anode and cathode layers, enhancing electron injection and transport properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electron transport layers with fluorine-containing compounds are used, then electron transport efficiency is maintained, but operating voltage is high and lifetime is limited
Solution Approach 1:
The patent changes the chemical composition parameters of the electron transport layer by using compounds with specific proton affinity ranges (10-15.6 eV) and controlling fluorine atom counts (2-6 fluorine atoms per molecule), which optimizes electron transport efficiency while reducing operating voltage and improving device lifetime
Solution Approach 2:
The patent employs composite material strategies by combining electron transport compounds with specific ancillary ligands (AL) and metal centers (M) in defined ratios, creating optimized composite formulations that achieve both low operating voltage and high reliability simultaneously
2Productivity
If electron transport compounds with high electron mobility are used, then color-corrected efficiency improves, but thermal stability deteriorates and crystallization tendency increases
Solution Approach 1:
The patent optimizes molecular parameters by selecting compounds with specific molecular weights (200-1000 g/mol), fluorine atom counts (2-6), and proton affinity ranges (10-15.6 eV), which balance electron mobility for high efficiency with thermal stability and reduced crystallization tendency
Solution Approach 2:
The patent introduces local structural features through specific ligand structures (L) with defined proton affinity characteristics and fluorine atom distributions, creating localized molecular properties that enhance electron transport while maintaining overall thermal stability
3Ease of manufacture
If conventional electron injection layers are used, then device assembly is simplified, but health and safety risks increase
Solution Approach 1:
The patent changes the chemical safety parameters by selecting electron injection compounds with specific proton affinity ranges and fluorine content, which maintain effective device assembly while reducing health and safety risks through inherently safer molecular structures
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 solution results in superior performance with lower operating voltage, improved color-corrected efficiency, extended lifetime, and reduced crystallization tendency, while minimizing health and safety risks, making it suitable for mass production.
Implementation Method 1
the EIL comprises at least one compound of formula (I) M n⊕[wherein M is a metal ion, L is an anionic ligand, wherein the proton affinity of L is selected in the range of ≥ 10 eV and ≤ 15.6 eV and wherein L comprises at least four fluorine atoms
Implementation Method 2
the EIL is in direct contact with the cathode layer... the ETL comprises a metal organic complex wherein the metal organic complex is free of fluorine atoms
Implementation Method 3
the ETL comprises a metal organic complex wherein the metal organic complex is free of fluorine atoms... the ETL is arranged between the first emission layer and the electron injection layer
Implementation Method 4
The holes and electrons recombine in the EML to generate excitons. When the excitons drop from an excited state to a ground state, light is emitted
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to an electroluminescent device comprising an electron injection layer comprising a compound of formula (I) and a metal and a display device comprising the organic electroluminescent device.