Iridium Complex Phosphorescent Dopant for Organic EL Efficiency
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Solution Overview
Problem
Existing organic electroluminescence (EL) devices face challenges in achieving high current efficiency and long half-life, particularly in relation to driving voltage and power consumption.
Innovation Solution
An iridium complex is used as a phosphorescent dopant material in the light-emitting layer of organic EL devices, which is thermally stable and formulated to lower driving voltage and increase current efficiency or half-life, with specific formulations for red, yellow, and green light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phosphorescent organic EL device uses triplet excitons to improve internal quantum efficiency to 100%, then current efficiency is improved, but device complexity increases due to need for additional hole blocking layer or electron blocking layer
Solution Approach 1:
The patent extracts and eliminates the need for additional hole blocking layer or electron blocking layer by using a host material with built-in blocking capability. The host material itself possesses energy levels that naturally block charge carriers, removing the need for separate blocking layers while maintaining 100% internal quantum efficiency through triplet exciton utilization.
Solution Approach 2:
The host material serves multiple functions simultaneously: it acts as both the light-emitting host and the charge carrier blocking layer. The host material's energy levels are designed to provide both exciton formation capability and charge blocking functionality, consolidating what would traditionally require separate components into a single multi-functional material.
2Device complexity
If conventional organic EL materials are used to maintain simple device structure, then device complexity is low, but current efficiency and half-life remain insufficient
Solution Approach 1:
The patent changes the energy level parameters of the host material to achieve both simple device structure and high current efficiency. By selecting host materials with specific HOMO and LUMO energy levels that satisfy both the light emission requirements and the charge blocking requirements, the patent eliminates the need for additional layers while achieving 100% internal quantum efficiency and extended half-life.
3Productivity
If phosphorescent dopant material is used to achieve high internal quantum efficiency, then current efficiency is improved, but driving voltage increases
Solution Approach 1:
The patent applies local quality by creating distinct regions with different energy level characteristics within the device. The host material in the light-emitting layer has specific energy levels optimized for exciton formation and charge blocking, while the electron transporting layer has different energy levels optimized for electron injection and transport. This localized optimization allows high current efficiency in the emitting region while maintaining manageable driving voltage through the overall 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 iridium complex-based organic EL devices exhibit improved current efficiency and extended half-life, with driving voltage reduced to 3.7-4.7 V, and current efficiency increased to 18-47 cd/A, while half-life is extended to 410-770 hours depending on the light emission color.
Implementation Method 1
phosphorescent organic EL device make use of spin-orbit interactions to facilitate intersystem crossing between singlet and triplet states
Implementation Method 2
phosphorescent organic EL device make use of spin-orbit interactions to facilitate intersystem crossing between singlet and triplet states, thus obtaining emission from both singlet and triplet states
Implementation Method 3
The basic mechanism of organic EL involves the injection, transport, and recombination of carriers as well as exciton formation for emitting light
Implementation Method 4
the phosphorescent transition may be observed from an excited MLCT (metal to ligand charge transfer) state of organic metallic complexes
Data Source
AI summary
The present invention discloses an iridium complex represented by the following formula (1) and an organic electroluminescence device using the iridium complex as a phosphorescent dopant material. The phosphorescent dopant material may be for lowering a driving voltage or power consumption or increasing a current efficiency of half-life of the organic electroluminescence device.The same definition as described in the present invention.