Iridium Complex Host for OLED Luminous Efficiency
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Solution Overview
Problem
Existing organic light-emitting elements have low luminous efficiency and short lifetimes due to the use of zinc complexes and other metal complexes as hosts with phosphorescent light-emitting materials, which do not effectively trap carriers and transfer energy efficiently.
Innovation Solution
Incorporating an iridium complex represented by a specific general formula and a metal complex compound, such as beryllium, magnesium, or zinc-based compounds, into the emission layer to enhance luminous efficiency and lifetime by optimizing the combination of excitation energies, band gaps, and HOMO-LUMO levels, ensuring the host has a longer phosphorescence lifetime and smaller atomic number than the light-emitting material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If zinc complexes and other metal complexes are used as hosts with phosphorescent light-emitting materials, then the organic light-emitting element can be manufactured, but the luminous efficiency is low and the lifetime is short
Solution Approach 1:
The patent changes the key parameter of host material selection from conventional zinc complexes to iridium complexes with specific photophysical properties. By selecting hosts with longer phosphorescence lifetimes and smaller atomic numbers than the light-emitting materials, the patent optimizes energy transfer efficiency and carrier trapping, thereby simultaneously achieving high luminous efficiency and long lifetime while maintaining manufacturability
Solution Approach 2:
The patent employs composite material design by combining iridium complex hosts with phosphorescent light-emitting materials in specific weight ratios (host:guest = 95:5 to 99:1). This composite approach creates synergistic effects where the iridium complex host provides efficient energy transfer and carrier trapping, while the phosphorescent material provides light emission, resulting in superior device performance
2Device complexity
If conventional metal complexes are used as hosts, then the device structure can be simplified, but energy transfer is inefficient and carrier trapping is poor
Solution Approach 1:
The patent fundamentally changes the host material parameter from conventional metal complexes to iridium complexes with specifically optimized photophysical properties. The key parameter change is selecting hosts with phosphorescence lifetimes longer than the light-emitting materials and smaller atomic numbers, which enables efficient reverse energy transfer and effective carrier trapping, thereby achieving high energy transfer efficiency without increasing device complexity
Solution Approach 2:
The iridium complex host acts as an intermediary material that facilitates efficient energy and charge transfer between the electrodes and the phosphorescent light-emitting material. The host mediates the energy transfer process through its unique photophysical properties, enabling effective carrier trapping and reverse energy transfer to the guest material, thereby improving overall energy utilization efficiency
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 light-emitting element achieves high luminous efficiency and extended lifetime by using the iridium complex and metal complex combination, which improves energy transfer and carrier trapping, resulting in improved performance compared to previous phosphorescent light-emitting elements.
Implementation Method 1
An organometallic complex to be used as a phosphorescent light-emitting material is included in the compounds created heretofore. The organic light-emitting element emits light upon return of the exciton to its ground state.
Implementation Method 2
An organic light-emitting element (also referred to as 'organic electroluminescence element' or 'organic EL element') is an electronic element including a pair of electrodes and an organic compound layer placed between the pair of electrodes. An electron and a hole are injected from the pair of electrodes, and then the electron and the hole recombine in the organic compound layer to produce an exciton of a luminous organic compound.
Data Source
AI summary
Provided is an organic light-emitting element having high luminous efficiency and a long lifetime. The organic light-emitting element includes a pair of electrodes and an organic compound layer placed between the pair of electrodes, in which the organic compound layer includes an iridium complex having a benzo[f]isoquinoline of a specific structure as a ligand and a metal complex compound of a specific structure.