Iridium Complex Ligand Design for Near-Infrared Phosphorescence
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Solution Overview
Problem
Conventional light-emitting elements using fluorescent compounds have a theoretical internal quantum efficiency limit of 25% due to the statistical generation ratio of singlet to triplet excited states, restricting their emission efficiency, whereas phosphorescent compounds can achieve up to 75-100% efficiency but require materials that can efficiently convert triplet excited states to luminescence, which is challenging for ordinary organic compounds.
Innovation Solution
Development of an organometallic iridium complex with a dimethyl phenyl group and a quinoxaline skeleton, represented by specific general and structural formulas, which serves as a phosphorescent material capable of emitting near-infrared light with high quantum efficiency and long lifetime, integrated into light-emitting elements to enhance emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fluorescent compounds are used in light-emitting elements, then the structure is simple and ease of manufacture is improved, but the internal quantum efficiency is limited to 25% due to statistical generation ratio of singlet to triplet excited states
Solution Approach 1:
The patent changes the material parameter from fluorescent to phosphorescent compounds, specifically using iridium complexes with modified ligand structures. This parameter change enables exploitation of triplet excited states through phosphorescence, raising internal quantum efficiency from 25% to potentially 100% while maintaining manufacturability through systematic ligand design
Solution Approach 2:
The patent employs composite material design by combining iridium metal center with specifically designed organic ligands containing dimethyl phenyl groups and quinoxaline skeletons. This composite structure creates phosphorescent materials with enhanced stability and tunable emission properties, resolving the contradiction between performance improvement and manufacturing complexity
2Productivity
If phosphorescent compounds are used to achieve high emission efficiency, then the internal quantum efficiency can reach 75-100%, but the material requires efficient triplet excited state conversion which is difficult for ordinary organic compounds
Solution Approach 1:
The patent systematically modifies ligand parameters including the introduction of dimethyl phenyl groups at specific positions and quinoxaline skeleton variations. These parameter changes optimize the phosphorescent properties of iridium complexes, enabling efficient triplet state conversion while maintaining synthetic accessibility through well-established organic synthesis methods
Solution Approach 2:
The patent applies local quality modification by specifically functionalizing certain positions of the ligand structure with dimethyl phenyl groups while keeping other portions of the molecule relatively simple. This localized complexity enhancement achieves the desired phosphorescent performance without requiring complete structural redesign, thus maintaining ease of manufacture
3Reliability
If iridium complexes with modified ligands are synthesized to achieve high performance, then emission efficiency and lifetime are improved, but the synthesis process complexity increases
Solution Approach 1:
The patent segments the ligand design into modular components: a core structure with specific functional groups at defined positions, and interchangeable dimethyl phenyl group variations. This segmentation allows systematic optimization of emission properties through controlled modification of individual modules rather than complete redesign, managing synthesis complexity effectively
Solution Approach 2:
The patent employs preliminary action by pre-designing ligand structures with predetermined functional groups and connectivity patterns that are known to produce desired phosphorescent properties. This preliminary structural planning guides the synthesis process and reduces trial-and-error iterations, thereby improving emission efficiency while controlling synthesis 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 organometallic iridium complex enables light-emitting elements to achieve high emission efficiency and long lifetime by effectively converting triplet excited states to luminescence, overcoming the efficiency limitations of fluorescent compounds and producing near-infrared light with an emission wavelength around 700 nm.
Implementation Method 1
a compound capable of converting the triplet excited state into luminescence (hereinafter, referred to as a phosphorescent compound)
Implementation Method 2
Organic compounds are brought into an excited state by absorbing light
Data Source
AI summary
An organometallic iridium complex that has high emission efficiency and a long lifetime and emits deep red light (emission wavelength: around 700 nm) is provided. The organometallic iridium complex has a ligand that is represented by General Formula (G0) and has at least a dimethyl phenyl group and a quinoxaline skeleton.In the formula, R1 to R3 separately represent an alkyl group having 1 to 6 carbon atoms, a phenyl group, or a phenyl group having an alkyl group having 1 to 6 carbon atoms as a substituent.