Fluorinated Tetradentate Platinum Complexes for OLED Charge Balance
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Solution Overview
Problem
Current OLED devices face challenges with charge imbalance in light-emitting layers due to the use of heavy metal phosphorescent materials like iridium (III) complexes, which are costly and have low yield, leading to inefficient current efficiency and reduced service life.
Innovation Solution
Development of a fluorine-containing tetradentate cyclometalated platinum (II) complex as a phosphorescent acceptor material that improves charge distribution and balances hole and electron transmission, combined with a fluorescent doping material, enhancing energy transfer and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If iridium (III) complex phosphorescent materials are used in OLED light-emitting layers, then efficient triplet energy transfer and high luminescence efficiency can be achieved, but the preparation cost is extremely high and the service life is limited
Solution Approach 1:
The patent replaces expensive iridium (III) complexes with platinum (II) complex phosphorescent materials. Platinum is approximately ten times more abundant than iridium in the earth's crust, making platinum-based materials significantly cheaper while maintaining phosphorescent properties. The patent achieves this substitution by designing specific ligand structures (combining cyclometalating ligands with auxiliary ligands containing nitrogen and/or oxygen atoms) that stabilize the platinum (II) center and enable efficient phosphorescence, thereby reducing material cost without sacrificing device reliability
Solution Approach 2:
The patent modifies the chemical composition parameters of the phosphorescent acceptor material by transitioning from iridium (III) to platinum (II) complexes. This parameter change includes altering the metal center, oxidation state, and ligand coordination geometry. The specific ligand design (formula I or II) with tetradentate coordination creates a stable square planar platinum (II) complex that exhibits enhanced phosphorescence quantum yield and improved device stability, thus extending service life while reducing preparation cost
2Loss of energy
If mCBP or 2,6-MCPy are used as organic phosphorescent materials, then efficient triplet energy transfer can be achieved, but charge balance in the light-emitting layer deteriorates
Solution Approach 1:
The patent employs a composite phosphorescent acceptor material system consisting of platinum (II) complex coordinated with specific tetradentate ligands (formula I or II). This composite structure integrates the high triplet energy transfer capability of traditional phosphorescent materials with improved charge transport properties. The ligand design incorporates both electron-donating and electron-withdrawing groups, creating a balanced electronic structure that facilitates simultaneous hole and electron transport, thereby achieving both efficient energy transfer and charge balance
Solution Approach 2:
The patent introduces local structural modifications to the phosphorescent acceptor material by incorporating specific functional groups (pyridine, pyrimidine, triazole, tetrazole rings with fluorine substitution) at particular positions of the ligand framework. These local quality changes create regions with different electron densities and HOMO/LUMO energy levels, enabling optimized charge distribution. The fluorine atoms at specific positions enhance electron affinity and improve electron transport, while maintaining high triplet energy for efficient energy transfer from fluorescent dopants
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 fluorine-containing tetradentate cyclometalated platinum (II) complex improves current efficiency, service life, and reduces operating voltage in OLED devices, while offering better photochromatic purity when combined with boron-containing phosphorescent sensitized compounds.
Implementation Method 1
energy is transferred from the donor material to the acceptor material, so that the acceptor material is excited to emit light
Implementation Method 2
Commonly used organic phosphorescent acceptor materials are generally heavy metal atoms such as iridium (III), platinum (II), Pd(II)
Implementation Method 3
An Organic light-emitting diode (OLED) is a new generation of full-color display and lighting technologies
Data Source
Figure 1
AI summary
The disclosure belongs to the field of organic electroluminescence, and particularly relates to a fluorine-containing tetradentate cyclometalated platinum (II) complex, an electronic device and application thereof. The provided tetradentate cyclometalated platinum (II) complex has a structure shown in formula (I) or formula (II): in the formula (I) or formula (II), Fn indicates that there are one or more F substituted on a benzene ring where it is located, where n is a positive integer from 1 to 5. The compound according to the disclosure has good chemical stability, can improve and balance transport of holes and electrons, and makes energy transmission between donors and acceptors more efficient, which is specifically indicated by improvement of current efficiency and service life of an organic electroluminescent device with the compound or composition according to the disclosure, which has great application prospects in the field of OLED display and lighting.