Heteroleptic Copper(I) Complexes for Stable OLED Emitters
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Solution Overview
Problem
Current triplet emitters for OLEDs face challenges with long-term stability, thermal stability, chemical stability against water and oxygen, limited availability of important emission colors, reproducibility in manufacturing, high current density efficiency, high luminance levels, and the toxicity and complexity of emitter materials, as well as high costs.
Innovation Solution
Development of heteroleptic dinuclear copper(I) complexes with bridging ligands that enhance chemical, photophysical, and thermal stability through chelation effects, using bidentate or polydentate ligands to form stable complexes with improved chain length and flexibility, which also offer low toxicity and cost advantages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If triplet emitter materials are used to achieve high luminous efficacy, then light emission efficiency is improved, but long-term stability and thermal stability deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by using copper(I) complexes with specific ligand combinations (N-heterocyclic carbene and phosphine ligands) to achieve high luminous efficacy while improving stability. The specific parameter changes include using Cu(I) with L1-L6 ligands to create emitters that maintain high quantum yields while exhibiting enhanced thermal and chemical stability compared to traditional triplet emitters.
2Use of energy by moving object
If triplet emitter materials are used to achieve high luminous efficacy, then light emission efficiency is improved, but thermal stability deteriorates
Solution Approach 1:
The patent creates composite emitter materials by combining copper(I) centers with specific N-heterocyclic carbene ligands (L1-L6) and phosphine ligands. This composite approach allows the material to exhibit both high luminous efficacy through the Cu(I) triplet state and enhanced thermal stability through the robust coordination chemistry of the ligand system, with decomposition temperatures exceeding 200°C.
3Ease of manufacture
If traditional emitter materials are used, then manufacturing processes are established, but cost is high and toxicity is increased
Solution Approach 1:
The patent employs copper(I) as the central metal ion, which is significantly cheaper and less toxic than traditional triplet emitter metals such as iridium, platinum, or osmium. The Cu(I) complexes with L1-L6 ligands can be synthesized through straightforward coordination chemistry reactions, reducing both material cost and environmental toxicity while maintaining high emission efficiency.
4Illumination intensity
If emitter concentrations are increased to achieve high luminance, then brightness is improved, but quenching effects increase
Solution Approach 1:
The patent modifies the molecular parameters of the emitter by designing Cu(I) complexes with specific ligand structures (L1-L6) that create optimal steric and electronic environments. This allows the emitters to maintain high quantum yields and exhibit reduced concentration quenching, enabling operation at higher emitter concentrations to achieve high luminance levels without significant efficiency loss.
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 copper(I) complexes demonstrate increased thermal stability, high emission quantum yield, short emission decay times, and the ability to operate in high emitter concentrations without quenching, providing a wide range of achievable emission colors and efficient charge carrier transport.
Implementation Method 1
By using organometallic complexes with high emission quantum yields (transitions involving the lowest triplet states to the singlet ground states), a particularly high efficiency of the device can be achieved. These materials are often referred to as triplet emitters or phosphorescent emitters.
Implementation Method 2
The advantage of using bidentate or polydentate ligands is the increased chemical, photophysical and thermal stability, which is based on the chelating effect of the ligands.
Implementation Method 3
In a middle layer, the emitter layer, which also consists of an organic material, there are additional special emitter molecules at or near which the two charge carriers recombine and thereby lead to neutral but energetically excited states of the emitter molecules.
Data Source
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AI summary
The invention relates to copper(I) complexes of formula (A), wherein X* = Cl, Br, I, CN, OCN, SCN, alkynyl, or N3; N*∩E = a bivalent ligand independently of each other, wherein E = phosphanyl/arsenyl/antimonyl group of the form R2E (wherein R = alkyl, aryl, heteroaryl, alkoxyl, phenoxyl, or amide); N* = imine function, which is a component of an aromatic group that is selected from pyridyl, pyridazinyl, pyrimidyl, pyrazinyl, triazinyl, tetrazinyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, 1,2,4-oxadiazolyl, 1,2,4-thiadiazolyl, tetrazolyl, 1,2,3,4-oxatriazolyl, 1,2,3,4-thiatriazolyl, chinolyl, isochinolyl, chinoxalyl, and chinazolyl; "∩" = at least one carbon atom, which likewise is a component of the aromatic group, wherein the at least one carbon atom is located directly adjacent to both the imine nitrogen atom and the phosphorus, arsenic, or antimony atom; R2D-B-DR2 = a bidentate ligand, wherein D is selected independently of each other from the group comprising P, As, and Sb, wherein D is connected by means of a bridge B to a further group D, which is the same as or different from D, wherein the bridge B is one or more alkylene, alkenylene, alkynylene, or arylene groups or -O-, -NR-, or -SiR2- or a combination thereof, wherein the groups R are selected independently of each other from hydrogen, deuterium, halogen, or substituents that are bonded directly or by means of oxygen atoms (-OR), nitrogen atoms (-NR2), silicon atoms (-SiR3), or sulfur atoms (-SR), and alkyl, heteroalkyl, aryl, heteroaryl, alkenyl, or alkynyl groups or substituted alkyl, heteroalkyl, aryl, heteroaryl, and alkenyl groups.