Two-Coordinate Copper Carbene Complexes for OLED Emitters
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Solution Overview
Problem
Current OLED technologies face challenges with high production costs due to the use of rare noble metals, low external quantum efficiencies, and issues with concentration quenching, aggregation, and solubility of emitter materials, which limit their efficiency and stability in solid-state applications.
Innovation Solution
Development of two-coordinate copper, silver, and gold carbene complexes with a monoanionic ligand, exhibiting rotationally accessed spin-state inversion (RASI) photoemission, which are highly photoemissive, thermally stable, and soluble in organic solvents, enabling efficient solution processing and high quantum yields in OLEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If rare noble metals (iridium, platinum, gold) are used in OLED emitter materials, then high photoemission efficiency is achieved, but production costs increase significantly
Solution Approach 1:
The patent replaces expensive rare noble metals (iridium, platinum, gold) with abundant and inexpensive copper, silver, or gold(I) complexes as emitter materials in OLEDs. This substitution maintains photoemission functionality while dramatically reducing material costs, aligning with the principle of using cheap alternatives to replace expensive materials.
Solution Approach 2:
The patent changes the coordination geometry parameter from the conventional four-coordinate tetrahedral structure to a two-coordinate linear structure for copper and silver complexes. This parameter change fundamentally alters the electronic properties and photoemission characteristics of the complexes, enabling high efficiency emission while using abundant metals.
2Reliability
If emitter materials are used in solid-state OLEDs, then device stability is improved, but concentration quenching and aggregation occur reducing efficiency
Solution Approach 1:
The patent introduces bulky substituent groups (such as triisopropylsilyl groups) at specific positions on the ligand molecules. These local structural modifications create steric hindrance that prevents aggregation and concentration quenching of the emitter materials in the solid state, thereby maintaining high external quantum efficiency while ensuring device stability.
Solution Approach 2:
The patent designs emitter materials as composite structures combining the metal complex core with specially engineered ligand systems containing bulky substituents. This composite approach integrates the photoemissive functionality of the metal complex with the protective steric features of the ligands, achieving both high efficiency and solid-state stability.
3Stability of the object's composition
If conventional four-coordinate copper and silver complexes are used, then structural stability is achieved, but photoemission efficiency remains low
Solution Approach 1:
The patent fundamentally changes the coordination number parameter from four to two, transforming the geometry from tetrahedral to linear. This parameter change enables access to different electronic states and photoemission pathways that are not available in four-coordinate complexes, achieving high efficiency while maintaining stability through the linear geometry and appropriate ligand selection.
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
These complexes achieve external quantum efficiencies exceeding 15% and internal quantum efficiencies approaching 100%, with short excitation lifetimes, facilitating the production of bright and efficient OLEDs with reduced production costs and improved stability.
Implementation Method 1
organometallic complexes which exhibit rotationally accessed spin-state inversion (RASI) photoemission
Implementation Method 2
an emissive zone capable of emitting light when an electric current flows between the cathode and the anode
Data Source
Figure 1~2
Figure 3(a)~3(b)
Figure 4~5
AI summary
The present invention provides complexes of the formula(L)M(X),in which M is a metal atom selected from copper,silver and gold;L is a carbene ligand; and X is a monoanionic ligand. The complexes are useful as light emitters in the emissive zone of light-emitting devices such as OLEDs. The present invention also provides organometallic complexes which exhibit RASI photoemission, and the use of the same in light-emitting devices such as OLEDs.