Fluorine Ancillary Ligands for OLED Emission Control
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Solution Overview
Problem
Current organic light-emitting diodes (OLEDs), particularly blue phosphorescent and thermally activated delayed fluorescence (TADF) devices, face limitations in color saturation, efficiency roll-off, and device lifetime, which hinder their commercialization due to suboptimal ancillary ligands used in phosphorescent materials.
Innovation Solution
The introduction of fluorine-containing acetylacetone type ancillary ligands in metal complexes for OLEDs, which improve emission wavelength control and quantum efficiency, enhancing the performance of OLEDs by incorporating these ligands into the emissive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ancillary ligands are used in phosphorescent materials, then device structure is simple and manufacturing is easier, but emission wavelength control is poor and quantum efficiency is low
Solution Approach 1:
The patent applies parameter changes by systematically varying the fluorine substitution patterns (positions and numbers of F atoms) on the acetylacetone ligand structure. This allows precise tuning of the emission wavelength while maintaining the core ligand framework, thereby improving emission wavelength control without excessive complexity increase.
Solution Approach 2:
The patent employs composite materials by combining fluorinated acetylacetone ligands with metal centers (Ir, Pt, Os) to create metal complex phosphorescent materials. The fluorine-containing ligand structure forms a composite with the metal center, enabling improved quantum efficiency and emission wavelength control through the synergistic effect of the fluorinated organic ligand and the metal ion.
2Reliability
If conventional ancillary ligands are used, then device structure is simpler, but quantum efficiency and sublimation properties are insufficient
Solution Approach 1:
The patent utilizes parameter changes by modifying the fluorine substitution parameters on the acetylacetone ligand (number of F atoms, their positions at different carbon sites). This systematic parameter variation optimizes the quantum efficiency and sublimation properties while keeping the molecular structure complexity manageable through a standardized ligand platform.
Solution Approach 2:
The patent applies local quality by introducing fluorine atoms at specific local positions on the acetylacetone ligand structure rather than uniformly modifying the entire molecule. This localized fluorine substitution at specific carbon positions (C2, C3, C4, C5, C6) allows precise control over electronic properties and sublimation behavior without excessively complicating the overall molecular architecture.
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 ancillary ligands effectively tune emission colors, improve sublimation properties, and increase quantum efficiency, leading to more efficient, long-lasting OLEDs with improved luminance and reduced power consumption.
Implementation Method 1
An organic light-emitting diode (OLED) is a self-emitting solid state device... Once a bias is applied to the device, green light was emitted from the device.
Implementation Method 2
In 1997, Forrest and Thompson reported phosphorescent OLED, which uses triplet emission from heave metal containing complexes as the emitter.
Implementation Method 3
Recently, Adachi achieved high efficiency through thermally activated delayed fluorescence (TADF) of organic compounds. These emitters have small singlet-triplet gap that makes the transition from triplet back to singlet possible.
Implementation Method 4
Small molecule OLEDs are generally fabricated by vacuum thermal evaporation... The ligands can be used in emitters in the emissive layer of an organic electroluminescent device. By incorporating these ligands to metal complexes, the emission color can be more effectively tuned, and the sublimation properties and quantum efficiency are also improved.
Data Source
AI summary
Organic luminescent materials containing fluorine ancillary ligands are disclosed, which can be used as emitters in the emissive layer of an organic electroluminescent device. The organic luminescent materials is metal complexes which comprise a new series of fluorine containing acetylacetone type ancillary ligands. These novel ligands are effective in tuning the emission color, changing the sublimation properties, improving quantum efficiency and improving device performance. Also disclosed is an electroluminescent device and a formulation.