Organic Light Emission Layers Using Condensed Polycyclic TADF
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Solution Overview
Problem
Current light emitting devices for organic electroluminescence displays face challenges in achieving low driving voltage, high luminous efficiency, and long service life, particularly in efficiently utilizing phosphorescence emission and delayed fluorescence technologies.
Innovation Solution
A light emitting device is designed with a structure including a first and second electrode, and multiple organic layers, where at least one organic layer incorporates a condensed polycyclic compound represented by Formula 1, which is used as a luminescent material, and the electrodes are made from materials like Ag, Mg, Cu, Al, or their compounds, enhancing the device's efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional luminescent materials are used in organic electroluminescence displays, then the device can achieve basic light emission, but the luminous efficiency and service life are insufficient
Solution Approach 1:
The patent changes the chemical structure parameters of the luminescent material by introducing a specific condensed polycyclic compound with formula (1) containing nitrogen-containing six-membered aromatic rings. This structural parameter change enables the material to exhibit thermally activated delayed fluorescence with triplet energy level of 2.60 eV or more, simultaneously improving luminous efficiency and service life by optimizing the molecular structure for better charge transport and stability
Solution Approach 2:
The patent employs a composite material system where the condensed polycyclic compound is used in combination with a host material in the emission layer. The dopant (condensed polycyclic compound) is incorporated at specific concentrations (0.1-10 wt%) into the host matrix, creating a composite luminescent system that leverages the advantages of both materials to achieve high efficiency and long service life through synergistic effects
2Productivity
If phosphorescence emission or delayed fluorescence technology is implemented, then luminous efficiency can be improved, but the device complexity and material requirements increase
Solution Approach 1:
The patent extracts and utilizes the triplet state energy of the condensed polycyclic compound to generate singlet excitons through triplet-triplet annihilation. By taking out and harnessing the triplet exciton energy that would otherwise be lost, the device achieves delayed fluorescence emission with improved luminous efficiency while maintaining a relatively simple device structure without requiring additional complex components
Solution Approach 2:
The condensed polycyclic compound acts as an intermediary material that facilitates the conversion of triplet excitons to singlet excitons through thermal activation. This intermediary substance enables the delayed fluorescence mechanism by mediating the energy transfer process between triplet and singlet states, allowing efficient light emission without direct electrical excitation of the luminescent dopant
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 device achieves high efficiency in light emission with a low driving voltage and extended service life by utilizing the condensed polycyclic compound in the emission layer, specifically emitting thermally activated delayed fluorescence with a center wavelength of 420 nm to 470 nm.
Implementation Method 1
the emission layer may emit thermally activated delayed fluorescence
Data Source
AI summary
Provided is a light emitting device including: a first electrode; a second electrode facing the first electrode; and a plurality of organic layers between the first electrode and the second electrode, wherein at least one organic layer selected from among the plurality of organic layers includes a condensed polycyclic compound represented by Formula 1, and the first electrode and the second electrode each independently include at least one selected from among Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF/Ca, LiF/AI, Mo, Ti, In, Sn, Zn, Yb, W, a compound of two or more thereof, a mixture of two or more thereof, and an oxide thereof.