Triazine Emitter Compounds for Cost-Effective TADF
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Solution Overview
Problem
Current emitter compounds for opto-electronic devices, particularly those emitting in the blue range, suffer from long excited state lifetimes and inefficient thermally activated delayed fluorescence (TADF), leading to unsatisfactory efficiency and roll-off, and often contain rare and toxic heavy atoms, limiting their cost-effectiveness and resource efficiency.
Innovation Solution
Development of emitter compounds based on a triazine core structure conjugated with phenyl residues and donor moieties, which exhibit high spin-orbit coupling constants, a small energy difference between excited singlet and triplet states, and high oscillator strength, enabling efficient TADF while being free from toxic and rare heavy atoms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If emitter compounds based on rare heavy atoms are used, then optical properties such as quantum yield and emission intensity are improved, but cost-effectiveness and resource efficiency deteriorate due to rarity and toxicity
Solution Approach 1:
The patent replaces expensive, rare heavy metal atoms with common, abundant elements (C, H, B, N, O, Si, P, S) to create emitter compounds that are both cost-effective and resource-efficient. This substitution maintains the desired optical properties while eliminating the cost and resource constraints associated with rare heavy metals.
Solution Approach 2:
The patent achieves high emission intensity without heavy atoms by optimizing molecular structure parameters: designing specific heteroaromatic core structures with carefully selected substituents that tune the HOMO-LUMO energy gap to produce visible light emission with high quantum yield and oscillator strength.
2Ease of manufacture
If conventional emitter compounds are used, then manufacturing simplicity is maintained, but optical efficiency deteriorates due to long excited state lifetimes and insufficient TADF
Solution Approach 1:
The patent optimizes key photophysical parameters by designing molecules with small S1-T1 energy gaps (enabling efficient TADF), appropriate HOMO-LUMO gaps (for visible emission), and high oscillator strengths. These parameter optimizations achieve high optical efficiency while maintaining manufacturing simplicity through straightforward synthesis routes.
Solution Approach 2:
The patent creates composite molecular structures combining heteroaromatic cores with specific donor and acceptor substituents. This composite approach enables simultaneous optimization of multiple properties: short excited state lifetimes, efficient TADF, high quantum yields, and visible range emission, all while maintaining ease of manufacture.
3Duration of action of moving object
If emitter compounds with long excited state lifetimes are used, then radiative decay probability is maintained, but TADF efficiency deteriorates due to insufficient reverse intersystem crossing
Solution Approach 1:
The patent precisely controls the S1-T1 energy gap parameter to be small (enabling efficient reverse intersystem crossing for TADF) while maintaining appropriate excited state lifetimes. This parameter optimization ensures that radiative decay and reverse intersystem crossing processes are both efficient, resolving the contradiction between lifetime and TADF efficiency.
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 proposed emitter compounds achieve high quantum yields and light efficiency in the visible spectrum, overcoming the limitations of existing materials by providing a cost-effective and resource-efficient solution with improved optical properties.
Implementation Method 1
organic emitter compounds with small ΔE(S1-T1) (energy differences between the first excited singlet state S1 and the first excited triplet state T1 of the emitter compound, preferably below 0.2 eV) are known. These emitter compounds typically emit light via a photo-physical mechanism called thermally activated delayed fluorescence (TADF)
Implementation Method 2
The emitter compound E shows comparably high spin-orbit coupling constants
Data Source
Figure 1~3
Figure 4
Figure 5A~5B
AI summary
The present invention relates to emitter compounds E of formula (I) or salts thereof based on a triazine core, substituted with at least one moiety of formula (Ia): and at least one donor moiety. Further, the present invention also refers to a light-emitting layer B comprising the emitter compound E and to an opto-electronic device OD comprising such light-emitting layer B. Moreover, the present invention relates to a method for generating light of a desired wavelength range by means of the opto-electronic device OD.