TADF Organic Emitters for OLEDs
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Solution Overview
Problem
Current organic electronic devices, particularly OLEDs, face challenges with high failure rates and inefficient production processes due to the use of rare and expensive metals like iridium and platinum, as well as poor processability of organic semiconductor materials, which hinders mass production and efficiency.
Innovation Solution
Formulations comprising thermally activated delayed fluorescence (TADF) compounds with a small singlet-triplet separation, processed from solution, allowing for the production of organic electronic devices with improved performance and reduced failure rates, eliminating the need for rare metals and enabling cost-effective mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If organometallic iridium and platinum complexes are used as phosphorescent emitters, then energy efficiency and power efficiency can be increased up to four-fold, but the cost increases due to rare and expensive metals
Solution Approach 1:
The patent replaces expensive organometallic complexes containing rare metals (iridium, platinum) with purely organic luminescent compounds that are cheaper and more abundant. These organic compounds achieve comparable energy efficiency through thermally activated delayed fluorescence (TADF) mechanisms, eliminating dependence on scarce metallic resources while maintaining high energy conversion efficiency.
Solution Approach 2:
The patent changes the fundamental emission mechanism from phosphorescence (requiring heavy metals) to thermally activated delayed fluorescence (TADF) in purely organic compounds. This parameter change involves designing molecules with specific HOMO-LUMO energy level configurations and small singlet-triplet energy gaps, enabling efficient light emission without rare metals.
2Use of energy by moving object
If organometallic phosphorescent emitters are used, then high efficiency can be achieved, but thermal stability decreases compared to purely organic compounds
Solution Approach 1:
The patent substitutes thermally sensitive organometallic complexes with thermally stable purely organic compounds. The organic TADF emitters exhibit superior thermal stability because they lack metal-ligand bonds that are susceptible to thermal degradation, while maintaining high emission efficiency through carefully designed molecular structures with appropriate energy level alignments.
Solution Approach 2:
The patent employs composite molecular designs combining electron-donating and electron-accepting moieties in TADF emitters. This creates charge-transfer states with small singlet-triplet energy gaps that enable efficient TADF while the purely organic composition provides inherent thermal stability absent in organometallic systems.
3Quantity of substance
If purely organic compounds are used as TADF emitters, then rare metals can be avoided and cost reduced, but processability from solution may be poor
Solution Approach 1:
The patent modifies the molecular parameters of TADF emitters by incorporating solubilizing groups and optimizing molecular weight and structure. These parameter changes enable the compounds to be dissolved in common organic solvents, allowing solution-based processing methods such as spin-coating, inkjet printing, and slot-die coating, thereby achieving both cost reduction and improved manufacturability.
Solution Approach 2:
The patent introduces solvent molecules as intermediaries that facilitate the processing of TADF organic compounds. By selecting appropriate solvents and optimizing solution formulation, the patent enables effective deposition of organic emitters from solution, bridging the gap between cost-effective organic materials and practical manufacturing processes.
4Reliability
If vacuum vapour deposition is used to apply organic semiconductor materials, then good opto-electronic properties can be achieved, but the production process becomes complex and expensive
Solution Approach 1:
The patent replaces the complex vacuum-based mechanical deposition system with simple solution-processing methods. Instead of requiring vacuum chambers, thermal evaporation equipment, and precise control of deposition conditions, the patent enables direct application of TADF emitter solutions onto substrates using conventional coating techniques, dramatically simplifying the production process while maintaining device performance.
Solution Approach 2:
The patent utilizes liquid-phase delivery (hydraulic approach) instead of vapor-phase deposition (pneumatic approach). By formulating TADF emitters as solutions that can be deposited and subsequently dried or cured, the patent eliminates the need for vacuum systems and complex deposition controls, enabling scalable and cost-effective manufacturing.
5Adaptability or versatility
If not all organic materials can be applied by vapour deposition, then certain materials cannot be used in electronic devices, but this limits material selection despite good opto-electronic properties
Solution Approach 1:
The patent develops a universal solution-processing platform that can accommodate a wide variety of organic TADF emitter materials with diverse structures and properties. This multi-functional approach allows virtually any organic compound with appropriate TADF characteristics to be processed from solution, greatly expanding material selection freedom beyond the limited subset compatible with vacuum deposition.
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 use of TADF compounds with a singlet-triplet separation of less than 0.15 eV in formulations with organic solvents results in organic electronic devices with enhanced performance and reduced production failures, facilitating inexpensive and reliable mass production of high-efficiency OLEDs.
Implementation Method 1
An alternative to the development of phosphorescent metal complexes is the use of emitters which exhibit thermally activated delayed fluorescence (TADF)
Implementation Method 2
The present invention relates to formulations comprising luminescent compounds having a small singlet-triplet separation, and to the use thereof for the production of organic electronic devices
Data Source
AI summary
The present invention relates to a formulation comprising organic materials for the production of organic electronic devices having a low failure rate.