TADF Polymer for Printable OLEDs via Energy Level Control
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Solution Overview
Problem
Existing TADF materials are not suitable for printing processes due to their low molecular weight and difficulties in adjusting solubility and viscosity, which hinders their application in large-area, low-cost manufacturing of organic light-emitting diodes (OLEDs).
Innovation Solution
A polymer with a repeating unit having a singlet and triplet energy level difference of less than or equal to 0.35 eV, incorporating electron donating and accepting groups, is developed. This polymer is used in a formulation with organic solvents and functional materials to create an organic electronic device, enhancing solubility and film-forming properties for improved printing compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low molecular weight TADF materials are used, then high luminous efficiency can be achieved, but poor solubility and viscosity control make printing difficult
Solution Approach 1:
The patent creates a composite material system by combining TADF emitters with polymer matrices or host materials. This composite approach allows the TADF material to maintain its high luminous efficiency while the polymer or host material provides the necessary solubility and processability for printing applications.
Solution Approach 2:
The patent modifies physical parameters such as molecular weight, solubility, and viscosity by incorporating TADF materials into polymer systems or using them as dopants in host materials. This parameter transformation enables the material to transition from a state suitable only for vacuum deposition to one suitable for solution-based printing processes.
2Ease of manufacture
If polymer materials are used to improve printing processability, then solubility and film-forming properties improve, but achieving TADF effect becomes more difficult
Solution Approach 1:
The patent applies local quality by incorporating TADF-emitting units at specific locations within the polymer structure or as localized dopant regions within a host matrix. This localized incorporation ensures that the TADF effect is maintained in specific functional regions while the overall polymer structure provides bulk processability and film-forming properties.
Solution Approach 2:
The patent carefully controls critical parameters including the concentration of TADF units, molecular weight of the polymer, and energy level matching between components. By optimizing these parameters, the system achieves both adequate solubility for printing and sufficient TADF emission efficiency.
3Loss of energy
If conventional TADF materials are used, then high luminous efficiency is achieved, but cost-effective large area manufacturing is hindered
Solution Approach 1:
The patent employs solution-based processing methods where TADF materials are dissolved in solvents to form printable inks or coatings. This liquid-state processing enables low-cost large-area manufacturing techniques such as spin coating, dip coating, or inkjet printing, replacing expensive vacuum deposition methods while maintaining high luminous efficiency through optimized material composition.
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 polymer exhibits high molecular weight and good solubility, facilitating better printing of OLEDs with improved luminous efficiency and processability, addressing the limitations of existing TADF materials.
Implementation Method 1
Adachi proposed the concept of reverse intersystem crossing so that an organic compound can be used, i.e. without using the metal complex, to achieve a high efficiency of phosphorescent OLED. This may come true by thermal activated delayed fluorescent material TADF.
Implementation Method 2
Reported existing TADF materials have a relatively low molecular weight and does not facilitates the printing process since it is not easy to adjust the solubility as well as the important parameters for the printing process, such as viscosity, surface tension.
Data Source
AI summary
Disclosed are a polymer, and a mixture or a formulation and an organic electronic device containing same, and applications thereof, and further a monomer of which the polymer is made; the polymer comprises on its side chain a repeating structure unit E, characterizing in that its S1(E)−T1(E))≤0.35 eV or even less, which may allow the said polymer having thermally activated delayed fluorescence (TADF) property. Thus a TADF polymer suitable for printing processes is provided, thereby reducing OLED manufacturing costs.