Organic Functional Material Formulation for Inkjet Printing
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Solution Overview
Problem
Existing formulations for organic semiconductor inkjet printing face challenges in achieving homogeneous deposition and uniform layer formation due to the complexity of solvent parameters such as surface tension, viscosity, and boiling point, which affect the performance and properties of the deposited layers.
Innovation Solution
A formulation comprising at least one organic functional material and two different organic solvents, where the first solvent has a boiling point between 250-350°C and viscosity greater than 15 mPas, and the second solvent has a boiling point between 200-350°C and viscosity less than or equal to 10 mPas, with the first solvent being selected from naphthalene derivatives and their hydrogenated forms, ensuring effective solubility and controlled deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single organic solvent is used in the formulation, then the formulation is simple, but homogeneous deposition and uniform layer formation cannot be achieved
Solution Approach 1:
The solvent system is segmented into two distinct components: a first organic solvent with high boiling point (250-350°C) and high viscosity (>15 mPas) providing structural stability, and a second organic solvent with lower boiling point (200-350°C) and lower viscosity (≤10 mPas) enabling homogeneous deposition. This segmentation allows each solvent to perform its specific function optimally.
Solution Approach 2:
The invention changes the physical parameters of the solvent system by selecting solvents with specific boiling point differences (at least 10°C) and viscosity ratios. The first solvent has viscosity >15 mPas while the second has viscosity ≤10 mPas, creating an optimal parameter combination for both deposition homogeneity and layer uniformity.
2Manufacturing precision
If solvents with different boiling points are used to control deposition, then deposition control is improved, but the choice of solvent becomes more challenging
Solution Approach 1:
The invention establishes specific parameter ranges for solvent selection: first solvent boiling point 250-350°C, second solvent boiling point 200-350°C, with a minimum difference of 10°C. These defined parameters simplify the selection process while maintaining precise deposition control.
Solution Approach 2:
The formulation uses a composite solvent system combining two organic solvents with complementary properties. The first solvent (high BP, high viscosity) provides stability and structural integrity, while the second solvent (lower BP, lower viscosity) ensures homogeneous deposition, creating a synergistic composite system.
3Manufacturing precision
If high viscosity solvent is used, then layer definition is improved, but inkjet printing capability is reduced
Solution Approach 1:
The viscosity function is segmented between two solvents: the first solvent provides high viscosity (>15 mPas) for layer definition, while the second solvent provides low viscosity (≤10 mPas) for inkjet printability. This segmentation allows the formulation to achieve both high layer definition and good inkjet printing capability.
Solution Approach 2:
The inkjet-friendly formulation uses a composite solvent system where the low-viscosity second solvent enables inkjet printing while the high-viscosity first solvent ensures proper layer definition during deposition and drying processes.
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 formulation enables uniform and well-defined organic layers with good layer properties and performance, facilitating efficient ink deposition and film formation in organic light-emitting devices.
Implementation Method 1
A formulation containing at least one organic functional material and at least two different organic solvents, a first organic solvent A and a second organic solvent B
Implementation Method 2
the vehicle being formulated to substantially completely evaporate while the film-forming material forms a solid film
Data Source
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AI summary
The present invention relates to a formulation containing at least one organic functional material and at least two different organic solvents, a first organic solvent A and a second organic solvent B, wherein the first organic solvent A has a boiling point in the range from 250 to 350°C and a viscosity of > 15 mPas, the second organic solvent B has a boiling point in the range from 200 to 350°C and a viscosity of ≤ 10mPas, the solubility of the at least one organic functional material in the second organic solvent B is ≥ 5 g/l, and the boiling point of the first organic solvent A is at least 10°C higher than the boiling point of the second organic solvent B; as well as to electroluminescent devices prepared by using these formulations.