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 controlled deposition and uniform layer formation due to the complexity of solvent parameters such as surface tension, viscosity, and boiling point, which affects the performance and properties of the deposited layers.
Innovation Solution
A formulation comprising at least one organic functional material and four different organic solvents, where the first solvent can engage in hydrogen bonding, the second solvent has a boiling point between 150 to 350°C, the third solvent between 100 to 300°C, and the fourth solvent between 200 to 400°C, with specific viscosity and solubility requirements, allowing for controlled deposition and improved layer uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single solvent or simple solvent mixture is used for inkjet printing of organic semiconductors, then the formulation is simple, but the deposition control and layer uniformity are poor
Solution Approach 1:
The solvent system is segmented into four distinct components, each with specific boiling point ranges and functional roles. This segmentation allows independent optimization of each solvent's contribution to deposition control, solubility, and drying characteristics, thereby achieving superior layer uniformity without excessive overall complexity
Solution Approach 2:
The invention employs a composite solvent formulation combining four different organic solvents with specific properties (boiling points, hydrogen bonding capabilities, solubilities). This composite approach creates a synergistic system where each component addresses specific requirements, achieving controlled deposition and uniform layers that cannot be obtained with single or simple mixture solvents
2Manufacturing precision
If solvents with extreme boiling points are used to control deposition, then deposition control improves, but the drying process becomes too long or energy-intensive
Solution Approach 1:
The drying process is segmented into stages corresponding to the evaporation of solvents in order of increasing boiling point. Lower boiling point solvents evaporate first during initial drying, while higher boiling point solvents remain to maintain layer integrity during subsequent processing, optimizing both deposition control and drying efficiency
Solution Approach 2:
The formulation utilizes solvents with boiling points spanning a wide range (100-400°C), allowing the drying process to be controlled by progressively removing solvents at different temperature stages. This parameter variation enables precise control over deposition while managing drying time and energy consumption through staged evaporation
3Stability of the object's composition
If solvents with high solubility are used to ensure complete dissolution, then material solubility improves, but the deposition control and layer definition become poor
Solution Approach 1:
The solvent system is segmented into components with varying solubility strengths. High solubility solvents ensure complete dissolution of the organic semiconductor material, while lower solubility solvents are present to reduce excessive material dissolution during deposition, thereby maintaining both material solubility and deposition control
Solution Approach 2:
The multi-component solvent system acts as an intermediary mechanism where different solvents modulate the overall solubility environment. The combination allows the formulation to maintain adequate solubility for complete dissolution while providing control over deposition through the presence of solvents with lower individual solubility contributions
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 effective ink deposition, resulting in uniform and well-defined organic layers with good layer properties and performance in electroluminescent devices.
Implementation Method 1
the first organic solvent A comprises a group, which is capable of receiving or giving a hydrogen bonding
Implementation Method 2
the second organic solvent B has a boiling point in the range from 150 to 350° C., the third organic solvent C has a boiling point in the range from 100 to 300° C., and the fourth organic solvent D has a boiling point in the range from 200 to 400° C.
Data Source
AI summary
The present invention relates to a formulation containing at least one organic functional material and at least four different organic solvents, a first organic solvent A, a second organic solvent B, a third organic solvent C, and a fourth organic solvent D, wherein the first organic solvent A comprises a group, which is capable of receiving or giving a hydrogen bonding, the second organic solvent B has a boiling point in the range from 50 to 350° C., the third organic solvent C has a boiling point in the range from 100 to 300° C., and the fourth organic solvent D has a boiling point in the range from 200 to 400° C., is present in an amount from 0.01 to 1 vol.-% and has a viscosity of ≥15 mPas, the solubility of the at least one organic functional material in the second organic solvent B and in the fourth organic solvent D is ≥5 g/l, the boiling point of the third organic solvent C is at least 10° C. lower than the boiling point of the second organic solvent B; and the boiling point of the fourth organic solvent D 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.