Low-Particle Organic Semiconductor Ink Formulation for Printing
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Solution Overview
Problem
Existing methods for fabricating organic electronic or optoelectronic devices face challenges in achieving homogeneous deposition and reducing defects, particularly due to the presence of particles in the submicrometer range, which affect the layer structure and quality of the devices.
Innovation Solution
A formulation comprising organic semiconducting materials with a molecular weight of at least 10,000 g/mol and organic solvents with a boiling point of ≥ 90°C, having a viscosity between 1.5 to 100 mPas, and containing less than 10,000 particles per liter with an average size of 0.1 to 20 µm, is developed for use in coating or inkjet printing, allowing for the preparation of electronic or optoelectronic devices with reduced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If particles are present in the ink formulation, then the ink can be prepared with standard filtration methods, but particle accumulation causes clogging of ink channels and non-uniform ink application
Solution Approach 1:
The patent changes the physical-chemical parameters of the ink formulation by selecting specific solvent combinations with controlled boiling points and vapor pressures. This parameter optimization ensures that the ink maintains appropriate viscosity and flow characteristics while minimizing particle formation and accumulation, thereby preventing clogging without requiring complex filtration systems.
Solution Approach 2:
The patent applies preliminary action by carefully selecting and pre-mixing solvents with specific properties before ink formulation. The solvents are chosen to inherently prevent particle aggregation and ensure uniform dissolution of organic semiconducting materials, addressing potential clogging issues before they occur during the printing process.
2Reliability
If particles are reduced in the ink formulation, then ink flowability improves and clogging is prevented, but achieving uniform deposition becomes more challenging
Solution Approach 1:
The patent employs composite material principles by formulating the ink with a specific combination of organic solvents and polymeric organic semiconducting materials. This composite formulation ensures that the ink maintains optimal rheological properties for uniform flow and deposition, achieving both reliable ink channel flow and precise layer formation simultaneously.
Solution Approach 2:
The patent optimizes deposition uniformity by carefully controlling parameters such as solvent boiling point, vapor pressure, and ink viscosity. These parameter adjustments ensure that the ink flows uniformly through the printing head while maintaining consistent deposition characteristics on the substrate, achieving both reliability and manufacturing precision.
3Productivity
If solvents with low boiling points are used, then ink evaporation is faster and drying time is reduced, but particle formation increases and layer quality deteriorates
Solution Approach 1:
The patent changes the boiling point parameter of the solvent system to an optimal range (≥90°C) that balances evaporation rate with particle formation control. This parameter optimization ensures sufficiently fast drying for productivity while preventing excessive particle formation that would deteriorate layer quality, achieving both goals simultaneously.
Solution Approach 2:
The patent applies preliminary action by pre-selecting solvents with appropriate boiling points and vapor pressures before the drying process. This preliminary selection ensures that the solvent system provides controlled evaporation rates that prevent particle formation during drying, maintaining layer quality while achieving acceptable drying speeds.
4Manufacturing precision
If ink viscosity is increased, then particle suspension is improved and uniformity is enhanced, but flowability decreases and clogging risk increases
Solution Approach 1:
The patent optimizes the viscosity parameter of the ink formulation to a specific range that balances particle suspension capability with flowability. This viscosity optimization ensures sufficient particle distribution uniformity while maintaining adequate flow characteristics to prevent clogging, achieving both manufacturing precision and ease of operation.
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 the production of electronic or optoelectronic devices with improved uniformity and reduced defects, enhancing the quality and performance of layers in devices such as OLEDs, OTFTs, and solar cells by ensuring good flowability and preventing clogging in printing heads.
Implementation Method 1
a formulation comprising one or more polymeric organic semiconducting materials and one or more organic solvents
Implementation Method 2
The formulation of the present invention is filtered
Implementation Method 3
The layer, comprising the one or more organic semiconducting materials, is deposited onto a substrate, followed by removal of the solvent
Data Source
AI summary
The present invention relates to formulations comprising at least one organic semiconductor and at least one organic solvent, characterized in that the formulation contains less than 10,000 particles per liter formulation having an average size in the range from 0.1 to 20 pm, to their use for the preparation of electronic devices, to methods for preparing electronic devices using the formulations of the present invention, and to electronic devices prepared from such methods and formulations.