Organic Semiconductor Ink Composition for Stable Uniform Printing
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Solution Overview
Problem
Existing ink compositions for forming organic semiconductor layers in optoelectronic devices, such as OLEDs and solar cells, face challenges with chemical stability, phase separation, viscosity control, and uniformity, leading to non-uniform droplet sizes and degradation of opto-electrical properties during inkjet printing, which affects the reproducibility and longevity of these devices.
Innovation Solution
A printing ink composition comprising a p-type dopant with electron withdrawing groups and an aromatic nitrile compound as a solvent, which provides stability and uniformity, allowing for the formation of highly uniform organic semiconductor layers through inkjet printing, maintaining stability for extended periods and enabling scalable production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional solvents are used in ink compositions for inkjet printing, then the ink can be deposited onto the substrate, but the ink composition suffers from chemical instability, phase separation, and poor uniformity leading to non-uniform droplet sizes and degradation of opto-electrical properties
Solution Approach 1:
The patent changes the chemical parameter of the solvent by selecting aromatic nitrile compounds (benzonitrile, toluonitrile, cyanobenzene) with specific molecular structures and properties. These solvents provide optimal solubility for p-type dopants and charge transport materials while maintaining chemical stability and preventing phase separation during storage and printing processes, thereby achieving both chemical stability and droplet uniformity
Solution Approach 2:
The ink composition uses a composite solvent system comprising aromatic nitrile compounds combined with specific p-type dopants (such as Mo(tfd)3) and charge transport materials. This composite formulation ensures chemical stability, prevents phase separation, and maintains uniform droplet formation during inkjet printing while preserving opto-electrical properties
2Duration of action of stationary object
If the ink composition is stored for extended periods, then production scheduling is flexible, but the ink composition degrades leading to phase separation and loss of uniformity
Solution Approach 1:
The aromatic nitrile solvent creates a chemically inert environment that prevents degradation reactions of the p-type dopant and charge transport material during storage. The solvent's molecular structure resists oxidation and other chemical reactions, allowing the ink composition to maintain its stability and uniformity over extended storage periods without phase separation
Solution Approach 2:
The patent optimizes the solvent's physical and chemical parameters (boiling point, vapor pressure, solubility parameters) to ensure long-term stability. The selected aromatic nitrile compounds have parameters that prevent crystallization, phase separation, and chemical degradation during extended storage, enabling both long shelf life and composition stability
3Ease of manufacture
If conventional ink compositions are used, then the fabrication process is simple, but the opto-electrical properties degrade due to non-uniform layers and chemical instability
Solution Approach 1:
The aromatic nitrile solvent acts as an intermediary that facilitates uniform deposition of p-type dopants and charge transport materials during inkjet printing. The solvent's specific solubility characteristics ensure homogeneous distribution of active materials in the ink, leading to uniform film formation and reliable opto-electrical properties while maintaining fabrication simplicity
Solution Approach 2:
The patent optimizes key ink parameters including viscosity, surface tension, and solubility by selecting aromatic nitrile compounds. These parameter adjustments ensure proper inkjet droplet formation, uniform layer deposition, and chemical stability, achieving both ease of manufacture and reliable opto-electrical properties
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 ink composition ensures long-term stability and uniformity of organic semiconductor layers, enhancing the reproducibility and longevity of optoelectronic devices by maintaining the stability of p-type dopants and charge transport materials, facilitating scalable and cost-effective production.
Implementation Method 1
A printing ink composition comprising a p-type dopant with electron withdrawing groups and an aromatic nitrile compound as a solvent
Data Source
AI summary
The present invention is directed to an ink composition for forming an organic semiconductor layer, wherein the ink composition comprises: —at least one p-type dopant comprising electron withdrawing groups; —at least one first auxiliary compound, wherein the first auxiliary compound is an aromatic nitrile compound, wherein the aromatic nitrile compound has about ≥1 to about ≤3 nitrile groups and a melting point of about <100° C., wherein the first auxiliary compound is different from the p-type dopant; and wherein the electron withdrawing groups are fluorine, chlorine, bromine and/or nitrile.