Ink Composition Ohnesorge Number Optimization for Jetting
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Solution Overview
Problem
Conventional ink compositions for light-emitting devices face challenges in jetting performance due to inappropriate Ohnesorge numbers, leading to issues such as jetting failure, despite considerations of weight percent, solvent boiling point, surface tension, and viscosity.
Innovation Solution
An ink composition with an Ohnesorge number of 0.1 to 0.2, comprising a solvent and an electron transporting material represented by Formula 1, is developed, which includes specific solvents like cyclohexylbenzene and electron transporting materials like diphenyl phosphine oxide, ensuring proper jetting characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ink compositions are used with traditional solvent and material combinations, then the formulation flexibility is maintained, but jetting performance deteriorates due to inappropriate Ohnesorge numbers
Solution Approach 1:
The patent applies parameter changes by optimizing the Ohnesorge number to a specific range (0.1 to 0.2) through adjustments in solvent selection, electron transporting material structure (Formula 1), and their proportions. This parameter optimization resolves the contradiction by achieving reliable jetting performance while maintaining formulation flexibility through systematic control of key parameters rather than imposing rigid constraints.
2Reliability
If the Ohnesorge number is not optimized, then the ink composition can be formulated with various materials, but jetting reliability deteriorates leading to jetting failure
Solution Approach 1:
The patent implements parameter changes by establishing the optimal Ohnesorge number range (0.1 to 0.2) as a critical control parameter. This resolves the contradiction by providing a clear manufacturing precision target (the Ohnesorge number range) that directly improves jetting reliability, transforming the vague requirement of 'proper jetting characteristics' into a quantifiable control parameter.
Solution Approach 2:
The patent employs feedback by using the Ohnesorge number as a diagnostic metric to evaluate and adjust ink composition formulations. By calculating and controlling the Ohnesorge number based on viscosity, surface tension, and nozzle diameter parameters, the formulation process receives feedback that guides material selection and proportioning to achieve reliable jetting performance.
3Reliability
If various materials are considered for ink composition, then formulation versatility is maintained, but jetting performance deteriorates due to lack of optimization
Solution Approach 1:
The patent resolves this contradiction by introducing the Ohnesorge number as a governing parameter that unifies material selection criteria. Instead of evaluating materials based on multiple independent properties, the formulation process focuses on achieving the target Ohnesorge number range (0.1 to 0.2), which inherently balances viscosity, surface tension, and other critical properties. This parameter-based approach maintains material versatility while ensuring jetting reliability.
Solution Approach 2:
The patent applies composite materials by combining solvents and electron transporting materials (Formula 1) in specific ratios to achieve the target Ohnesorge number. This composite approach allows flexibility in selecting individual materials while ensuring the overall composition meets the jetting performance requirements through the synergistic effect of the combined components.
Data Source
AI summary
An ink composition includes: a solvent; and an electron transporting material substantially dispersed in the solvent and of Formula 1, wherein the ink composition has an Ohnesorge number of about 0.1 to about 0.2:[Ar1]b1-[(L1)a1-R1]c1 Formula 1wherein the variables are defined herein.