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Coalescence Dynamics of a Droplet Impacting on a Rectangular Pixel for Inkjet Printing
Jinhua Hong1, Yifan Jin1, Yiwei Jin2
1School of Advanced Manufacturing, Nanchang University, Nanchang330031, China.
Langmuir : the ACS Journal of Surfaces and Colloids
|December 8, 2022
Summary
Inkjet printing of organic light-emitting diodes (OLEDs) requires understanding droplet coalescence on pixels. Small droplet initial velocity and positioning errors improve OLED printing reliability.
Area of Science:
- Materials Science
- Fluid Dynamics
- Manufacturing Processes
Background:
- Inkjet printing of organic light-emitting diodes (OLEDs) faces challenges with liquid spreading beyond pixel boundaries.
- Droplet coalescence on rectangular pixels is critical for reliable OLED manufacturing.
Purpose of the Study:
- To analyze the dynamics of droplet coalescence on rectangular pixels in OLED inkjet printing.
- To investigate the impact of positioning errors and initial velocity on droplet behavior.
Main Methods:
- Development of a dynamics model based on mass and energy conservation.
- Derivation of dynamic equations to determine maximum spread length over time.
- Simulation of droplet coalescence using the Volume of Fluid method in FLUENT software.
Main Results:
- Analytical solutions from the dynamics model align with FLUENT simulation results.
- Droplet positioning errors and low initial velocity were found to enhance printing reliability.
- The coalescence process is conceptually divided into fusion and spread phases.
Conclusions:
- The study provides a validated model for understanding droplet coalescence in OLED inkjet printing.
- Optimizing droplet impact parameters, specifically reducing initial velocity and positioning error, is key to achieving reliable OLED manufacturing.
