Investigation of the coffee ring effect in inkjet printed ITO patterns
Thiago Martins Amaral, Maria Gabriela Prada Rivero, Sabine Heusing, Peter König, Peter
William de Oliveira
INM-Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbruecken, Germany
e-mail
Key words:
transparent conducting oxides, ITO, inkjet printing, coffee ring effect
Printed electronics technology emerges as a new industrial alternative to reduce costs and
increase production speeds. In this context, advances concerning conductive inks are
decisive. The development of transparent conductive oxides (TCO) inks allows the possibility
to print many light-related electronic devices, such as solar cells.
In order to increase optical quality and obtain a smooth flat line of TCO, the coffee ring effect
should be avoided. Therefore, in this report, the composition of an ITO inkjet printable ink
was investigated by changing the solvents and proposing mixtures of solvents to control both
the drop evaporation and the Marangoni flows during evaporation. The inks were fabricated
by dispersion of In
2
O
3
:Sn (ITO) nanoparticles in a solvent with addition of a binder. The
morphology, the profile and the optical properties of the printed lines were investigated. It
was observed that, by employing a mixture of solvents, coffee ring effect free printed lines
could be obtained, which are promising for printed electronics. The coffee ring free lines
presented decreased haze and increased light transmission, compared to printed lines with
coffee ring effect.
Acknowledgements
This work was funded through the INFINITY project which has received funding from the
European Union’s Horizon 2020 research and innovation programme under grant agreement
No 641927
O 50
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