Investigation of glyme additives to organometallic ink systems
Ben Fleming, Simon Rushworth
EpiValence Ltd, The Wilton Centre, Redcar, Cleveland, UK, TS10 4RF
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The printing of metal oxide based TCO films has been demonstrated for a number of systems
on hard temperature resistant substrates. However, to deposit continuous films or tracks on
plastic, low thermal resistant substrates remains a significant challenge. In the H2020
INFINITY project [1] research has been performed to develop new chemistries and
processing technologies to enable such metal oxide layers to be applied on flexible polymer
substrates using laser sintering to ensure low process temperatures.
To apply the initial coating new solution formulations have been investigated with a focus on
tailoring stability and reactivity to optimise performance. It has been found that simple metal
alkoxide solutions do not possess the correct properties for printing with rapid particulate
formation observed when exposed to air/moisture. To stabilise these solutions a range of
glymes have been investigated to establish which additive enhances properties the most. In
this paper we present the results from both thermogravimetric trials under controlled
conditions and vapourisation “drop tests” in open atmosphere to identify the impact of
different additives.
In more detail the TCO systems being investigated are doped Zinc Oxide (ZnO) and doped
Titanium Oxide (TiO
2
). Metal alkoxide moieties suited to forming these films at high
temperature have been modified to suit the new low temperature laser process through
functional alcohol additions with promising results. These molecules have been dissolved in
alcohol/hydrocarbon solvents to create Metalorganic inks. To further enhance the MO ink
performance in thin film application to a substrate in a uniform controlled manner different
additives based on glymes have been studied due to this family of compounds common usage
in inkjet inks and their highly useful properties [2]. Surprisingly different results were
observed when moving from monoglyme to diglyme to triglyme and tetraglyme. Drop tests
show that wettability and morphology of the as applied film can be significantly altered. TGA
data highlights that the additive removal can be achieved at modest temperatures for the
smaller molecules with diglyme providing the best compromise of stability, applicability and
removability.
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
References
[1]
[2] S Tang & H Zhao, RSC Adv. 2014; 4(22): 11251–11287
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