Chemical Approaches to Low Temperature Indium Free TCOs and Other Metal Oxides
Simon Rushworth
EpiValence Ltd, The Wilton Centre, Redcar, Cleveland, UK, TS10 4RF
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The fabrication of metal oxide based thin TCO films at temperatures above 400C has been
demonstrated for a number of systems using many different types of metal precursor
chemistries and deposition techniques. The leading performance material is ITO but to date
it requires high processing temperatures or expensive vacuum sputtering techniques to attain
best performance. In addition ITO contains Indium which is on the Critical Raw Materials
register as unsustainable. To develop a solution using different material systems capable of
low temperature processing to enable continuous films or tracks on plastic, low thermal
resistant substrates using sustainable components remains a significant challenge. In the
H2020 INFINITY project [1] research is ongoing to develop new chemistries and processing
technologies to enable such metal oxide layers to be applied at the low temperatures required
for flexible polymer substrates.
In the INFINITY project EpiValence is working to assess different precursor materials that
offer the potential to reduce the processing temperatures required to give high quality TCOs.
In particular Si doped ZnO and Nb doped TiO2 were chosen as the material systems to study.
Initially simple metal alkoxides were functionalised to create a variety of species with
potential to yield the target metal oxide and these compounds were assessed by TGA for
decomposition temperature and degree of ZnO or TiO2 formation with a critical eye on the
thermal event profile. Having identified a suitable molecule further trials were performed to
establish its film forming capabilities.
In a separate project with Liverpool University more complex molecules and formulations are
being explored to enable TiO2 patterns to be created at lower temperatures.[2] Oxo clusters
that can template growth to produce high temperature phase (anatase) at low temperatures
(160C) are being studied with promising results. Addition of a dopant to create TCO is
underway.
In the presentation details of EpiValence capabilities and results from the INFINITY project
will be presented along with other proprietary work from the project with Liverpool
University on inkjet printing of TiO2 from new chemistries
Acknowledgements
The INFINITY project has received funding from the European Union’s Horizon 2020
research and innovation programme under grant agreement No 641927
References
[1]
[2] Titanium Oxo-alkoxide Clusters as a New Source Material for High Quality TiO2
Structures by Inkjet Printing (Printing for Fabrication 2016 (NIP32), Sept. 2016), Josh
Turner, Danielle Mehta, Helen C. Aspinall, Kate Black, and Simon Rushworth
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