ALTernative to Indium Tin Oxide materials for sustainable growth of displays, solar and
automobile industries
The electronics/displays and photovoltaic (PV) sectors are intensively growing industries. Especially, the overall TCO market is valued at the moment more than $2 billion, where the Indium Tin Oxide (ITO) is an entrenched technology for displays manufacturing. Despite their many positive impacts, these industries face threats of: (i) sustainability of growth in terms of raw materials, energy and environment and (ii) competitive threat from Asia. Over the past 10 years, this enormous growth has led to an immense surge in demand for ITO which is the mainstream Transparent Conducting Oxide (TCO) global. The massive industrial growth rates and hence, high demand for ITO comes with substantial problems: high cost of ITO electrode production due to high demand and high price of indium and control of indium resources by China. To counter the above mentioned threats, the EU industry requires the replacement of ITO with lower cost and readily available metals.
Guiding principle of this project is to construct competitive high quality/low cost transparent oxides in order to replace ITO. Initially, computational models will be developed in order to predict phase diagrams of appropriate oxides, establish the stability rates of the various equilibrium phases, assist to resolve the doping mechanism of these materials especially as related to their crystal/defect chemistry, based on the theoretical frameworks. Afterwards, a “Green Dry Route” for the production of the alternative powders, which is environmental friendly, will be developed. The produced powders will be “super activated” in terms of reducing size to the nanometer level, using hyper-energy milling. Thus, compact PVD targets will be manufactured in order to be used for the sputtering of the TCO films.
The successful outcome of this project will have a significant impact in European competitiveness within the market of TCOs. Indeed, the impact is intended to be great, considering that the alternative TCOs address the need of constantly growing market sectors, which nowadays widely use ITO as TCO sputtering targets. These are the materials suppliers (TCO and other ceramic suppliers to the equipment sector) and more significantly the equipment manufacturers (electronics/displays, solar PV panels and automotive glass market). Both electronics/displays and solar PV panels markets are forecast to sustain their growth rates over the long term (10-12 years), while taking into account that all this markets are of strategic importance to EU.
Initially AltiTude project aims to develop computational model programmes based on theoretical frameworks. This will be achieved by predicting the appropriate stoichiometries of the suitable binary oxides from simulated phase diagrams. The use of first-principle calculations using density-functional theory (DFT) technique will contribute to predict effective electron masses of charge carriers and calculate the optical properties. The obtained results will enable the selection of the most appropriate m-TCO systems for further study which will be used in order to synthesize them. For the synthesis and production the selected m-TCO a special designed machine will be developed and applied. This synthetic approach is called atomisation and involves the manufacturing of powders by jetting a molten metal stream, the atomisation of streams by impacting it with a high energy perturbation following the direct oxidation of the metal particles will take place by letting them fall through an oxidation tunnel where they experience a high temperature in the presence of oxygen enriched air. Different combinations of metal oxides will be produced to yield m-TCO powders. The tree most promising m-TCO systems identified by the computational modelling will be synthesised and will be manufactured in large quantities. The next step will involve the fully characterisation of the m-TCO powders using physical and chemical methods. A very important task will be the activation method which will be developed in order to convert the selected micro m-TCO powders. The eventual purpose is to mill them into nano sized m-TCO powders in order to decrease their surface activity. Subsequently, the compacted discs or tiles of the m-TCOs will be sintered in a furnace. The activated m-TCO targets will be used to sputter thin films on glass substrates using a DC magnetron sputtering technique. The electrical, optical and chemical properties as well as the work function of the m-TCO will be exanimate by a variety of methods. The last step involves the construction of solar and touches screen panels by using the ITO alternative m-TCO substrates as top electrodes specifically to assemble a CIGS type device. All the m-TCO coating will be tested for their conductivity, light transmission, mechanical strength scratch resistance) and stability under accelerated aging.