Sustainable Manufacturing of Transparent Conducting Oxide (TCO) Inks and Thin Films

This project seeks to develop processes and resources towards sustainable and inexpensive high quality transparent conducting oxide (TCO) films (and printed tracks) on float glass, plastics and steel. In particular replacement materials for Indium Tin Oxide (ITO) and F-doped Tin Oxide (FTO). These materials are used in low-e window coatings (>£5B pa), computers, phones and PV devices. The current electronics market alone is worth in excess of £0.9 Trillion and every tablet PC uses ca 3g of tin. Indium is listed as a critical element- available in limited amounts often in unstable geopolitical areas. Tin metal has had the biggest rise in price of any metal consecutively in the last four years (valued at >£30K per ton) and indium is seen as one of the most difficult to source elements. In this project we will develop sustainable upscaled routes to TCO materials from precursors containing earth abundant elements (titanium, aluminium, zinc) with equivalent or better figures of merit to existing TCOs. Our method uses Aerosol assisted (AA) CVD to develop large scale coatings and developing new manufacturing approach to printed TCOs using highly uniform nanoparticle dispersions. AACVD has not been upscaled- although the related Atmospheric pressure (AP) CVD is widely used industrially. APCVD was developed in the UK (Pilkington now NSG) for commercial window coating methods- and in the UK glass industry supports >5000 jobs in the supply chain. Our challenge is to take our known chemistry and develop the underpinning science to demonstrate scale up routes to large area coatings. This will include pilot scale AACVD, nanoparticle dispersions and inks. Common precursor sets will be utilized in all the techniques. Our focus will be to ensure that the UK maintains a world-leading capability in the manufacturing of and with sustainable TCOs. This will be achieved by delivering two new scale up pathways one based on AACVD- for large area coatings and inks and dispersions for automotive and PC use. We will use known and sustainable metal containing precursors to deposit TCOs that do not involve rare elements (e.g. based on Ti, Zn, Al). Key issues will be (1) taking the existing aerosol assisted chemical vapour deposition (AACVD) process from small lab scale to a large pilot lab scale reactor (TRL3) and (2) developing a new approach to TCOs from transparent nanoparticle dispersions synthesized in a continuous hydrothermal flow systems (CHFS) reactor using an existing EPSRC funded pilot plant process (kg/h scale). Nano-dispersions will be formulated for use by the rest of the team, in jet and screen printing, advanced microwave processing and TCO application testing. Industry partners will provide engineering support, guidance on the aerosol transport issues, scale up and dynamic coating trials (Pilkington now NSG), jet and screen printing on glass (Xaar, Akzo Nobel, CPI) and use the TCO targets for Magnetron Sputtering of thin films on plastics (Teer Coatings). The two strands will be overseen by Life-cycle modelling and cost benefit analyses to take a holistic approach to the considerations of energy, materials consumption and waste and, in consultation with key stakeholders and policy makers, identify best approaches to making improvement or changes, e.g. accounting for environmental legislation in nanomaterials, waste disposal or recyclability of photovoltaics. We believe there is a real synergy of having two strands as they are linked by common scale up manufacturing issues and use similar process chemistries and precursors.