Soft Processing to Enable the Low Impact, Sustainable Manufacture of Inorganic Materials and Advanced Inorganic Semiconductor Composites

The development and large scale manufacture of advanced materials is one of the 'eight great technologies' that have been highlighted by the British Government that should be pursued to drive economic growth. The production of advanced composites with defined optical and electronic properties is a key area of research in this remit. The incorporation of semiconductor materials into host materials such as paper, plastics, polymers and textiles is of interest for the production of printed and wearable smart technology for personal energy generation or for health monitoring. However, despite research efforts in this area, many of the current pathways to produce advanced materials, for example semiconductors, require high temperature processing steps that limit the host matrix that can be used, or require high vacuum which limits scalability.

In this proposal we directly address this manufacturing limitation by using soft processing (i.e. low temperature <200 C, ambient pressure) to enable the potentially scalable production of a range of metal sulfide semiconductor polymer composites. We will show that our processing route is suitable for producing a range of binary, tertiary and quaternary metal sulfide polymer composities in a range of dimensionalities (i.e. 1D, 2D 3D), controlled by judicious choice of processing route. Finally, we will demonstrate how the manufacturing route we propose is compatible with laser printing, and will produce the world's first example of a Maxwell colour triangle for the Cu/Zn/Sn sulfide system.

Successful outcomes will be in the development of new soft processing pathways for a range of advanced semiconductor composites, which could lessen the economic and environmental impact of material manufacture for future generations. The manufacturing processes that we are proposing allow the design and realisation of a suite of new products with as yet unknown, but potentially advantageous, properties. Additionally, the advent of laser printing as a manufacturing route enabled by the research proposed here would provide a significant step change in the way that these materials can be processed and manufactured allowing high throughput printing of semiconductor arrays on inexpensive, light and flexible substrates such as paper or acetates for applications such as building integrated PV, personal energy generation or wearable sensors.

It is now increasingly recognised by policy and opinion formers and by the public that the engineering of advanced materials is one of the 'Eight Great Technologies' (https://www.gov.uk/government/publications/eight-great-technologies-infographics) which the UK government has decided to foster in partnership with industrial and academic researchers. Manufacturing techniques that lower the cost of production of these materials will increase sustainability and lower the impact of production.

Our proposal outlines universal soft processing (i.e. low temp <200 C, ambient pressure) techniques to produce a huge palette of metal chalcogenide semiconductors as well as routes to their incorporation into polymers of a range of dimensionalities (e.g. 1D , 2D, 3D) to produce a range of advanced functional polymer composite products with potential applications in solar power, thermoelectric energy generation or cooling, catalysis, energy storage, water splitting and spintronics. These will potentially have an impact in the way that UK plc will produce metal semiconductor composites, allowing them to meet the current need of present sectors e.g. photovoltaics, whilst allowing freedom to adapt the processing routes we propose for newer sectors not yet realised e.g. wearable thermoelectrics or spintronic devices. This will also provide societal impact as the technologies trickle-down to the consumer. Importantly the soft processes that we propose will provide energy savings to UK plc, improve sustainability and will not compromise the ability of future generations to meet their own manufacturing needs. We believe that our proposed technology is transformative in these respects, and after IP protection, supported by subsequent publications in high impact journals and talks at conferences we will attract significant industrial and corporate interest for licensing or spin out of our proposed manufacturing processes. The work is aligned with the 21st century products and sustainable industries research vision of EPSRC under the manufacturing the future call.

A successful outcome to our project would also establish laser printing as a manufacturing technology for high throughput direct printing of semiconductors onto light and flexible substrates e.g. paper, acetate, which is under digital control. We believe that this provides an exceptional transformative aspect to our proposal that will allow the massive throughput of printed semiconductor materials . It is likely to attract significant interest from UK plc after we have patented the processing route and it is our intention to pursue opportunities to licence the technology and the toners produced.

The proposal resides within the 'Manufacturing the Future' call, and as an investigator led project we have assembled a team of three experts in metal chalcogenide and polymer processing two of which also have successful track records in spin out of academic research. This makes it uniquely positioned to deliver the step changes proposed. The proposed research programme fits with underpinning applications in the grand challenge areas of Energy, Environment and Manufacturing. The programme is also fully aligned with the strategic energy research priorities of EPSRC.