Plasma-based synthesis of low-cost and environmentally friendly quantum dots with tailored energy band structure

Current photovoltaic (PV) technologies rely on physical principles that fundamentally limit the maximum solar cell efficiency, i.e. first and second generation technologies cannot produce efficiencies above ~31%. Both silicon-based and non-silicon devices are progressively approaching this limit with improved stability and device performance at reduced costs. It follows that significant improvement in device efficiency can be achieved only by deploying technologies that rely on new physical principles, so called third generation PV; this has been clearly highlighted in relevant UK and international PV roadmaps. In third generation solar cells quantum dots (QDs) often represent an important component and therefore methods to produce QDs that are low-cost, non-toxic and environmentally friendly are required. Currently the most efficient third generation solar cells use elements such as lead (Pb), cadmium (Cd), Selenium (Se) and tellurium (Te) which are either toxic or rare or expensive.
This research program deals with the synthesis and study of novel, low-cost, non-toxic and sustainable QDs from a combination of elements such as silicon, nitrogen, carbon and a range of low-cost, non-toxic and abundant metals. Furthermore the research will produce QDs with processes based on atmospheric pressure plasmas that are highly suitable to produce tailored properties and lead to material compositions not achievable with other methods. These proposed plasma processes can also be easily integrated in manufacturing lines for the production of full third generation solar cells.

The economic impact of the proposed research is achieved following three different pathways towards the energy sector, plasma technologies and skills development. Sales of in photovoltaic (PV) systems in the past decades have achieved a dramatic growth despite the limited degree of technological improvement. With recent increased R&D investments, this growth can be further improved with unprecedented economic impact. Nonetheless R&D must look for innovative ideas that can exploit new physical mechanisms capable of a drastic efficiency increase and especially a reduction of the associated costs. The proposed research programme is a clear step in this direction with a consequent global impact where the UK can play a considerable role. In fact, the success of this research project can lead to a solar cell technology that will be capable of attracting inward investment towards UK or to the creation of new companies. At the appropriate time, a business case will be made to warrant a successful transition from a research-based technology to an industrial reality. Technological plasmas are key enablers in a very wide range of fields that are making an indispensable contribution to the economy and that include the well-established microelectronics and semiconductor industry as well as emerging industries in health care, the energy and the environmental sectors. The development of reliable atmospheric-pressure plasma technologies in UK will represent an important achievement with the potential of considerable wealth creation and inward investment. The possibility of a new company in the field of atmospheric plasmas for nanofabrication and PV processes is well aligned with the expertise of the project team with several patents in cognate areas. The preparation of a workforce in important technological sectors will also contribute to an economic impact.
The global challenge in energy relies in technological progress to improve quality of life. Such challenge is both addressed by this proposal either directly or through its impacts and with the required channels to advance from science to societal benefits. The development of a viable PV technology as proposed in this project will bring great benefits to the global society through a sustainable and environmentally friendly energy harvesting approach. Furthermore, the team and relevant academic beneficiaries are in the position to initiate a program for the assessment of the toxicological impact of liquid-/air-born nanoparticles potentially assisting future policy making in drafting regulations for the health-risks of new and underdevelopment nanomaterials. This clearly shows the possibility of advancing policies almost in parallel with technological progress. Finally, the collaborative work with the project partners will greatly contribute to international development bringing additional societal impact.
The research activities planned within and following this EPSRC-funded project promote collaborations with overseas institutions contributing to the education of a globally engaged scientific and engineering workforce capable of performing in an international environment. The educational impact will originate also from the involvement of undergraduate and master students in all aspects of research. Current engagements with the engineering courses will provide opportunities to educate students in advanced subjects such as nanotechnology and solar cells so that future workforce generations can be adequately prepared. Exchanges of students/researchers with project partners are planned. In summary, the proposed research program includes fostering actions that produce a UK-based workforce in advanced technologies.