Details of Grant 

EPSRC Reference:	EP/F015720/1
Title:	Preparation of Photovoltaic Silicon
Principal Investigator:	Fray, Professor D
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department:	Materials Science & Metallurgy
Organisation:	University of Cambridge
Scheme:	Standard Research
Starts:	01 October 2007	Ends:	30 September 2010	Value (£):	319,203
EPSRC Research Topic Classifications:	Electrochemical Science & Eng. Materials Characterisation
EPSRC Industrial Sector Classifications:	Manufacturing Energy
Related Grants:
Panel History:	Panel Date Panel Name Outcome 31 Jul 2007 Green & Sustainable Chemical Technologies Announced 23 Apr 2007 Green & Sustainable Chemical Technologies Sift Deferred
Summary on Grant Application Form
Silicon is the most common material used in solar cells and is, at present, a by-product of the semiconductor industry and it is also in short supply due to the increased demand for the material. Metallurgical silicon is first produced by the carbothermic of quartz at very high temperatures. Consuming 4kg of carbon and 14 kwh of electrical energy for each kg of silicon produced. It is then purified by forming trichlorosilane which is then reduced. This refining step generates 40 kg of carbon dioxide and needs about 130 kwh of electricity for every kg of purified silicon. This proposal addresses an alternative process in which the quartz is reduced to silicon by the process of electro-deoxidation in which the quartz is made the cathodes in a bath of calcium chloride. The anode will be an inert conducting oxide so that the products of process are silicon and oxygen, making this a green process with an energy consumption of 15 kwh/kg. As this unlikely to produce solar grade silicon in one step, the silicon is then electrorefined which will require about 10 kwh/kg of silicon produced. From the evidence in the literature, this should produce solar grade silicon. If this is found not to be the case, the quartz can be purified using hydrometallurgy and the final product zone refined. The innovative steps in this proposal are to combine together steps, already detailed in the literature but not used in combination, to produce solar grade silicon. As well as using well documented electrolytes, it is intended also to investigate ionic liquids, which melt below 100oC to make this a room temperature process. The overall goal is to investigate a process that consumes far less energy, avoids toxic chlorine containing gases and produces oxygen as a by-product.
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Organisation Website:	http://www.cam.ac.uk