Breakthrough in Thin-Film Solar Cells
New Insights Into the Indium/gallium PuzzleScientists at Johannes Gutenberg University Mainz (JGU) in Mainz have made a major breakthrough in their search for more efficient thin-film solar cells. Computer simulations designed to investigate the so-called indium/gallium puzzle have highlighted a new way of increasing the efficiency of CIGS thin-film solar cells. Researchers to date have achieved only about 20% efficiency with CIGS cells although efficiency levels of
30% are theoretically possible.
Thin-film solar cells are gaining an ever increasing proportion of the solar cell market. As they are only a few micrometers thick, they offer savings on material and manufacturing costs. Currently, the highest level of efficiency of about 20% is achieved by CIGS thin-film solar cells, which absorb the sunlight through a thin layer made of copper, indium, gallium, selenium, and sulphur. However, the levels of efficiency achieved to date are nowhere near the levels theoretically possible
The research team at Mainz University headed by Professor Dr Claudia Felser is using computer simulations to investigate the characteristics of CIGS, whose chemical formula is Cu(In,Ga)(Se,S)2. This research forms part of the comCIGS project funded by the Federal German Ministry for the Environment, Nature Conservation, and Nuclear Safety (BMU). IBM Mainz and Schott AG are collaborating with the Johannes Gutenberg University Mainz, the Helmholtz Center Berlin for Materials and Energy and Jena University in the project that is targeted at finding ways of optimizing CIGS solar cells. The researchers focused in particular on the indium/gallium puzzle that has been baffling scientists for years: Although it has been postulated on the basis of calculations that the optimal indium:gallium ratio should be 30:70, in practice, the maximum efficiency level has been achieved with the exactly inverse ratio of 70:30.
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http://www.sciencedaily.com/releases/2010/07/100719083044.htm